Exterior Masonry Paint – Which is Best?

Painting exterior masonry is a fairly simple process of adequate preparation and selection of paint colour. The choice of paint is usually a matter of budget and/or personal bias because exterior masonry paints are all the same right?

Not really no.

There are water based paints, oil based masonry paints and mineral paints as well as a rubber based paint known as Pliolite. Factor in also the new ‘Eco Paints’ and you’d be right to be a little confused.

So which is best and does it really matter?

First of all the choice of paint will depend upon the type of wall surface and whether it has been painted before. Generally, the exterior walls of your property will be plain brick or stone or finished with some kind of cement based render – older properties (particularly those with a single thickness of wall) may have a lime based render finish.

Previously Painted Walls

For previously painted walls in good condition a standard water based masonry paint such as Dulux Weathershield should be perfectly adequate. If your budget doesn’t stretch that far then an own brand equivalent should be fine.

Most exterior wall paints are water based and contain some form of acrylic binder. They should be micro-porous – in other words, they allow any moisture trapped in the wall surface to evaporate.

Alternatives include solvent-based paints for all-year round application and Pliolite rubber based paints for inclement environments.

Unpainted Cement Rendered Walls

If you have  cavity walls and the render is in good, dry condition there is no reason why you shouldn’t use a conventional water based finish. You may need to do a little preparation such as filling any minor cracks and priming any loose or friable areas with stabilising solution.

Afterwards simply coat with two or three coats of masonry paint in your chosen colour (the first coat slightly thinned with water).

Stabilising Primer is ideal for chalky or powdery areas. It acts like an adhesive – providing a solid base for subsequent coats of paint to stick to.

However, it is NOT a suitable primer for ordinary rendered walls despite what your neighbour or bloke down the pub may tell you. A thinned coat of regular masonry paint is all that is needed as a primer for sound rendered walls and stonework.

For older properties with a single thickness of wall it will be necessary to ensure that the wall is able to breathe (in other words, the surface should be permeable and allow any trapped moisture to escape). Ideally the render will be lime based or with a low cement content finish.

Dulux Weathershield Masonry Paint
In many cases, a quality water based system, such as Dulux Weathershield will perform quite adequately and should last many years.

However, you may consider using a mineral based paint which could perform considerably better?

Mineral Based Exterior Paints

Put simply,  mineral paints are made with a silicate binder which reacts with the surface of the wall to form a long-lasting bond, unlike traditional paints which simply form a skin. They are naturally alkaline, so inhibit mould growth and carbonation; mineral paints also have the added advantage of being eco-friendly too.

The disadvantage is that they require more thorough preparation, special primers and are, initially, much more expensive – although the increased performance should pay back over the long term.

Beek Mineral Paints

There are a few specialist manufacturers of mineral based paints – the main two being Keim and Beeck

Each have their own detailed specifications for different kinds of wall surface and these must be followed to the letter in order to enjoy the maximum performance.

Lime Rendered Walls

For old buildings with a lime based render or lime based pointing a traditional Limewash is ideal. Limewash is simply a paint made from lime powder and water together with a colourant.

The main advantages of limewash are they bind to the surface very well and are totally breathable – another benefit is that they are relatively inexpensive.

Care needs to be taken with application and sometimes additional binders need to be added to aid adhesion.The finished result can be very striking though – looking much more natural than a traditional paint finish.

Limewash paints are available from a number of sources including Ecos, Ty-Mawr, Little Greene and  Farrow & Ball.

ECO Paints

Technically, an ECO paint is simply a paint which has a very low or zero volume of Volatile Organic Compounds. While some ECO paints are obviously superior to others there isn’t any case for suggesting that an ECO paint will perform any better or worse than any other form of exterior paint – it will simply be a matter of personal choice.

It’s worth noting, however, that mineral and lime based finishes, mentioned above, are by their very nature eco-friendly – so would make a good choice if you wanted to be as environmentally friendly as possible?

A Little Preparation Will Go a Long Way

As always, the amount of time you spend preparing the surface will show in the end result and, if done properly, a painted exterior wall will last at least ten years before it needs re-coating.

Bear this in mind when making your choice of materials as it really isn’t worth skimping and a few extra pounds spent at the outset will go a long way.

Q&A Masonry Paints Advice

Painted walls near the coast, spots of paint have come out in what I can only call water blisters causing the paint to come off, and then a mould….? READ MORE…

I purchased a house that was plastered and never painted for 12 years, I was advised to use a stabilizer before painting.

I then used Pliolite paint as I thought living near the coast would be longer lasting, Several spots of paint have come out in what I can only call water blisters causing the paint to come off, and then a mould is on the spot where the paint was , Is there a cure for this? John

There isn’t a cure, as such, since you would need to take yourself back to before you started. Trapped moisture is forcing its way out hence the blistering and subsequent mould patches.

The best way forward is to scrape off any loose paint and allow plenty of time for any embedded moisture to work its way out – this may take a long time and I would certainly not attempt any repainting until late Summer. The mould should clear itself up once the source of moisture has gone but you can treat any large, persistent areas with a fungicidal wash

Patch paint with a regular water-based masonry paint (maybe thinned a little first coat to act as a primer), as you go. This may end up being a process you have to keep repeating or you may be fortunate and have seen the worst of it already.

In a domestic setting there is no sensible use case for Pliolite paints and stabilising solutions should only be used where the surface is loose/powdery, and never as an overall primer.

Neighbour’s new extension is obstruct access to side of our house, what’s the best way to protect it…? READ MORE…

Our new neighbour is building a double storey wrap round extension to their house & this leaves only a 100mm gap between his & our main side walls. His garage was attached to our north facing main side wall & once demolished, we had to bear the expense of having it rendered properly.

Once he has built his extension, we will never ever be able to access our side wall due to both houses being only 100mm part & they run about 15m deep.

In view of this & to offer the very best possible protection for the longest possible time to our main side wall, which type of external Masonry paint should we use – a water based one like Dulux Weathershield, Wethertex AP77 or a rubberised Pliolite type one?

Which is the best & longest lasting water based & Pliolite paints to get for our situation please? Bhav

The answer is to use a standard water-based masonry paint to protect the wall surface from the weather, this is what it is designed to do.

There are mineral-based finishes that create a ‘chemical bond’ which can outperform regular masonry paint but they are expensive, require professional application and wouldn’t really be worth it in this situation.

So called ‘specialist paints’ such as Wethertex make great claims about flexibility but it is a film of paint at the end of the day and is not able to withstand the kind of forces that cause cracks in walls – which is how water will penetrate a building, not, as they imply, through some state of osmosis that only other brands of paint are susceptible to.

Pliolite paints are formulated to dry quickly so you can use them when rainfall is imminent – which isn’t much of a solution to your problem I am afraid. They offer no advanced protection and will perform worse than standard paints over time for the simple reason that they offer a compromise which is only advantageous for commercial applications (ie, you can the job done in less than perfect weather conditions).

One a positive note, your neighbours extension is going to offer a significant degree of shelter to this wall which would be otherwise fully exposed. So may actually be of some benefit?

Please can you recommend a dirt and moss resistant masonry paint. READ MORE…

There are a few specialist manufacturers of exterior paint that claim to me mould and dirt resistant but a lot depends on the type of surface, its current condition and location as to whether these paints have any chance of working as intended.

The current favourite within the trade is Zinsser Perma-White (Exterior)

See also : https://decorator.uk/fungicidal-paints-do-they-work-which-is-best

Seafront Victorian Terrace – Is there a better paint to withstand the elements? READ MORE…

Hi this is a great site very useful. My house is an old Victorian terrace (1888) on the seafront. It is rendered and painted regularly with Sandtex STHC smooth. Long shot I know but is there a better product to withstand the elements and do you have any advice on any specialist gloss paint for the window woodwork.

As you might expect the repainting seems to be every 5 years rather than 10. Just wondered if there was a better product or whether more coats would be a good idea. Tom

Dulux Trade Maximum Exposure Masonry Paint is formulated for coastal environments and is claimed to perform better than the regular alternative. Whether it would be worth the added expense is hard to say though since you’ll be painting over an existing coating and, as always, any paint is only as good as the surface it is applied to.

In theory, you may get a bit more time between recoats but it can’t be guaranteed so that’s a risk you’ll have to judge for yourself.

As for the woodwork, Dulux Trade Weathershield exterior undercoat and gloss will perform as well as anything and much better than most standard finishes. In your case, over existing woodwork that is in good condition, the oil-based option will be the better choice.

Re applying extra coats, with previously-painted woodwork, absolutely yes. Two coats of gloss are better than one and three coats better than two.

And for masonry paint, not so much, since you want any internal moisture to be able to escape and multiple coats will have a detrimental effect on this process.

Is there an exterior paint for common brick? READ MORE…

I have an old terraced property built around 1910. I would like to paint the brick wall in my back yard. The previous owner painted it – probably many, many years ago. The existing white paint is still on much of the wall, although much of it is now flaking off. I was planning to scrape off the loose, flaking paint, clean it and then paint it with Dulux Trade Weathershield Exterior Masonry Paint in brilliant white.

However, the on-line data sheet says the paint is not suitable for ‘common brick’. Do you think my 1910 old yard wall is likely to be common brick?

I don’t really know what that is.

If so, is there a paint for common brick? I thought this would be a fairly straightforward task to spruce up the yard, especially as it had previously been painted, but now I’m worried I am doing this wrong. Dave

Common Brick is term used to describe high-density bricks which are typically used at DPC level because they are resistant to the absorption of moisture. It is not usual for commons to be used for yard walls or large areas of brickwork elsewhere.

It is unfortunate that the word ‘common’ is used out of context in this case since these kind of bricks are anything but.

Undiluted primer applied to Sto Render. READ MORE…

We have a sto render on part of our house which has become discoloured. My decorator inadvertently applied sto prime micro primer undiluted – it should be 1:10. Apart from being expensive will this have any knock on effects on the render or apply the paint – another sto product – on top? Thanks, Ruth

It shouldn’t effect any subsequent coats but what may have happened is the primer has formed a film on top of the render instead of soaking in. As a consequence you may suffer from a premature lack of adhesion, especially if any moisture starts to build up at the back of this film.

Signs of problems will be if flakes of paint start becoming apparent, after maybe 12 months time?

Of course, it is equally possible you have no problems at all; it all depends on the absorbency of the wall, ambient atmospheric conditions, etc.

Without a doubt though, your decorator is liable for putting the works right if any problems do occur. He may have insurance that covers this possibility although his premiums will escalate considerably if you have to make a claim – not your problem though.

Can I paint over Keim with a normal Dulux masonry paint? READ MORE…

Yes you could do but you would lose a lot of the benefits of having a pure mineral based system.

If you are doing this commercially, or if you just want some reassurance, I would suggest you contact Dulux Technical Services for further advice.


17th Century house with various coatings and renders in different areas, unsure what paint finish to use? READ MORE…

We have just moved into a single skinned 17th C thatched house that has been extended in the 1700s and in 2006. The exterior walls need re-painting but there are various coatings and renders in different areas (lime render, concrete render, stonework). The whole house was last painted in a standard exterior paint (we think) but we are unsure to just refresh using something like a water based Dulux Weathershield or go for limewash? What are your thoughts? Steve

With a mix of materials as you’ve described the safest bet is probably to go with a standard water based exterior paint like Weathershield, as you suggest, particularly if the condition of the walls is reasonably sound.

If you are in doubt about the performance in certain places it’s worth doing small trial areas and leaving for a while to see what happens before committing yourself to a complete re-paint.

The only possible problem I can think of is where regular paint has been applied over limewash (as you suggest this may be the case)? It may hold OK at the moment but the addition of more coats can cause a failure of adhesion.

If this is severe you may have to scrape back to a sound surface and start afresh (a priming coat of regular exterior paint thinned with water will usually suffice).

For problem areas you may need to use a specialist primer such as Dulux Primer/Sealer or Alkali Resisting Primer – this should only be used in small areas though as it is oil based and will not allow any trapped moisture to escape.

External painting and re-rendering west-facing, coastal Bungeroosh walls. READ MORE…

Hello, I have bungeroosh walls which need external repainting and in some areas re-rendering. I am aiming to remove all the external paint and re-render and blown patches with traditional lime render ( no cement ). What is the best paint system to use, bearing in mind the walls are west facing and coastal, so take the full force of the weather ? Also would it be prudent to apply a salt inhibitor ? Thanks, Paul

Mineral based paints (as detailed above) will generally perform better in this situation but can be expensive and are difficult to apply. The ultimate option would be Keim Royalan which is a high performance mineral based system.

If you’re looking for a more standard approach Weathershield Maximum Exposure Masonry Paint has been developed for use in coastal environments and is a simple water based system.

If you want to use a salt inhibitor with a lime based render you’ll need to use an organic alternative such as Mystolene

PS. If you are just patching up an existing coating it shouldn’t really be necessary though?

Sandstone property where the masonry around the windows and doors has been painted with black pitch or tar! READ MORE…

I have an old sandstone property where the masonry around the windows and doors has been painted with black pitch or tar! Are there any paints available that would bond to this surface. Help, Andy

Acrylic primers can be used to seal bitumen based coatings to varying degrees of success. Zinsser’s ‘Bulls Eye 123 Plus‘ is the best of them but may be expensive depending on how large an area you need to cover. Once dry the wall can be painted with a regular masonry paint.

What is the benefit of either using an oil based masonry paint -v- water based? READ MORE…

Pliolite paints are often referred to as ‘oil-based’ although they are not the same as other oil based paints, such as gloss and some primers, you may be familiar with. They do have similar properties though, like a resistance to moisture. This may sound like a good idea but it can be detrimental to masonry walls as it will also trap any moisture already present beneath the surface.

Water-based masonry paints offer a fair degree of resistance to moisture, once dried, but are also ‘moisture vapor permeable’ – which means any damp trapped beneath the surface can dry out naturally.

This is especially important where the wall is a single thickness to prevent any damp working its way to the inside of the building.

Lime and mineral based paints also have this property and Keim explain the concept of breath-ability much better than i have done here . There is more on the subject here at buildingconservation.com

Anticipated lifetime of Beeck & Keim -v- Limewash on newly lime-rendered house? READ MORE…

I have a newly lime rendered house that I need to now paint and would like guidance on the anticipated ‘lifetime’ of Beeck and Keim v lime wash. Also do Beeck or Keim give any guarantees on their products? Christine

Lime wash is cheaper and easier to apply but will need re-coating every 2 or 3 years. The lifetime performance of Keim will depend upon the condition of the wall, skill of application and so on but if applied correctly you can more or less forget about it.

Keim offer a warranty on the adhesion, breath-ability and light fast nature of the coatings. They will need to visit the property and produce a detailed specification. There are no charges for the service and you’re under no obligation to go ahead. A typical warranty would be for 10 to 15 years.

To arrange this you’ll need to contact Keim via their website

Beeck offer a guarantee of up to 25 years against colour and UV degradation depending on the product used. For further details contact The Cornish Lime Co as they are the official UK distributors.

I need to paint garden wall which is breeze block what paint do you recommend? READ MORE…

Any brand of water-based masonry paint will do the job just fine.

Which is the best masonry paint to use when covering existing k-render? READ MORE…

K Rend can be over-painted with any regular masonry paint.

Victorian manor house rendered in Roman cement and painted with Keim Granital. READ MORE…

I live in an early Victorian Manor House that was rendered in Roman cement. There was an extension put on in around 1910 and a few small alterations since. In 2002, I scaffolded, repaired the render (4 parts sand, 1 part cement, 1 part lime or Keim Spachtel) and repainted using Keim Granital (cream in colour). Glenn

It looked great initially but in many areas the repaired render became friable and the paint came off with a layer of the cement repair, plus older repairs.

Also, areas of render that seemed solid but live, have become damp inside (18inch thick walls). Also, large areas have discoloured and now have a reddish hue. The roof has a parapet and the paint has largely come off the top of the parapet. I plan to repaint next year and am looking for a finish that will be more durable. Any ideas ?

Any paint system is only as good as the substrate it is applied to. If the render has become friable there may be several reasons for this which may not necessarily be a failing of the paint system?

I suggest you get in touch with Keim, since you have used their products already. They should be able to arrange an inspection and will give more specific advice.

Preparation and painting of garden walls for protection of brickwork/mortar. READ MORE…

I live in a ground floor Victorian terrace. Our back garden is walled on two sides by our property. The walls have 2 ‘skins’ and the outer external skin/ wall is in dire need of repainting. I have carefully repointed all of the brickwork and stabilised flaky areas with a solution. I am now almost ready to paint the walls. The previous paint is patchy but certainly covers all of the brick work in at least one layer or more. Please can you advise on the best preparation for he walls now and what type of paint I should use for best longevity and protection of the brickwork/ mortar. Thank you very much. Georgina

For a garden wall any standard masonry paint will do. 2 coats should provide a satisfactory finish. Just ensure the pointing has had time to dry out fully (a month should do it in the current warm weather) and prime the new cement with a very thin coat first.

Also spot prime the areas you’ve treated with a coat of masonry paint to build up the surface; then just repaint the whole area.

You may find the additional weight of new paint causes some of the old paint to lift-off. If this happens just scrape back to a firm edge; spot prime and re-coat.

Painted sandstone, primed with PVA and now bubbling. READ MORE…

I painted two sandstone posts at the front my house about a fortnight ago. I used PVA as a primer/sealer followed by two coats of Sandtex but now the paint is beginning to bubble why? Mark

Bubbling of the paint surface is usually a sign of trapped moisture. The problem with PVA is that it forms a film on the surface which will act as a barrier and prevent moisture from escaping.

You should really have just used a diluted coat of masonry paint as a sealer. Best thing to do now is just scrape off the bubbling as it occurs, allow the immediate area a bit of time to dry out and then touch up with water-based masonry paint.

Roughcast rendered walls letting in damp due to cracks and the wrong kind of paint. READ MORE…

We have a 1906 house with rough cast render (cement based with stones) applied over one layer of bricks to the first floor.

It’s letting in damp to the internal walls which we understand is due to some cracks and the application of the wrong paints in the past which haven’t let the trapped moisture out.One (expensive) solution may be to cut the render from wall, reapply the render with a membrane beneath (to prevent damp penetrating in the future) and then repaint…(?)

Another (cheaper) solution might be to try and remove the different paint layers and repaint with a good quality mineral paint or masonry paint. But how would you advise getting the paint off: heat gun, wire brush, a chemical…

Or would you say we may be better off going with the expensive solution, although I’m concerned about in case the render pulls the bricks beneath it… many thanks, Mark

Removing the render completely may not be necessary if the cracks can be repaired, it really depends on the overall condition? Either way, I’m not sure inserting a membrane is going to be a good idea as it will just lead to another problem with trapped moisture further down the line?

There is a common misconception that masonry paint should be entirely waterproof as this would cause more problems than it would solve. Ideally, and particularly with a single skin, the wall should be able to breathe on both sides, each with moisture permeable finishes applied.

In your case, it’s unlikely that the paint is at fault and that moisture is getting in via the cracks. If these can be repaired then this may be all you need to do and you should try this approach first before attempting to remove the render as this may, as you suggest, lead to further damage to wall beneath.

Bubbling render and paint flaking off, was it the wrong kind of paint? READ MORE…

I moved into a bungalow approx 18 months. Some of the rendering is bubbling and some of the paint has flaked off. It appears it was painted not long before i moved in. I have a feeling the wrong paint was used but am not sure. How can i can if it was the wrong paint or if it needs rendering again ? I will get a professional in to look at it but wanted to know more before i did. Carol

It’s unlikely to be the wrong paint as any brand of exterior masonry paint should perform OK if used properly. Masonry paint is formulated to allow normal levels of moisture to evaporate through the surface, it will always fail if the moisture level is abnormally high.

My guess would be that there was a high level of moisture already present. Maybe due to an underlying damp problem or if the render has been applied recently it hasn’t dried out fully before it was painted.

It may be possible to remove the flaking paint and then leave the walls to dry out naturally (ideally until the end of summer) before repainting. However, if the render itself is bubbling then this will have to removed and redone.

Decorative cement bands around windows and cills, over-painting gloss finish. READ MORE…

I am currently redecorating the front of our 1920’s semi detached house. The house has decorative sand cement bands around the indows and concrete cills, all of which have been painted with gloss paint. The external render is K Rend and would like to tone down the sheen of the cills and bands to compliment the K Rend finish. Can the gloss paint be rubbed over and painted with a weathershield masonry paint or does this need primed/undercoated to ensure it does not flake. Stephen

It’s worth emphasizing the need for thorough preparation. Ideally, use a wet and dry abrasive with clean water to abrade the surface and use a quality acrylic primer/undercoat if you want to be certain the masonry paint will adhere over the long term.

A masonry repair and crazed masonry paint. READ MORE…

I have a twofold problem with the exterior of my 1870s terraced house.

The protruding horizontal stone section of the portico is quite badly eroded and I want to save it but am wondering what product to use. A previous sand and cement repair has failed. Im looking into the confusing array of toupret fillers or would I be better off using a lime based product? I think it’s made of sandstone but I can’t be sure.

Secondly, I have crazed masonry paint on the stone sections surrounding my windows. Its quite difficult to scrape back to stone as the underlying paint appears to be a thick gummy paint that is very well adhered to the stone (which is in good condition).

I think the problem has arisen because of differential movement between old (oil based?) paint and the newer water based weathershield. How should I proceed?

The Masonry Repair
As you have found, repairs with sand and cement tend to fail eventually and can pull off even more of the original stone in the process.

Resin based fillers, such as Toupret Touprelith F, are good for general purpose repairs but can be too strong, leading to further damage.

Lime based mortars tend to perform better as they remain pliable and prevent less of a barrier to the free movement of moisture.

For deep repairs it may be worth using a reinforcement of stainless steel pins or non-ferrous wire mesh to give the repair material something to hold to.

When the repair is complete you can finish with regular masonry paint. I’d leave it a couple of months to dry out in depth though.

For advice on the use of lime mortars and stone repairs the Society for the Protection of Ancient Buildings (SPAB) and buildingconservation.com provide some excellent guidance.

Re the crazed masonry paint:
I’ve experienced this a few times and there isn’t a simple solution. It depends how old the paintwork is and whether it’s likely to stay pliable?

Ideally you should use a chemical stripper to remove all the existing coatings although this may be a difficult and messy job.

Alternatively, use a decent quality exterior filler (not a powder based filler) to surface fill the area affected and then rub down to a smooth finish. This will give a satisfactory result that may last for a few years or it may break down again in a relatively short period of time? It might be worth the risk – you just have to use your best judgement.

House on the seafront with faded pink masonry finish, what’s the best masonry paint for colour retention? READ MORE…

I have an Edwardian house directly on the seafront. The paint has faded from pink to nothing in two years. I would like to return it to the vibrant colour it was this year. Could you advise me as to the best prep materials and final masonry paint for this type of property please. Carole

The use of strong colours in coastal environments often necessitates regular re-painting. Dulux have a paint especially formulated for coastal areas although they make no claim about colour retention.

There are a few high performance coatings which do, namely

Keim – Royalan – Permarock – Dacrylate & StoColor

The only problem with these products is that they are expensive and not always compatible with an existing paint finish.

It may be necessary to remove this completely before commencing work.I would say Keim Royalan is your best bet. However, in all cases, it is essential that you obtain and follow a detailed specification from the paint supplier.

Poorly applied lime wash paint, wanting to maintain a bold yellow that is easily maintained? READ MORE…

We have just moved into a property which has had a very poorly applied lime wash paint. Our house is right on the road so need something that is easily maintained (ie washed down every year) as it has a tendency to get dirty. I have been recommended a Rust-Oleum Noxyde Primer and then the Murfill paint after, however we wanted to maintain the houses bold yellow colour, and I think murfill is only available in pastel colours. is there another product that you can recommend that covers the following or would you advise that we compromise on a different colour?:

  1. bold yellow colour
  2. maintenance of washing.
  3. previous limewash used so needs to be able to bond
  4. flexible and breathable (timber framed house)
    Thanks, Jess

I don’t know why Rust-Oleum Noxyde has been recommended as a primer but since you’ve confirmed this is correct I’ll have to admit defeat on that one?

Murfill may be appropriate but as you say the colour you want is not available then you may have to rule this out anyway? It may be worth contacting them or a distributor to confirm this though? The UK distributor is marcopolodecor.com I have no experience of using this product by the way, so bear this in mind please.

The only other alternative I can suggest is to use a regular masonry paint such as Dulux Weathershield. It isn’t as washable as you might like but there will be no problem obtaining the colour you want?

Whichever option you go for I would urge you to ask the company involved for a specific specification and ensure your painter follows it to the letter. Then if the system does not perform as promised they will be liable for the cost of putting it right.

Using masonry paint on a previously limewashed render. READ MORE…

Hi, we have a 1930’s semi detached house which is of a brick cavity construction. 6 or 7 years ago the original render was removed and re rendered in lime and then limewashed. It needs re limewashing now as it is showing signs of wear, hairline cracks and algae growth.

We would rather not use limewash again for various reasons, main being the look of the walls when its wet and damp (90% of the time round here) and the patchy drying compared to the rest of the street.

Would it be possible to use a water based masonry paint over the top of the limewash if we scrub the dirt and algae of first? Nick

You should try and remove the limewash finish if at all possible unless it is firmly stuck to the wall and not friable (powdery).

It is possible although any paint coating will only ever be as good as the surface it is applied to. Limewash is very absorbent and you may need to apply a couple of thinned coats of masonry paint as a primer first?

You’ll also need to ensure that any hairline cracks are filled and sealed. Araea affected with algae growth will also need treating with a suitable fungicidal solution.

I would advise you do a trial area first and leave it for a considerable amount of time before proceeding to a full a re-paint.

Maybe do the most exposed area this year and, if you don’t have any problems, do the rest next year?

Bubbling paintwork with salt deposits beneath. READ MORE…

We recently moved into an 1850s schoolhouse. Single skin brick walls which have been painted over the years with different paints, most recently macphearson powerkote.

It is now bubbling in patches and flaking especially at lower levels. Behind the bubbles the bricks have salt deposits.I have started removing the loose and flaking paint with a scraper.

What do I need to do to removes the salts, fill the gaps, and repaint to prevent this reoccurring. Neil

The salt deposits, or efflorescence, and paint bubbling suggests a buildup of excessive moisture.

Powerkote is a pliolite based paint which is not as moisture permeable as regular masonry paints and this may have exasperated the problem?

Scrape off as much of the existing coating as you can and leave the walls to dry out naturally.

Remove any salt residue with a dry brush as wetting it will just allow it to soak back into the wall.

The gaps are best filled with a lime based mortar rather than ordinary sand and cement as it remains flexible and is less likely to crack.I’d leave it at least 3 months before attempting to repaint.

And I would use a regular masonry paint – thinning the first coat so it soaks into the wall.

It’s worth considering also what is on the inside surface of the wall as the concept of allowing single skin walls to breath applies to both sides.

Stubborn patches of old paint on sandstone window surrounds and rust-coloured staining. READ MORE…

Ive been stripping layers of old paint off my Victorian sandstone window surrounds which don’t look like they’ve been stripped back in many many years.

Ive got most of the old paint off but there are some stubborn patches that I cant easily get off.

I was hoping to paint with something like Dulux Weathershield to help the sandstone breathe. Do I need to get all the old stuff off first or can I paint over it?

Also the very last layer I got to which is directly on the sandstone is quite gritty brown and looks rusty – could this be some sort of sealant on the bricks? I’m worried it might bleed through the Weathershield. Claire

If the odd patches of existing paint are firmly stuck you’ll be OK to paint over them. There is little, if anything, to gain by removing paint that isn’t defective.

Also, if the original paint is oil based there is also a risk that it has a high lead content. You certainly don’t want to be removing this unless you really have to.

The rusty patches could be from oxidising bits of metal in the wall itself. Or it may be just natural discolouration?

The stone surrounds could have been painted with any manner of paint bases but the fact it’s proving difficult to remove suggests there shouldn’t be a problem painting over it.

If you do get stains bleeding through you can use an oil based primer to cover the patches.

Use sparingly just to cover only the areas affected. This should stop any water borne stains from bleeding through any subsequent coatings.

Painting a newly rough-cast rendered wall. READ MORE…

I’ve just had our new extension roughcast rendered (today). Firstly, how long should I leave it to dry before I can paint it?

I will be using Sandtex fine textured masonry paint to match the rest of the house. Secondly, a friend has recommended that I use a stabiliser paint first. Do you recommend this or just a watered down first coat of masonry paint? Robert

I would leave it 12 months before painting, ideally, the weathering process will help remove any loose material and allow the wall to dry out in depth naturally. If you can’t wait that long then 8 weeks minimum – assuming the weather stays warm and dry.

No you don’t need a stabiliser– a thinned coat of masonry paint is just fine although you may have to brush off any loose material or efflorescence which has appeared, as is normal with newly dried cement render.

Stabilising primer is ONLY for small areas which have become loose and powdery – usually on old surfaces which have been damaged by excessive weathering.

Repairing and painting old masonry window cills. READ MORE…

We have a hundred year old brick house. The sills are in a poor state (masonry) and we would like to repair and decorate them. Numerous layers of paint is now flaking all over. We would appreciate any advice on filling, sanding, and ultimately the painting of them please? Daryl

In an ideal world you would be able to scrape off all the loose paint back to a clean stone surface. In the real world what usually happens is that you get some bits of paint that peel off easily and other bits that won’t budge at all.

If you can scrape back the loose coatings to a firm edge. And then sandpaper these edges down (so they are smooth and won’t stand out when overpainted) without loosening any further paint then you should be OK to decorate as normal.

Failing this you’ll need to strip it all off. However, most brands of paint stripper do not work very well when it comes to removing masonry paint. Grit blasting does work but isn’t practical for small areas.

An heavy duty paint remover will usually do the trick but you need to use carefully.

Peelaway is probably your best bet as it’s the easiest to use and is quite effective. Once you’ve got down to a clean stone finish you can repair any damage with sand/cement or use an external filler such as Prestonett.

Using a filler is easier as you can sand it down level when dry but you’ll also get a smooth surface against the texture of natural stone which is difficult to hide.

Sand/cement will give a more ‘natural’ finish but requires a bit of skill to get a level finish. If you do go down this route prime the area to filled with PVA to aid adhesion.

Once you’re happy with the stone surface you can start to decorate as normal. Apply a thinned coat of regular masonry paint as a primer and then 2 or 3 full coats to finish.

Blistering paint on a breeze block garden wall. READ MORE…

We have a garden wall between us and next door. It was built along with their extension so I assume breeze block and render. It is painted but the problem is, when the weather is wet, moisture seeps down from the top of the wall and causes the paint to blister. I assume the moisture gets trapped behind and cannot escape. Is there a solution? Alison

You are correct.Ideally the wall should have a sloped capping to shed water and a damp course at a high-level. It’s likely these details have been omitted through a combination of shoddy workmanship and cost cutting?

There isn’t much you can do about it, unfortunately. If the blistering is really bad it may be better to scrape it all back to reveal a bare wall surface. It will probably be less unsightly and will, at least, give the wall more chance of drying out.

Using Keim on a previously painted sandstone wall. READ MORE…

We have a 400 year old listed country house with sandstone ext wall previously painted with an unknown masonry paint. It’s in a sheltered inland location and the client is renovating to a pretty high standard all round.

The architect has specified Keim Royalan which from their website seems to be for harsh/exposed conditions. Even if we were to go with another Keim product, I wonder if it is worth the extra cost over Weathershield.

I’ve read it’s advantages – but does it really have more breathability colour retention, algae inhibition than Weathershield. I guess the key is that will it still look fresh in 4/5/6 years when due to the high aesthetic demands of the client, they may want to freshen up the building to look ‘pristine’ again.

If so, any extra cost now for a 20/25 year paint will be lost as they will re-paint anyway every 5 years. Wozza

You say the walls are already finished with an ‘unknown’ masonry paint – so we can assume it’s just standard paint? Overpainting this with Keim would be a complete waste of time and money.

Has the architect specified the removal of the existing coating or is just a case of quoting the most expensive option because it makes him/her look good?

Clarify if the existing coating is remaining before going any further. If it is then repainting with Weathershield is probably the best option.

Painting K-Rend with masonry paint. READ MORE…

We’ve recently had Krend and roughcast chips applied to our external walls. Unfortunately it has dried very light and the chips make it look a speckled finish. is our only option to paint over? If so, would Dulux Weathershield be best to use? Len

I have stated previously that you can over paint K Rend with masonry paint but as this has recently been done you would need to contact K Rend because it may affect any warranties or guarantees. Hopefully you’ll know which exact product was used. Don’t proceed until K Rend say it is ok, either by letter, email or with a product data sheet.

Painting a breeze block garden wall. READ MORE…

I’ve moved into a house with a breeze block garden wall (or perhaps cinder block I’m not entirely sure) that is probably a couple of years old and unpainted. It seems in good condition with no staining etc. I was looking at masonry paint to freshen it up. Is this the correct type of paint and what preparation is needed? Nick

Yes, standard masonry paint is ideal. Thin the first coat so it soaks well into the surface. The second coat may need thinning as well (although not so much as the first coat) as blockwork is very absorbent and difficult to paint.

You may need to apply 3 or 4 coats to get an acceptable finish, depending on the the density of the blocks.

Roughcast rendered wall covered in mould an algae. READ MORE…

My house has a white painted roughcast render finish and is in need of repainting. On the north facing and shaded areas there are green and black areas which on close examination I think is mould or an algal growth.

In some areas its almost like a miniature moss growth with 1mm filaments showing. It doesn’t brush off readily with a stiff brush. Other than this the surface is sound with no cracking or flaking and several layers of paint accumulation from previous painting.

Its probably 8 or 10 years since I last painted it with a water based “Weathershield” so it has done well, but it now needs doing again. What treatment do you recommend for the surface growth before painting, or will anti-fungicides in the paint formulation be sufficient to deal with this? Guy

You’ll need to treat the affected areas with a fungicidal wash such as Everbuild and ensure any algal growth is thoroughly removed before painting. (Dulux do a Weathershield branded version but I don’t think it’s worth paying the premium in this instance).

This is going to be a thankless task and may involve a few applications and a thorough scrubbing. But there is absolutely no point in repainting the walls until it has been done.

Anti-fungicides in the paint itself are very mild and will not have much effect with a pre-existing condition.

External masonry sealed with PVA and now blistering. READ MORE…

I’ve had rendered external masonry re-rendered in some sections as the builder bodged the job and a) he won’t come back b) I don’t want him back.

I’ve built the uneven surfaces with ronseal exterior filler, which I sanded back to create a seamless finish. I then sealed with water resistant PVA and painted over with textured Dulux weathershield (the original surfaces were dulux smooth weathershield).

My problem however is that the paint over the filled/sealed surfaces has bubbled in the rain. Do you think it’s the water resistant PVA that’s causing the problems?I will of course sand back the bubbled areas and possibly refill some areas.

Would I be better to apply a primer/stabilising solution before paint or can I simply paint directly over the filled areas? Not sure I should try another exterior masonry paint as I’ve lost faith in Dulux. Cheers, Paul

You are correct in assuming the PVA sealer is likely to be the problem. It doesn’t allow trapped moisture to evaporate, hence the bubbling. You can sometimes get away with using a diluted solution of PVA but it is always a risk.

A slightly thinned coat of masonry paint should suffice as a sealer. It may also be wise to wait a while for the exterior filler to thoroughly dry out in-depth before repainting?

Should I add PVA to masonry paint? READ MORE…

Should I add pva to my paint when painting on fresh render. A few people I spoke to recommend and some disagree.

If adding PVA to paint improved its performance do you think the manufacturers wouldn’t be already doing this? The ‘some disagree’ camp are correct, there is nothing to gain by doing this.

Painted walls appearing lighter during winter months. READ MORE…

We have a cottage which is painted a lovely grey colour (moved in last year) but we’ve noticed lighter patches appearing through the winter months. Neither of us noticed in the summer when viewing the house so wondering if its due to wetter weather? Its only on the front of the house and not everywhere. Kate

Some masonry paints will absorb a certain amount of moisture and will usually appear darker in shade, but the reverse can be true with some colours. You’ll always get this to a certain extent but it’s most noticeable if the walls are lime washed rather than painted. If it’s drying out OK without damaging the paint film there shouldn’t be a problem.

What are the pros and cons of rendering/painting exterior walls? READ MORE…

I live in a converted barn, with stone walls. The wall in question faces SW in quite an exposed position (half way up a hill). It was repointed (cement) some 5 years ago, to a good standard, but with pointing that is set quite deep (ie the stones are quite proud of the pointing – some 10mm or so).

I am getting some minor damp ingress on internal walls, particularly around window openings where internal stonework was replaced with blockwork when the renovation was done.

The windows are sound and the mastic around them in good condition.I have noticed that several other stone built houses in my area have painted directly onto the stone work and others have rendered the wall, then painted it .

What are the pros and cons of each option?. In many ways I prefer the look of a wall that has been directly painted on. David

As a rule, for best effect against driving rain, the pointing ought to be flush with the surface of the wall. Having it set back 10 mm might look good but it’s likely becoming a water collection point?

Rendering walls

The benefits of applying a render to the wall are minimal, other than providing work – which is often why builders recommend it. The drawbacks can quite serious though, even when it’s done properly – which it often isn’t.

The biggest problem is that moisture already present in the structure will have a much harder job escaping and this will lead to more internal damp problems and long term structural damage.

There is also a misconception that cement render provides a water-tight finish. The problem is that even after a short period time hairline cracks will develop and will draw in moisture via capillary action.

The water will track into the building and become trapped – further exacerbating the problem you are trying to remedy.

Painting walls

Of the two solutions this is the least worst. A coating of paint will help the building shed water while still allowing any trapped moisture to gently evaporate. In ideal conditions where walls are sheltered from the worst effects of rainfall it can often be the ideal solution.

It is hard to say how successful this would be in your situation though, I wouldn’t like to say either way but if you are set on doing something this is probably your best bet.In principle there is nothing wrong with allowing walls to become damp provided they are able to dry out naturally.

House rendered with K-Rend, can I change the colour? READ MORE…

My house has been rendered (K-Rend) two years ago, but I am not happy with the colour. (My error!) Is there anyway to paint over K rend rather than having it all chipped off and rendered from scratch. If so which type of paint would be most suitable? Karen

You can use a standard masonry paint over K Rend without any problems. However, since it’s only 2 years since this was applied there may be an issue if you need to claim under any warranty. I would check the conditions of any warranty or guarantee before proceeding further.

Cracks and dirt stains on Tyrolean rendered walls. READ MORE…

I had a medium rubbed tyrolean finish applied to all ground floor exterior walls and exterior chimney to ‘blend’ in an extension on a 60s detached house in 2009. We have now started to get dirt stains from weather drips on chimney cap and in other areas, along with fine cracks in chimney stack.The walls are very porous and I see a lot of wet patches throughout periods of rain. Can you advise whether I am best to brush, prime and paint, and be prepared to repaint every ten years, or get the builder back to redo! Paul

Fine cracks are inevitable over time and will result in ingress of water that becomes trapped. They need to be repaired either by raking out and filling with mortar or an epoxy based compound.Porous walls need not be a problem as such so long as the water can evaporate from the surface fairly quickly. You don’t say if the damp is working its way through to the interior but, if it is, painting should mitigate this to an extent.

What paint to use on brickwork? READ MORE…

What sort of paint should we use? I’ve just read on the dulux website not to apply their paint to brick? Most of the house has been painted before although as I said i have no idea what paint was used, then some of the peely patches are back to brick or back to older paint. The vast majority of the house is ok, like you thought the worst of the peeling is where the gutter was broken and also on the end of the house which is south-west facing and gets all the wind/rain/sun etc. Margaret

The advice by Dulux regarding bricks refers to ‘common’ and ‘fletton’ bricks which are not very porous and, indeed not suitable for painting. There is some confusion over the word ‘common’ as this applies to a type of brick rather than general definition of the same word.

A confusion not at all helped by the wording as it appears on their site, it has to be said.

Of course, your bricks may indeed be commons or flettons or some other kind of brick that shouldn’t have been painted but this is academic since the offence has already been committed. It may go someway to explain the flaking though?

Where the bare brickwork is concerned, if the initial coat is sufficiently thinned then there shouldn’t be a problem, especially since we are now dealing with aged bricks which will have lost a lot of their initial smoothness.

So, Weathershield masonry paint, or some other brand of the same, is the paint you need to be using.

Painting a mural on a plastic-like surface. READ MORE…

I have been asked to paint a mural on a prefab style outdoor classroom. The walls are a plastic – like surface, not exactly sure their composition. It has been suggested that I should use gloss paint but I was wondering if I could do it with masonry paint. Frances

Masonry paint, once it’s cured, isn’t very flexible so will lose adhesion very quickly if applied directly to a flat plastic surface. Using some kind of primer will help.

Specialist primers such as Dulux Super Grip or Bulls Eye 123 are pretty good, although they are expensive. It depends how long you need the mural to last for really? If it’s just temporary a bog standard acrylic primer might suffice?

Make sure the surface is as clean as possible first. Apply a single coat of primer followed by as many coats of masonry paint as you need.

Painting pebble-dashed walls. READ MORE…

I have victorian terrace that is pebbledashed that I want to paint. Do I need to use a breathable paint or is standard masonry paint fine? Also can I paint it now in Autumn or should I wait till spring? Thanks, Jay

Standard masonry paint is breathable anyway so you don’t need to worry about that. The ideal time to paint would be towards the end of summer so any moisture has had chance to evaporate. If I had to choose between now and spring though I’d opt for now.

Removed flaking paint on walls, is a primer necessary? READ MORE…

My house is a 1940 white rendered house and the paint is flaking everywhere. We should have had it painted a long time ago. My son has power hosed all the loose paint which is most of the walls we started off scraping and heat gun but there was just too much. Do I have to prime anything or just water down first coat of breathable paint or do I have to wait to let the walls dry out. Linda

If the paint that remains is solid and doesn’t scrape off easily (as you suggest) then you don’t have to worry about it. The bare areas can indeed be primed with a watered down coat of masonry paint. You just need to be sure that the walls have had sufficient time to dry out and, to save you asking, this needs to be for as long as you can wait really.

What’s the best modern breathable masonry paint for rough cast pebble dash? READ MORE…

Hi, I am looking for advice regarding the best breathable/micropourous modern masonry paint for a pebble dash (Rough cast) South facing wall on a 16th century cottage.

The wall details appear to be that the entire wall was rebuilt during the Georgian period (when an extension was put onto the house) of solid 9 inch double brick thickness with out timbers in the wall.the wall appears to be clearly of a cement based pebble dash, as I have used a low jet power wash for the flaking paint, and the render appears to be very grey in colour like cement and is very hard and not friable.

I have read about removing loose paint and had read that one needs to be careful with power washing as there needs to be a long period of drying out, which we will follow.

Anyway, I am looking for advice about the most breathable exterior masonry paint available that isn’t lime wash. the wall appears to be currently covered in approx 80% modern paint, as the bits that I have removed appear quite flexible still after all these years.Possibly there is a very durable lime based paint that would be long lasting?

However it would be going over modern masonry paint. Any advice appreciated. Richard

Since you say most of the surface is still covered with regular masonry paint I would stick to this. Any paint system is only as good as the surface it’s applied to at the end of the day.

High performance mineral based paints do offer superior performance but only when applied to a bare wall. In your specific case these would be a waste of money. Another problem you may encounter when re-painting is that some of the remaining coating may become loose as a result of the extra load imposed by an extra coat.

If you are using water based masonry paint this isn’t going to be so much of a problem – a bit more work and a little extra cost at worst.

I can’t say this will happen, or to what extent, but it isn’t uncommon.

Can I use exterior masonry paint on interior walls? READ MORE…

Hi, I have recently painted my window ledges with Dulux weathershield masonry paint in brilliant white and it really is brilliant white. Unfortunately I have also painted the interior of my flat using a Dulux matt interior paint in brilliant white but it is more of an off white/cream colour and looks dull. Do you know if it would be safe to use the masonry paint on interior walls as its the bright white I need or due to the chemicals would it be harmful to breath in? I have a very low budget so didn’t want to buy more paint! also if its not safe, what interior paint would you recommend to be a really bright white matt finish? Many thanks.

Exterior paints, generally, can have a slightly higher level of obnoxious contents because they are applied in the open air (as a rule). However, the differences are minimal, although you may notice a stronger odour.

Paint products are considered harmful to health if they contain a high level of Volatile Organic Compounds (VOC’s). The VOC’s limit for exterior masonry paint is 40 grams per litre. The VOC’s limit for vinyl matt emulsion is slightly lower at 30 grams per litre.

Dulux Weathershield Masonry Paint has a VOC content of 10 grams per litre. So is easily within the safe limits for both.

Safety data sheets:

It’s worth noting that the formulation for both types of paint differs quite a bit due to their intended uses. So it’s likely you’ll get a much less smoother finish if you use an exterior masonry paint. It’s certainly worth doing a small trial area before committing yourself.

As a general rule white paint sold as ‘Brilliant White’ is about as white as you’ll get. Paints labelled as just ‘white’ often have some colour added to make them less bright – hence the dull comparison.

I used exterior masonry paint for inside a cupboard, will this affect my health? READ MORE..

I have painted an interior clothes cupboard with some left over dulux westhershield masonry paint. size 47inchx47inch. I’m now worried this is bad for my health. Will it be ok or should I paint over it with white emulsion? Lesley

Paint products are considered harmful to health if they contain a high level of Volatile Organic Compounds (VOC’s). The EU regulatory limit for the amount of VOC’s for this type of product is 40 grams per litre. Weathershield Smooth Masonry Paint contains 10 grams per litre – so is well within this safe limit.

Would masonry paint fill hairline cracks in the wall? READ MORE…

The Tyrolean finish seem to be the problem as it has not been applied thick enough for a consistent covering. The cracks around stress points can be repaired so that’s not too much of a problem.

Would a good quality water based paint finish fill the hairline cracks and would it then withstand severe weather hammering at the wall. If we go down this route, roughly how long before a repaint? Roger

Paint will fill some cracks but I wouldn’t recommend relying on this method as they will open up again in no time at all. The cracks really need to be repaired properly by raking out with a sharp blade to make them wider so they can then be filled with a cement mortar or epoxy resin filler.

If the repairs are done right there is no reason why the paint finish shouldn’t last at least 3 years or more before it needs redoing.

Painting exterior stone with gloss paint. READ MORE…

I have an old terraced house. It has exposed “stone” above and below the window frame on the outside. I want to paint the “stone” with black paint with a gloss finish. Can you recommend a suitable paint please? Chris

This specification is for small areas of external stonework such as window ledges and lintels. The success of this system depends upon the level of moisture already present. Any well known brand of paint will do.

First coat of alkali resisting primer (available from any decorator’s merchant).
1 or 2 coats of regular undercoat (dark grey)
1 or 2 coats of regular black gloss to finish.

Repainting glossed stone window cills. READ MORE…

My grade 2 listed 1780s house has stone window sills. We are having the outside of the house painted using masonary paint and the windows painted using Dulux weathershield gloss. The sills were previously painted but it has been scraped off. Should we use the masonry paint or seal and use an oil based paint? Susan

Whichever finish you prefer will work either way. Although an oil-based finish will assist surface water (rain) run-off – so I’d consider this if the sills are particularly exposed?

Should I use an oil-based paint on rendered walls? READ MORE…

Hi , Have just purchased a 400 year old pub that has the exterior walls built of chalk with a brick outer layer. Leaving a small cavity between, unfortunately it has been rendered on the road side (which is only a pavement width away) with scratch coat and then coloured a cream coloured second coat, presumably snowcream.

I do intend to remove the lot in the future and re render with a lime render, it has also been painted many times since being rendered in the 1950’s .

As it is so close to the road, would you recommend painting with an oil based paint to enable me to wash it monthly to clean off the road traffic dust.? I have just painted it with a water based coat from b and q, temporarily. Angus

I wouldn’t recommend painting with an oil based paint or sealer as any moisture within the walls is going to become trapped. This will, inevitably, lead to further problems.

A product you may want to consider is StoColor Lotusan which is a dirt resistant finish for commercial buildings. You will need to contact Sto to check whether this is suitable for your requirements?

Walls already painted, do I need a primer and undercoat? READ MORE…

Hello. I have a customer who wants a few chimneys repainted, he has requested that i use a primer, an undercoat and a top coat. Also that all 3 coats have to be the same brand and compatible.

The wall already has white masonry paint on it. I was planning on just washing it down treating it and putting a few more coats of dulux or sandex on it, is what he is asking a correct way to repaint an already painted masonry wall? It seems excessive to me but wanted to check it out before quoting the job.

Also what brands do a primer, undercoat and top coat to go together? Many thanks, Dave

2 coats of masonry paint is all you need, provided the existing paint is in reasonable condition.

Blockwork garden wall with a chalky coating in places. READ MORE…

I have a breezeblock supporting garden wall ,it has a chalk like coating in places i want to paint it can you advise on what is best to use? Wendy

It is likely the chalky coating you refer to is efflorescence (migration of mineral salts to the surface) which can be caused by natural drying-out or may be an indication of a persistent damp problem.

Garden walls are typically not constructed with painting in mind so you may have to accept that you are never going to get an ideal finish.

If you really must paint the surface then try and remove the chalky deposits with a dry brush as much as possible before painting with a standard masonry paint, the first coat of which should be thinned so it soaks in to the surface.

The worst case scenario is that you’ll experience problems such as patches of staining, some paint flaking off and/or a re-occurrence of the efflorescence – all of which may be a nuisance but one you may prefer to the alternative of leaving the wall unpainted?

Repairing roughcast render and repainting with a breathable paint finish. READ MORE…

Hi, I live in an Edwardian semi detached property of solid brick construction with roughcast render. Prior to purchasing the property 2 years ago, the previous owner had carried out some repair work to cracks to the side elevation, which had been causing internal damp problems in a bedroom (the damp seems to be resolved – for now anyway). They also had the exterior completely redecorated, in a colour I am not personally keen on, using Sandtex masonry paint.

Our surveyor when we purchased the property advised on hacking off any defective render to help the wall to dry out, refinishing with a lime mortar based roughcast render and painting breathable coating. I’m now keen to redecorate the property (in a colour I do like!) it would obviously make sense that any further repairs to the render are done prior to redecorating.

What would your recommendations be for dealing with such redecoration. The condition of the render on the front and rear is ok, it’s really the side where some of it’s defective.
Would removing all the existing paint be sensible – assuming a breathable paint / lime wash over Sandtex and other layers of unknown paint is not really suitable?

If so, what would be the best way of removing it, without creating more problems for myself – e.g. would sandblasting damage the roughcast?

Or would another layer of Sandtex paint in a colour I do like (or Weathershield or similar) be ok? EJ

Since you say the damp problem seems to have been rectified I don’t think there is going to be that much benefit in going to extremes? Refinishing with a lime based mortar may well be the ideal solution but, if the level of repairs currently needed are minor, it may not justify the time and expense?

I suggest repairing the defective render like for like and re-painting with Sandtex or Weathershield. If you do experience problems with damp later on you can go down the route suggested by your surveyor but, from what you say, the chances are you may not need to?

Of course, your surveyor is charging you for advice and has liability to you in this regard if, after following his guidance, you still have problems. I am giving you free advice with no liability so you need to bear this in mind also.

Rendering over an existing paint finish. READ MORE…

We have a long garden wall that has been painted with Dulux Weathershield and is still in good condition. However, we would like to have the wall concrete rendered so that it is all smooth. Will we have any problems doing this – and if so how do we remove the paint? Gill

To render over paintwork you will need to provide a key for the cement to grip to. This doesn’t mean you would have to remove the paint but you will need to score the surface. Another way to do it is to mechanically fix a fine wire mesh to the surface. Anybody undertaking this work for you should already know this.

I will warn you, however, that some bright spark will say you need to apply a bonding coat of PVA, or something similar, for the render to stick to. I’d advise you strongly not to listen this advise since you’ll be storing up problems later down the line.

Hairline cracks appearing in a newly applied K-REND coating. READ MORE…

Hairline cracks in new k rend ! which paint to cover and would hide any new cracks after painting please help , mean advised that the flexi paints such as bedec or weathershiled extreme ?? would do the trick? Joe

In all honesty, painting over the cracks is likely to prove to be a waste of time and money in this case. Sadly, problems with Krend seem to be all too common and you should take this up with them.

Thanks , do you mean that it wont work on any surface or just krend ? we have bought mend rend to fill the hairline cracks but wondered if the paint may have covered it without ? READ MORE…

The advanced exterior paints you mentioned do have a degree of flexibility but it’s not something you want to rely on too much. In the instance of new render been applied it’s best to wait to see if any minor cracks develop into something worse before painting.

To an extent, you can always expect some cracking as a new render dries out but, in your case, I think it’s best to refer the matter back to the contractor and supplier in case there are any warranty issues to consider.

I think the problem with K-rend is not so much the product itself but with the contractors who apply it; they often don’t have a clue what they are doing and will try and walk away from any problems.

Putting this back to K-rend directly ought to get the matter resolved without you having to bear any further expense. They market their coating as some kind of miracle solution so let them put their money where their mouth is.

Recently painted walls with brown stains coming through. READ MORE…

I have recently painted rendered walls with a water based masonary paint and now 5/6 moths on the walls are starting tow seep though brown. What could be causing this and how do I rectify the problem? Tam

If this a large scale problem, not just isolated to few random patches, the most obvious explanation is iron pyrite contamination. This happens when the sand used for the render has a higher than normal content of iron sulphides which then oxidises (or rusts) when exposed to the environment. Painting walls with water based paints will accelerate this process and/or make it more visible.

In short, for severe contamination there isn’t much you can do about it other than to choose a darker shade of paint so it’s not so obvious. There are chemical treatments you can use but I don’t generally advise this as the results are unpredictable and can even cause more problems.

Using limewash or mineral-based paint over existing painted walls. READ MORE…

I have to recommend a masonry paint for a project I am working on. It is a 5 story Georgian terrace in London. It is currently painted, but needs updating.

As the house was last painted in the 1990s, would it be beneficial to now use a limewash or mineral based paint rather than weathershield or sandtex.

There are some damp issues in the basement and ground floor, so I want to make sure I am suggesting the best paint for them. I dont really want my clients to pay a huge decorating bill if the eco, mineral type paints will not make any difference or have greater longevity than weathershield. Louise

Since you suggest the house is already painted, it’s almost certain this is standard masonry paint. In which case there is nothing to gain by using anything else, as any paint is only as good as what is beneath it.

Walls with traces of bitumen on the surface. READ MORE…

Hello, the back of my garage and a side wall have bitumen on them from a lean to shed that I have pulled down after we bought the house. Do I need to deal this before I paint the walls? If so what’s best to use? Shaun

Bitumen always causes problems; firstly, unlike paint, it doesn’t fully cure so you get a lot of movement which will lead to cracking and shrivelling. You also have a problem that it becomes soluble in reaction to some paints so you get dark brown stains working their way to the surface.

There are two kinds of paints that you can use as a primer, with varying degrees of success. The cheapest option is regular acrylic primer/undercoat, or, for a bit more money, you can use Zinsser 123. Neither is a perfect solution but, as a primer for a garage wall, might be good enough?

What is the best masonry paint? READ MORE…

What is the best masonry paint? Sandtex? Dulux? Any recommendations would be gratefully received. Thank you, Jamie

There isn’t an honest answer to this question since there are so many variables; one brand of paint will outperform another in some situations and visa versa. It also doesn’t help that there have been no authoritative tests done. From a trade point of view it mainly comes down to experience and personal preference.

For regular domestic use you won’t find much difference between Sandtex, Dulux or any other major brand you can think of. Obviously avoid the really cheap own brand stuff, such as Wilko’s, and go for a trade paint rather than the consumer equivalent.

Other than that it’s just a matter of getting whatever is the best deal at the time.

What paint to use over limewash in a cellar? READ MORE…

What should I use to paint over lime wash in my cellar and what preparation do I need? Bev

Firstly, I wouldn’t recommend using anything that’s going to seal the surface since you’ll just encourage the retention of damp which will, eventually, cause problems. So the obvious answer would be to apply anther treatment of lime-wash. As an alternative you could use a clay based paint such as Earthborn Claypaint but it’s expensive.

There are products designed to be used in cellars, Dulux Cellar Paint is one, Zinsser Watertite is another. But these require the surface to be properly sealed first. This only leads to further problems because the walls are going to be already damp and very few sealers will adhere properly. So no matter what you paint over the top the coating is going to fail eventually.

The most common answer you’ll get for this question will be something along the lines of using a thinned coat of PVA and two coats of contract matt emulsion. Again, it will look fine for a while but soon start to discolour, bubble and flake off. Or, maybe use a fungicidal matt emulsion that costs a fortune and doesn’t make much difference.

Many, many years ago I worked for a contractor who’s main line of work was repainting pub cellars. We always used an expensive ‘cellar paint’ that was horrible to use but gave a great result. You could go back a year later though and have to do it all again.

Textured paint finish is uneven, what’s the best remedy? READ MORE…

We’re having our 1930s house repainted at the moment. The render is sound, but we have a few hairline cracks, a fair bit of peeling paint, and some uneven patches where new windows etc have been put in.

Our painters suggested using a paint with a lightly textured finish to give a more even appearance, my husband said yes while I was at work. The effect looks like they have just put sand in paint. The texture is gritty and uneven – I am so unhappy with it! I knew that there was no way we would get a smooth finish, but this is much worse than any crack.

What’s the best way to remedy things? Re-rendering is out of the question. I wondered if telling them to put two coats of Sandtex fine texture would even things out a bit – what do you think? Sophie

Either they have thinned down the paint too much or not stirred it thoroughly enough? Two coats of a good brand textured paint should improve things if it is applied properly – don’t pay for the work if it isn’t.

How long to wait before painting a newly rendered wall? READ MORE…

We are having the old pebble dashing removed and replaced one our house. It will then be painted with Sandtex Masonry Paint. My question is how long should the new render be left before painting? I have heard everything from a few days to 6 months! Rod

As long as possible, six months minimum.

The guy at Sadtex has just come back with 6-8 weeks. Seems there is no fixed answer to this. READ MORE…

There are too many variables to consider. Such as: how thick is the render, what is the state of the wall the render is applied to, what’s the weather like, and so on.

The reasons for waiting as long as possible are, obviously, to allow plenty of time to dry but also to wait for any minor cracks to appear so they can be repaired.

Just as an update to this, I waited about 4 weeks for the reader to dry out, the weather was dry. I use a damp meter to check on drying out and when all was at around 4% I applied two coats of Sandtex paint, undiluted. .One year on and all is well

Thanks for the update

Yellow patches appearing on painted stonework. READ MORE…

Hi I am in the process of painting an old farmhouse which consists of never painted or treated stone which is pointed. I used a first coat of Sandtex smooth masonry paint as a primer and then a coat of undiluted paint.

After two days yellow patches started showing through the paint. About a week later a further coat was applied and this seemed to get rid of the patches.

However about three days later and after a day of rain, the patches started showing through again.Prior to painting we ensured the stone was sound and it was brushed down and any moss ( very small amounts only) were removed.

The stone was, as far as we could tell dry before we started.I would be grateful for any advice. Martin

It could be one of two things, or a combination of both.

It’s possible the stone has a high degree of internal moisture or it may be contaminated with a waterborne substance that’s migrating through the paint.

The former is usually obvious because the staining will be in a line that corresponds to where the stonework is most exposed to the elements (like the west facing side) or ingress of damp such as immediately above ground level or below the roof line. In which case ensuring any obvious defects are rectified and allowing the walls another year to dry out may solve the problem. The stains will still be there to an extent but you should be able to repaint without the problem recurring.

The latter is more likely an explanation where the staining is in randomised areas with no obvious pattern. Unless the patches are minor there isn’t much you can do without compromising the long term performance of the paint though.

A coat of stain blocker or a bit of oil based white undercoat will sort any odd patches but for large areas a darker colour finish may be your only option.

Thanks for you reply. Think its possibly the latter as the stains are random but not just small areas that can be covered up with stain retardent and then touched up. I have done areas around windows withe black masonry paint to achieve an old farmhouse effect and that is fine so perhaps a darker colour is the answer. Once again thanks for help.

You’re welcome

White sand and stone render turning red, what to do? READ MORE…

I have white sand and white stone render that is only 4 years old, the side elevation has turned red due to the rain etc….can I just paint over this or would I need to use hyperchloride to remove first. Also if I do paint it, will the red return within a few years? Jeannine

There are various chemical solutions that will bleach the red staining but it will come back every so often, so it isn’t something worth doing unless you are willing to repeat every year or so. I have heard it said that the staining will reduce in severity over the years but there is no firm evidence, other than anecdotal, to support this theory.

As a general rule, chemical cleaning solutions should only be considered as a last resort as they can cause more problems than the solve, mainly because you don’t always know how they will react with different materials. If you do go down this route ensure the people doing the work are qualified and experienced – with sufficient guarantees in place should problems occur afterwards.

Painting isn’t a solution since you would need a stain blocking coating for it to be effective and this would be detrimental to the breathability of the walls.

Removing flaking paint but some stubborn patches. READ MORE…

We live in a cottage built in 1780 with several subsequent extensions. There are only 2 original stone walls left (fortunately). We have recently experienced damp patches on the inside of one of these walls and the cement render behind our wood burring stove is falling off the wall. Inspection of the external walls has revealed they are pretty wet – especially the north facing that gets a lot of snow (we live at 1000ft in the Scottish borders) – behind the coats of paint and cement render/pointing that is one them. There is no damp course.

The paint appears to be 2 coats of grey primer and 1 or 2 topcoats of white standard masonry paint. We’ve decided to strip off the paint and cement and repoint with lime mortar. However, whilst the paint is coming off easily in some areas, it seems impossible to remove in others. A grinder with an abrasive disc works but is leaving scratches on the stone. Do you know if a heat gun could melt the paint off?

Also, we were planning to leave the stone bare once it is stripped and repointed (so it can breathe) but if we can;t get all the paint off then the only option will be to repaint. In this case, do we need to apply a lime render and then lime paints? I am worried about whether the lime render and lime paint will stick well enough to patches of masonry paint? I have read that adding casein could help, or that silan paint would stick to it. Is this correct and if so, which would you recommend? Finally, the rest of the house (wet dash render) is a pale cream colour – do you know if we could tint lime / silan paint to match? Sarah

The most effective way to remove the stubborn patches of paint would be with grit or sandblasting although this would leave you with patches of very clean stonework contrasting with the existing finish. This may be as aesthetically displeasing as having patches of old paint though?

Chemical paint strippers can work – it is very much a case of trial and error though. A poultice system such as Peelaway can be the most effective option though.

See also: removing paint from walls

If you have to resort to painting the walls lime paint would be suitable although you’ll need to prime the painted areas with casein first. A silica based finish, such as the one you mention, should adhere OK without pre-treatment although you should seek advice from the manufacturer before you proceed.

You can buy universal tints from trade paint merchants suitable for most finishes. With the case of specialist paints though it’s always wise to try a small sample first.

Using an oil-based masonry paint to waterproof the walls. READ MORE…

I have a house with /roughcast cavity walls which a few years ago were filled by blowing into the cavity an unknown type of insulation (probably glass fibre). I recently had a conversation with someone who told me he has had major problems with dampness in his house which was apparently caused by fibre insulation which had soaked up moisture and became like a sponge (this was only discovered after removing some brieze blocks to identify the problem)

I want to apply a waterproof paint barrier to avoid similar problems in future and am thinking an oil based paint might be the best option as it should be completely waterproof. I understand that this would also prevent any moisture within the walls escaping, but since I live in the wet Scottish Highlands I’m thinking there is more likelihood of the walls absorbing moisture than releasing it.

Which type of paint system would you recommend? Alexander

The correct solution would be to remove the insulating material. There is no paint that will provide a waterproof barrier since moisture will penetrate via hairline cracks externally. Normal atmospheric moisture will also work it’s way through the internal walls and become even more trapped. The effect would be like wearing a cheap cagoule when you getter wetter from perspiration than you would have done from the rain without it.

If you don’t want to remove the insulation and also want to provide some protection from the elements a standard masonry paint is the answer.

Painting a damp retaining wall. READ MORE…

In the yard of our property there is an 8ft high retaining wall which probably has an old stone wall directly behind it and earth behind that. The visible retaining wall face is unpainted breeze block.

In order to brighten up the area (the views from the downstairs back windows of the property are this wall), I’d like to paint the breeze block wall. However, it is damp and mossy in areas as I guess moisture comes through the wall.

I can pressure wash it to start, but wondered what treatment and paint I could use. I don’t want to trap the moisture in the wall behind the paint. Zoe

There isn’t a correct answer to this problem since the amount of damp in the wall is going to be far more than any masonry paint can cope with. If you can provide a means of drainage at the base of the wall it will help, a bit. If there is nothing there already you can drill some holes in the first course of blockwork to give any buildup of moisture some means of escape.

The two options you have then are to leave the wall unpainted (ideal) or paint it anyway, accepting that it’s only going to be a temporary fix.

Assuming you opt to paint it you can clean off any mossy areas with a fungicidal wash, or with a solution of household bleach and water.

Allow as long as you can for the surface to dry and then paint with any standard masonry paint. There is no point spending more than you have to since it isn’t going to make any difference in this situation. I’d steer away from the really cheap stuff but an own brand paint from B&Q or Wickes will suffice.

It’s likely the end result will look fine for the rest of the year with mould coming back eventually and paint flaking off in the worst affected areas. If you can live with this and accept you’re going to have to repaint the wall every year or so then fair enough.

Newly rendered wall with black flecks of bitumen appearing. READ MORE…

We have a newly built retaining wall in our garden, all done correctly no expense spared. We had it rendered about 5 weeks ago and are allowing 3 months for it to dry thoroughly, maybe longer given the appalling weather.

But a problem has appeared as it is drying. On large areas of the wall little black flecks of what we have been told is bitumen in poorly washed sand used in the render have appeared.

I have patiently dug most of these out with a Lancashire potato peeler but they seem to be coming again. I am planning to use Little Green masonry paint and their advice on a new wall is not to use a sealer, but I fear if I don’t at least seal over these black spots they will keep coming through the paint.

Please do you have any experience or advice about this type of problem. Debbie

I haven’t experienced this problem myself so I don’t know for sure what the solution is, other than removing the render and having it done again. However, I also would advise against using a sealer as this is likely to cause more problems than it will solve.

What I would do though is leave the wall to weather for a full year before attempting to paint it. This will give any contaminants that are going to work their way to the surface all the time they need to do so. The only downside is that you will have to tolerate the sight of an unpainted wall for a year longer than you intended.

When you do come to paint the wall I would also suggest doing a trial area first and waiting for a while to see if you get get bits of bitumen staining through. It may well be that any bits of staining you do get can be spot treated without any major detriment. In which case a water based stain blocker such as Zinsser 123 will do the job.

Rendered wall with 2 courses of brickwork at the bottom. READ MORE…

I have a rendered wall with two rows in height of bricks underneath render at ground level. These bricks have been painted red which I assume was not a breathable paint as the bottom level of bricks on ground have bubbled up. Should I be worried and what can I do about this. Steve

This is a fairly common situation and brickwork at this level is often painted red or black to make it more aesthetically attractive. It’s not ideal but since the brickwork is likely to be below floor level it isn’t going to do any harm internally.

So, to answer your question, no don’t worry about it.

Uneven patches where paint has been removed from the wall. READ MORE…

I have been preparing a west facing exterior wall, approx 14ftx24ft. The paint on it had flaked in places and bubbled (possibly due to water getting into the render through the cracks or because it was a cheap paint applied by the previous owner). I have scrapped most of the paint off the wall and used a blow torch to get rid of some of the bubbly patches that were difficult to remove.

I have filled all the cracks with Tourpret exterior filler and some smaller cracks with Polyfilla exterior. The surface is now prepared, however there are some patches of the original paint that I cannot remove, so the surface is a mixture of bare render and the “base” layer of the previous paint. I can remove bits of it with a pressure washer but cant get all of it off without a lot more work.

Having painted a test patch over an area, Im worried that I will get an uneven finish where the paint goes over a bare patch of render and then a base layer of the old paint. At the moment you can clearly see the base layer sitting slightly proud through the first coat of paint.

So, is there a solution other than pressure washing the whole wall for a long time to get all the old paint off (as much as poss) or would a clear matt masonry paint (Sandtex) eventually hide the imperfections after 2/3 coats? We don’t want a textured paint and ideally don’t want to re-render the wall. Paul

The only practical way to get the result you want is to just paint the bare areas until the levels are uniform and then finish with on or two coats overall. This may not be easy if there are multiple remaining patches of paint and it also means you use a lot more paint than you originally intended.

Alternatively keep re-coating the walls overall until the difference in paint levels evens out – this may need multiple coats to achieve a satisfactory finish.

There are seldom easy answers to these problems which is why you don’t ever meet any wealthy painters.

Is there such a product as an oil based masonry paint? READ MORE…

Is there such a product as an oil based masonry paint. If so could you let me know if it is better than a water based masonry paint such as Dulux Weathershield. Also could you let me know who manufacturers it. Phillip

Yes, it’s widely known as ‘Pliolite‘ or ‘all-weather’ masonry paint, Pliolite is a rubber-based resin developed especially for use in paint products. Most of the major paint brands have a version available.

The only valid reason for using these products is that they become surface-dry much more quickly than water-based products. This is a useful property if you have to paint a wall when the weather isn’t predictable and rainfall is a possibility. In a domestic situation you can always wait for a better time but in some commercial situations the job has to be completed by a certain date regardless; that’s where these products come into their own.

Generally speaking, a water-based paint is always better. It’s easier and more pleasant to use, is moisture vapour permeable (so doesn’t trap moisture in the fabric of the building) and, when dry, remains elastic for longer than an oil-based product would.

What is the correct paint to use on external wall insulation? READ MORE…

Where external insulation is applied it will normally be finished with a proprietary render. In most circumstances you can over-paint this with regular masonry paint. The exception would be where the render used is supposed to be a finish in itself.

In all circumstances though, you are best checking with the manufacturer of the system used and ask what they specify. This way you will not be in breach of any warranties or guarantees.

I would be careful of asking the actual installer though as the answer you’ll get is highly likely to be unqualified and wrong.

Is there any particular masonry paint that will withstand dirt and pollution more than others? READ MORE…

We have newly rendered walls on our house that is on a busy road in London. As it is in a conservation area, the walls have to be painted white. Is there any particular masonry paint that will withstand dirt and pollution more than others? Elizabeth

There are commercial products available, known as ‘self-cleaning’. They are formulated so dirt can not adhere to the surface and is washed away whenever it rains. They can be quite effective but are more expensive than regular masonry paints.

StoColor Lotusan is a popular brand, for example. Johnstones Self-Cleaning masonry paint is another option which is more widely available.

Painting masonry window cills with WeatherShield. READ MORE…

Hi. Apologies in advance for all the questions but I want to do a good job and repel the previous owners bad jobs! We have a 1930’s semi and we are looking to paint the masonry windws sills and door lintels etc. Some masonry sills have previously painted.
The bottom sills are flaky so I have rubbed these down with a surface preparation wheel attached to a drill to remove any flakiness. I have not managed top take it all the way back to bare masonry.

  1. Would I be ok to use Dulux Weathershield as opposed to a masonry paint as its not a true masonry surface anymore.
  2. What primer/undercoat would I need (if any)
  3. Where the upper sills have been painted and the paint is still sound, can I reapply a new layer of Weathershield or do these need priming/prepping in any way?

Stone window sills and lintels are often not painted with masonry paint so it’s difficult to give you accurate advice. Since you say the existing paint is flaking though, I assume a traditional gloss paint has been used? This can be a good idea for window sills especially since it repels standing water much more readily than regular masonry paint.

You can, however, use any kind of paint finish over the top although you’ll need to use a primer that will promote good adhesion. The previous use of a ‘preparation wheel’ may be problematic though (assuming it was the wire brush type) because bits of wire become embedded in the surface and cause staining which can be difficult to get rid of.

For these areas there isn’t that much advantage to be gained from using Weathershield as opposed to a cheaper option, especially since they have been painted before.

If the existing finish is indeed gloss then you can paint the upper sills with a coat of undercoat and a coat of gloss (rub down with sandpaper first). The lower sills may need priming with an alkali-resisting primer if any bare stonework is showing through (only prime these areas, not the whole lot). Then undercoat and gloss as normal.

If the finish is a flat masonry style paint you can paint the bits that are in good order by simply applying two coats. The bits where you’ve done a lot of preparation may benefit from an adhesive-style primer such as Zinsser 123. Then apply 2 coats as normal.

Which masonary paint would you recommend to cover haarling? READ MORE…

Which masonry paint would you recommend to cover haarling? I have huge patches to cover where there were deep cracks. Builders have sorted it all out but exterior house walls all need done. I would be very grateful for any advice and could a very good non professional do it? Marjorie

The traditional way would be to use a lime-wash. It isn’t difficult to do and to get a good result but it isn’t like conventional painting so it’s just a case of learning via trial and error.

Rather than attempt to give you instructions, I’ll point you towards some other websites that explain the process better:




Painted Baumit rendered walls and colour differences. READ MORE…

We live in a partially cement rendered bungalow with bradstone detailing. Last year after some building work we had some of the walls (including partial walls) re-rendered with Baumit. We have got to the stage where we are painting and getting conflicting advice.

We have tried both dulux and sandtex on both the old (finished in sandtex) and new render to find that the colours are taking quite differently to the two surfaces and have spoken with Keim who have said that there product will go over both, my worry is that there will still be the colour inconsistency and we could be making an expensive mistake.

Should we use some sort of base coat over the old sandtex, which to be honest is in good condition and finish everything in Keim or could we then use Dulux or Sandtex as they will be the cheapest option. Any advice welcome. Thank you, Bentley

It sounds like the inconsistency with colour is a result of being applied to two different textures? The way light reflects off a surface will have a slight impact on the way the colour is perceived.

On two separate buildings it wouldn’t be noticeable but on the same wall or a connecting wall it becomes obvious. It’s something you see often where walls have been repaired and the texture is never quite the same as the original.

Assuming this is the case, you are right to think that using any other kind of paint would be a waste of money because the end result will be the same. David

Repaired stone window surrounds with blotchy, dark patches. READ MORE…

I have an ordinary mid-terraced house in the North West. My exterior sandstone windows were tatty and crumbling, so a stone mason repaired them and painted them with 2 coats of cream masonry paint.

A few days later, some areas of the stone began to look blotchy, with darkish patches. This got gradually worse, so the stone mason came back to attempt to rectify.

He applied a stain blocker to the affected areas, and then a bit more cream masonry paint. After a few days the blotchiness was back again.

I am at a loss to understand what is going wrong, and what can be done to put the problem right. I would be grateful for any advice you could give. Thank you, Marian

It sounds like your stonemason was a bit too eager to complete the job and didn’t allow the repaired areas to dry-out in depth. Best to leave things be now and let it develop. I suspect the paint will start bubbling and flaking off as the moisture trapped behind it forces itself out. Then leave it for a while to weather before trying to paint again.

How long? I always say a year but people never thank me for saying it.

Thank you very much for your prompt reply and for your advice. Could I ask a follow up question? The blotchy areas of sandstone tend to be where the stonemason merely sanded down the existing stone before painting it (rather than the areas where he repaired missing masonry with new material). Is there a reason why the sanded area would be worst affected? Thank you.

It could be that the original surface was weathered and had become stained over time, which is quite common with sandstone because it is very absorbent. Old sandstone can be almost black on the surface whereas new stone is almost white.

So, when painting over old sandstone, a lot of impurities are going to migrate through the paint surface resulting in a darker finish. Because the sanded down areas are like new stone you wouldn’t get this staining effect and the result, therefore, would be lighter in colour – giving a patchy appearance.

The only problem with this theory now is the use of a stain blocker which I would expect to have solved the problem? I wonder whether a sufficient coating of stain-blocker had been used or if the stain-blocker was water-based and not as effective as required?

I really don’t like using oil or spirit-based stain-blockers on exterior masonry since they prevent any trapped moisture from escaping, but I can’t think of another way around this problem other than just leaving it for a while to weather naturally – which could take a very long time indeed? Removing the new paint and going back to fresh stone is another extreme option but, again, not very practical.

An oil based alkali-resisting primer such as Dulux primer Sealer would be an extreme measure but almost certain to cure any staining problems (cheaper brands are just as good for this purpose, btw).

Maybe try this on a trial area first, just to be sure? You’ll need to let this dry for at least a couple of days before applying a water-based top coat btw.

Painting a wall after removing Ivy Suckers. READ MORE…

I had the problem with ivy suckers stuck to the wall, after a few aborted attempts to get shot of them I used household bleach sprayed on each one. After two weeks they a had all died of and brushed of easily.

My Question I have an old stone wall house which is 264 years old I have painted with masonry paint but after about two to three year I get moss growing through I was thinking of just using a lime based paint which we call whitewash?

I have noticed on old farm buildings which have painted this way for years you never see moss growing. Can you advise? Tom

You tend to get moss growth on North-facing walls where any moisture tends to gather and doesn’t get a chance to dry out. You’ll also see it where there is a leaking gutter or fall pipe.

Bear in mind also, old buildings tend to have a single skin construction of very deep stone and a lot of moisture can be contained within. If the building had been painted with limewash originally this may have helped the natural drying-out process and you may not have such a problem now. This might also explain why you have seen similar buildings without any moss?

However, since the walls are already painted with masonry paint you are not going to get any benefit by overpainting with limewash – not that I would recommend doing this anyway.

You can, however, wash the surface periodically with a fungicidal solution which should help to keep any moss and mould growth at bay.

Persistent efflorescence on rendered wall. READ MORE…

I have a covered terrace with rendered walls. Every very year I have to sand the wall back, due to effervescent salts coming through, and repaint. The strange thing is, it doesn’t happen on the outside wall that faces the elements. Any idea what paint I should use? I was thinking of a lime wash. Thanks, Tony

Normally, you’ll get efflorescence where the walls have been recently rendered and it is a perfectly normal side effect of the drying out process. The best advice in these circumstances is to not paint the wall until the wall has dried in depth and no more salts are coming through.

In your case though it’s possible you have some form of damp problem in the side of the house where this happens, although I would expect some bubbling and flaking of the paint as well?

Since the walls are already painted I don’t think using a different kind of paint is going to help. It may be worth investigating further to see if there is some underlying damp problem though?

Removing weathering with a wire brush. READ MORE…

I intend painting a small plinth on which stands my dad’s headstone and the plinth’s surface is just a plain concrete render.

Would it be advisable to wire brush the render to remove the weathering before applying a couple of coats of exterior masonry paint?

The graveyard is quite exposed so I would appreciate a hint as to the best, water resistant paint. Thank you for any advice in advance. Allan

The problem with using a wire brush is that small particles of metal become embedded into the surface and this leads to rust-staining which is difficult to get rid of. Best use a brush with nylon or natural bristles.

Masonry paint should be fine, if you thin the first coat slightly, but it will get dirty and need re-doing regularly. Dark colours are obviously a better choice for this purpose.

If you want a water-resistant finish you could use an oil-based gloss or eggshell paint. You’ll need to use an alkali-resisting primer and an undercoat first. Although, I think, you’ll likely find the surface will still attract dirt and need regular cleaning?

Exterior masonry paint in a conservation area. READ MORE…

Please could you help me with a question about choice of exterior masonry paint to be used over an existing masonry paint? Our local conservation officer has said we have to use Keim Masonry paint as the building is listed and in a conservation area, and that it allows the front face of the building to breathe.

My question is based on my impression that Keim will be an expensive option and there may be lower cost, but equally as good alternatives from the likes of Sandtex in their exterior paint range and at cheaper prices. Anthony

If you are confident the existing coating is ordinary masonry paint then re-painting with something similar is the best course of action. You could overpaint with Keim but the benefits of doing this are virtually non-existent.

It’s possible the conservation officer is trying to appear more knowledgeable than he actually is.

Painting cottage walls where ivy has been removed. READ MORE…

The outside of our cottage had ivy growing all over it and although we’re removed most of it without bringing off the layer of paint underneath, we’re still left with thousands of tiny “feet” or suckers, each a few millimeters long.

I tried scrubbing and powerwashing too but the little buggers cling on. Is it foolhardy to paint over them with something like Weathershield or will they discolour a white surface? Keith

Ivy tendrils, or suckers, can be a nightmare to get rid of even on smooth surfaces like uPVC. The best way to deal with them is to let nature take its course and they will decay eventually.

Painting over them presents a couple of problems. Firstly, you’ll be sealing them in which retards the natural decaying process you really want to promote. And, secondly, as you rightly assume, it will lead to discoloration of the painted surface.

I have answered another question on this subject before but, alas, this unfortunate person was dealing with a wall that had already been painted.

Painting over Keim painted walls. READ MORE…

Our 15-yr old exterior painting with Keim paint is looking tired and a bit mouldy. Can we repaint with Dulux Weathershield, or would its lesser permeability lead to damp problems? Could we just pressure-wash and maybe also use a fungicide? Tony

You can overpaint with Weathershield and it’s unlikely you’ll experience any adverse effect unless there is already an underlying problem – which doesn’t seem to be the case here. You can, of course, overpaint with Keim mineral paint and lose no permeability at all.

Pressure washing and treating with a fungicide will remove a lot of the mould but whether you can can eradicate all traces of it depends on the severity? Little to lose by trying though since it will be ideal preparation if you do repaint.

What can you paint JUB render with? READ MORE…

Can I use water based masonry paint over marine ply? READ MORE…

Can I use water based masonry paint over marine ply with 2 coats of water based primer/undercoat on it, for exterior use? Brian

You can but bear in mind that masonry paint will absorb a certain level of moisture – so the boards will not be as fully protected as if you used a traditional gloss finish.

It really depends on what you’re using the boards for; if they are going to be upright then not so much a problem than if they were to be laid flat. Also, it is the edges that will absorb more water than anything so, whatever paint you use, always ensure the edges are fully sealed, exposed or not.

Park Home painted with Resitex. READ MORE…

My park home has always been painted using Resitex, however I was talking to the guy who does most of the painting on site & he said once the 10 year warranty runs out you are just as well using Dulux Weathershield in his opinion it does the job just as well & is much cheaper. Phil

Yes, you could use WeatherShield, so long as the surface is clean and free of algae.

Painting over Monocouche render finish. READ MORE…

Help!! I’m becoming very confused!!The house has a Monocouche (Weber product) render finish.

About 12 years old, but due to some cracking, which have been filled, but not a good colour match I’m thinking of a paint job. It would appear that some masonry paints are not recommended for Monocouche. Weber do a paint for this render finish, but it’s horrendously expensive!!

It appears that I should use a breathable paint, but it would seem that not all breathable paints are actually breathable!!

Any advice would be most welcome.PS The house is 1/2 mile back from the South Coast, so get quite a bit of “fresh” air at times! Mike

As a general rule, through coloured renders such as Monocouche and K-Rend can be painted successfully with traditional masonry paints provided that the coating is in reasonable condition. However, if you want to be covered by any warranties then you’ll have to use a system as specified by the product manufacturer.

In regard to your question about some breathable paints not being breathable, I’m afraid I can’t answer that one. Maybe you can refer back to whoever told you this?

Painting a plinth with non-posh paint. READ MORE…

Have just finished an outside paint (Earthborn) on a recently lime rendered cottage. I am satisfied with the result.

However there is a plinth below the drip bead of about 3 to 4 inches which needs to be in black, to match the rest of the cottage.

Earthborn only do a slate colour in 5L (£80) or 100ml (£10) only. I only need a litre to finish the job. Any advice please that will do the “breathing” bit but not at those prices.

Would a litre of Weathershield do any harm? Alex

No harm at all, no. I would consult with the customer first though as they can be a bit funny about you using ‘normal’ paint when they have paid a premium for a ‘posh’ alternative.

If they prefer an eco-type paint a jet black exterior finish is available from Little Greene although it does have a blue/grey tint

Alternatively, Fired Earth have a charcoal finish that’s more of a pure black

Can you use masonry paint on rough timber such as sheds? READ MORE…

You can but, since it hasn’t been formulated for use on rough timber, the results are unpredictable. I would advise using an acrylic water-based primer first though.

A couple of problems you may encounter are migration of stains from preservatives causing unsightly brown patches; and, longer term, constant expansion and contraction of the timer causing the paint film to crack and loose its adhesion.

Of course, neither of these things may happen and everything will be fine. It’s just the risk you take.

Is there a paint which you could suggest which could cover up blemishes in the render? READ MORE…

Is there a paint which you could suggest which could cover up blemishes in the render. Obviously smooth paint does not really mask any imperfection! – Thanks, Farah

It depends how severe the problem is really? You can use a textured masonry paint like Sandtex which helps to hide minor blemishes but if they are very prominent it isn’t going to be much use.

Johnstone’s Jontex is an alternative option; it’s a fair bit thicker than regular masonry paint and you can apply it by roller to give a rough textured finish.

Again though, you are taking a bit of a risk as the end result may still not be satisfactory and you could be wasting your time and money. It may be worth doing a trial area first but, even so, it’s not going to be cheap. A 10 litre pack (the smallest size available) is going to set you back over £60.

Unfortunately, with paint you are always limited with the state of the surface you are presented with and a perfect result isn’t always possible.

Painting covered passageway brickwork walls. READ MORE…

Hi, I’d be very grateful for your help, I have a passage way between my house and garage which as always been covered with a roof, just recently I’ve had doors fitted to both ends so now it’s an indoor space.

The walls are of house brick which I’ve just had plastered with “thistle hardwall plaster” and left in a rough texture finish with no finishing plaster on top. What would be the best paint for this area. Andy

I am assuming you are talking about the interior surface of the wall and the brickwork is a single skin?

If this is the case, I would use something like Crown Covermatt, Johnstones Jonmat Premium or Dulux Supermatt

In other words, an emulsion paint without any vinyl additive that is going o prevent the wall from drying out. You’ll need to thin the first and second coats quite, a bit so it soaks in, and finish with a full third coat to get a decent result.

That’s right I’m referring to the interior surface which as the “thistle hardwall plaster” on it. If I wanted a more durable finish would any of the masonry paints be suitable? READ MORE…

You could use a masonry paint but they are formulated for exterior use, which leads to a couple of disadvantages.
Firstly, because exterior masonry paints also have to shed water, they have a resin content that does still allow a certain amount of moisture to escape but not so much as an interior contract matt that is specifically formulated for this purpose.

Also, the levels of Volatile Organic Chemicals (VOC’s) used in their manufacture is much higher because they are normally going to be used outdoors. The levels are not significant but still worth being aware of, especially since odour levels will be much higher in confined spaces and this may take a while to clear.

Painting over textured masonry paint with small cracks. READ MORE…

I have bought a house which has textured masonry paint, which is thin with many small cracks and some green tinge. i would like to repaint, but don’t know whether it is ok to just paint with sandtex smooth exterior paint or whether I should seal the surface cracks somehow..grateful for any advice. Dave

The green tinge is likely algae growth which needs to be treated with a fungicidal solution before re-painting. The cracks are a bigger problem though since they will allow moisture to penetrate and become trapped behind the rendered surface.

This can lead to a premature failure of the paint surface and, in some cases, lead to internal damp problems. Masonry paints can deal with normal levels of moisture in the wall but not where there is excessive water absorption.

For a few minor, random cracks the course of action is to rake them out with a knife so they are wide enough to be properly filled with a cement compound. Once these repairs are dry you can spot prime with a thinned solution of masonry paint and then proceed to paint the walls as normal.

If the problem is more widespread and there are so many cracks that it isn’t practical to repair them all then you have no choice but to remove and completely replace the existing render.

Simply painting over the cracks isn’t going to work over the medium to long term and you would be wasting your time and money. Beware of any products that claim to offer a solution to this problem also, they are expensive and don’t work.

Through-coloured render with visible climbing plant suckers. READ MORE…

Hi, I’d be very grateful for your help – I’ve bought a house (built in 1850s) with a cream through-coloured render (type unknown) where the previous owner has allowed climbing plants to become overgrown into the roof.

These have been cut back but the render now shows brown aerial root suckers which cannot be removed without damaging the surface.

The suckers are very small and flat and indistinguishable from the texture of the render, so it just the difference in the colour which is the issue.

It is evident from sections elsewhere around the house that the suckers do not lose their grip/deteriorate even after a very long time. l am considering over painting the render – what type of paint should I use or do you have another suggestion please? Sandra

The root suckers will decay eventually, so any fix is only going to be temporary. In doing so, this could lead to staining and a breakdown of the paint surface.

However, this may take some considerable time so you may not have much to lose by painting now and addressing any issues when it comes time to redecorate?

Hard to say what kind of paint has been used but regular masonry paint is the safest bet. If has been done with lime you can easily check if the surface is powdery and absorbs water readily. If it is lime you’ll need to re-do the same.

If it is masonry paint, just use the same again. I would start by painting a few areas, where the roots are, just to see if any problems arise. Most likely is bits of staining which, so long as it’s minor, can be touched up with an oil based paint first to seal and then repainting as normal.

Thanks very much for your reply. The render hasn’t previously been painted as it is through-coloured – would you still suggest a masonry paint?

I’m concerned because I’ve read that painting render which is not designed to be painted can cause problems eg loss of breathability and cause the render itself to fail.

KEIM say their Soldalit-ME paint system offers breathability and “is ideal for decoration of all mineral surfaces, in particular through coloured materials in need of a protective, long-life redecoration”, Is this a worthwhile option?

Without knowing what this ‘through-coloured’ material actually is I would hesitate to recommend a mineral paint system such as Keim.

The advantage of using mineral paints is that they form a chemical bond with the wall rather than just sticking to the surface. But this assumes the render is a regular cement based material and, in your case, there is sufficient doubt for me to suggest caution.

You could contact Keim directly for advise although I’d guess they’d want to do an inspection before recommending a course of action. The matter of the embedded root suckers is a further complication.

Regular masonry paints are moisture vapour permeable and are therefore ‘breathable’ so you need not worry about this being a problem.

The render material is less of an issue since the paint only needs to adhere to the surface and you can test this yourself without incurring any great expense.

This would be my preferred course of action but, by all means, seek further advice.

In what circumstance would I use fine textured white paint over a smooth masonry white paint? READ MORE…

I am painting the Window sills and the door surrounds of my house. In what circumstance would I use fine textured white paint over a smooth masonry white paint? Zahra

It can mask minor imperfections, that is all. Textured masonry paint is sometimes useful for where the walls are uneven or where the new render doesn’t quite match the existing finish.

If your walls are generally OK there isn’t any point using it.

Painting pebble/spar dash walls with a mineral-based masonry paint. READ MORE…

I have a 1922 built detached house that had pebble/spar dash on the outside. Most apperas original, but at least one wall has been re-done in the last 10 years.

The property has cavity walls,, and is near (1/4 mile) the coast in the south of England. I have been looking at silicone (mineral based paints (partly because I spend a lot of time in Germany, and their walls seem to keep cleaner longer than ours!).

However, which paint type would you suggest – I will be looking for a pastel colour? Denis

Ideally I would suggest using a mineral based system although when painting over pebble-dash it is best to get advice directly from the manufacturer.

With standard masonry paint there isn’t much of a problem but, given the significant cost difference, it is safer to deal direct. Then, should any problems arise, they are liable for putting things right (so long as you follow their specification to the letter).

Keim are the market leader and I think you’d be OK with their Granital or Soldalit finishes.

You could, of course, opt for basic masonry paint. Since you have cavity walls and are not directly on the coast you can expect a reasonable life expectancy of any decent brand such as Dulux or Sandtex.

Another mineral based you might be interested in is Earthborn Eco Pro. It’s a 2-part system and, according to them 9 I have no experience with this brand myself) it is suitable for use on pebble-dashed walls. They have a nice pastel colour range too, which is a bonus.

What’s the best masonry paint to use on a Grade 2 listed building? READ MORE…

Hello, I have a grade 2 listed building I have spoken to the people at Beeck who suggested i spray water at the wall and if it ran off then it was likely to be a modern paint rather than a mineral paint. can you suggest the best paint to use i am guessing there is no point using the mineral based option if it is going over a non mineral base. Is that right?

Also the house is on a busy road so i assume i need to clean the walls before i paint do i need a special product to do this?

A basic question i know but do i paint the walls first and then the window frames or vice versa. Also the shop front is all black which i would like to get rid of can you tell me the quickest way of covering the black please. Many thanks, Emma

It is unlikely that a mineral paint has been used before and yes, there is no benefit in applying a mineral based system on top of a standard masonry paint.

It may be worth ruling out the possibility that a lime-wash has been used before though. Lime finishes tend to be rather pale in colour or all white but you can only really be sure if a lime-wash has been used by chemically testing a sample in hydrochloric acid (commonly sold as brick cleaner) to see if dissolves in a ‘fizz’. However, if you spray a sample area with water and the surface absorbs it without any run-off this is a good indication.

Assuming it is just standard paint though, any exterior masonry paint will do although I always advise buying the best quality you can afford.

Cleaning the walls sounds like a good idea but I wouldn’t worry too much about this unless they are very badly affected. It may be worth painting a sample area first though to check that any surface dirt doesn’t migrate through to the surface of the new coating.

If you do need to clean the walls a pressure washer with a solution of water and fungicidal solution should do the job nicely. Ensure the walls have plenty of time to dry out afterwards though as water can easily work it’s way in through hairline cracks and where there are openings (windows and doors) that have not been adequately sealed.

I would generally do the preparation on the window frames first, maybe bringing them up to undercoat level, and then doing the walls. Apply the final coat when the walls are finished.

The quickest way of covering black is to use an extra coat of undercoat, two extra in extreme circumstances. There are some that say using a pale grey or some other colour first makes a difference but it doesn’t.

Can you buy additives to go in the paint to stop moss and algae growing on the render? READ MORE…

You can but they tend not to be very effective over the long-term. Exterior masonry paints already contain an amount of fungicide but there is a limit to how much you can add before it is detrimental to the overall performance of the coating. All paints have a few basic components and each type is formulated as a compromise that gives the best results for the use it is intended.

Owatrol Mould Killer is a product that is a marketed as a solution to your problem but I would be cautious of recommending it.

Fungicidal washes such as Everbuild and Dulux are more suitable as a preparation and for occasional spot solutions for small areas. I wouldn’t expect too much though. Regular maintenance and repainting is the only certain solution.

Rusticated render with plastic inserts, can these be painted with WeatherShield? READ MORE…

My 10 year old, four-storey house has rusticated render on the ground floor level, below a bell cast. The indents of the three horizontal bands forming the ‘rustication’ are lined with plastic inserts. I intend to repaint – same colour – using Dulux Trade Weathershield Smooth Masonry paint.

Will this adhere to the plastic without needing any primer of something like Easy Surface Prep or similar?

Also, being a tall house in an elevated location, I wondered whether it’s worth paying extra for Dulux Maximum Exposure? I’d be grateful for your thoughts. Stephen

The Weathershield may well adhere to the plastic but you can’t be certain. To be safe I would use the ESP first.

The maximum exposure paint is a bit more flexible than the standard version but unless you have experienced problems previously I doubt you’ll see much benefit? Maybe, as a compromise, use it for the most most exposed elevation and use the standard stuff everywhere else?

Lintels and window sills painted with oil-based paint. READ MORE…

I want to paint the window sills of my Edwardian house. Originally the lintels over the window and the sills were all painted with normal oil based paint.

The lintels are pretty much ok only minimal flaking but the sills are badly worn and flaky which I have sanded down as much as I can almost to the original concrete. I understand these will need ‘bonding’ before I repaint.

My question is, do I then use oil based paints( undercoat and gloss) like the lintels, or do I use a Masonry paint like Dulux weathershield? And if so can I use this on the lintels? Tony

It depends what kind of finish you want?

For a traditional gloss finish as before you’ll need to prime areas where stone is exposed with an alkali-resisting primer such as Dulux Primer Sealer and then apply a coat of undercoat followed by one or 2 coats of oil based gloss.

If the exposed areas are minor you could probably get away with using thinned undercoat as a spot primer – but only if it’s the odd patch here and there.

A masonry paint will give a matt finish that will not shed water so easily and will need re-doing more often. Assuming you have rubbed down the existing surface sufficiently an all purpose primer such as Zinsser will provide a suitable bond.

Painting sandstone walls near to the sea, what is the best paint to use? READ MORE…

My house is a Victorian terrace, built in 1840, and has solid sandstone walls. It’s also right by the sea so subject to some pretty nasty weather. The front of the property (which is on the lee side from the sea) has been coated at some time in the past with what looks like a cement render. It’s bossed in many places and water runs between it and the sandstone so I intend to remove it.

Having removed a test area, some comes off easily whereas other parts take a layer of stone off with the render, so I may need to repair some of the blocks. Once I’ve done all of that though, I’d like to paint directly onto the stone. This has been done on neighbouring properties and looks much better than render.

Planning constraints (as well as erosion) prevent me from leaving the stone natural so it has to be painted but I keep getting conflicting advice on which paint to use.

A local painter, who has painted several of the properties around here, says he would only ever use a pliolite paint. from what I understand though, this would trap moisture and damage the stone (this is already evident on many of the properties he’s painted).

Others recommend Dulux Weathershield (trade) as the best product but the local Dulux shop say they do not recommend it for sandstone, and would never recommend painting directly onto sandstone with any product.

Grateful for any advice and recommendations. Gordon

Your local painter is an idiot, pliolite-based paints have one purpose and one purpose only. That is that they are not damaged by sudden rainfall immediately after application. There is no domestic use case at all.

Secondly, people who work in paint shops are not experts and any advice they give can usually be discounted as nonsense.

On a positive note, it sounds like someone you have consulted does have an idea as to what the best paint to use is. That is Dulux Trade Weathershield or, if you want to push the boat out, Dulux Trade Weathershield Maximum Exposure Smooth Masonry Paint

There is a case for using a silica-based painted system that will bond naturally but this is a specialist job and doing it yourself or employing someone with no experience of such systems can end up being more bother than it is worth.

When you have removed the existing coating back to bare stone I suggest you leave it alone for a full year in order to ‘weather’ before attempting any painting so that any loose material and excessive trapped moisture has chance to escape naturally which should reduce the chance of any subsequent problems.

Painting a concrete yard. READ MORE…

My son has a grotty back yard that he wants to spruce up. The ground is just concrete, not paving stones etc. He has seen that some people have simply painted over the ground in their back yards, and he thinks this could be a straightforward and affordable option.

He was thinking of painting the yard grey. Are you able to recommend what sort of paint he would need for this purpose, and what preparation would need to be done?

Thank you very much. Sandra

I imagine his neighbours are using a standard floor paint that is normally used for painting garage floors and such. I would recommend the same but make sure it is water based since this will make the job a lot easier. He’ll need to make sure the floor is as clean and dry as possible.

With a water-based finish he won’t need any special primers, just make sure the first coat is thinned with water just enough so it soaks into the surface but not so thin thin that it is just coloured water. A bit of trial and error on a small test area first is advisable.

Then just apply one or two more un-thinned coats to finish.

Bear in mind that moisture will still be absorbed by the concrete from the ground so, over time, you will get bits flaking off and bubbling. There isn’t anything you can do about this since it depends on the water level underground. A bit of regular maintenance will do the trick though.

Painting a breeze block shed. READ MORE…

Hi I have a large breeze block shed with rain coming through the walls. It hasn’t been painted for years. What do I need to apply as base, first and top coat ? Do I need it to dry out before starting work ? Thanks, Joy

A single skin breezeblock wall is going to difficult to make water-tight but painting might help? Also bear in mind that how the walls are constructed will be a facture as essentials such as a damp proof membrane and proper detailing around openings is often omitted.

Yes, you do need to allow the walls to dry out in depth so it is a project left until the end of summer rather than right now. You don’t need any specialist primers or finishes, ordinary masonry paint with the first coat thinned sufficiently that it soaks into the blocks and provides a key for subsequent coats.

I should re-iterate, this isn’t going to make the walls ‘water-proof’ but it should mitigate the worst of the problem.

If you have a question about painting the exterior of your home, or about masonry paints in general, please get in touch here…

See Also
Painting window frames
Painting Exterior Woodwork
Painting a wall with a roller
Painting Rendered Walls