Painting Exterior Woodwork

The painting and maintenance of external woodwork is a job often neglected or constantly put off, not because it is necessarily an expensive exercise but because it can be time-consuming and often involves working at height, which a lot of people are not comfortable with.

However, it’s one of those aspects of home maintenance where a little time and money spent early on can yield big savings in the long-term.

Where to Start?

It is likely that you’re contemplating repainting the exterior woodwork because the existing coatings are starting to fail or the timber itself is in a state of decay. Failure of finishes to exterior timber and damage to woodwork is usually caused by one or a combination of the following:


Fluctuations in moisture content will cause expansion and contraction in timber, raising of the grain, splitting and distortion. A high moisture content in timber will cause paint films to lose adhesion and fail and will also cause wood to rot.

The end-grain of joinery is most susceptible to the absorption of water and is often the most neglected area. It’s important, therefore, to ensure that end-grains are fully sealed and this includes not just obvious area such at the end of window sills but on internal joints in window reveals as well.

Fungal Attack

If the moisture content in wood remains over 22% for a prolonged period of time then micro-organisms such as fungal spores can germinate and lead to wet rot. It is essential that any new timber is treated with a suitable preservative.

Ultra Violet Radiation

Direct sunlight will cause wood surfaces to deteriorate. Bare timber left exposed to sunlight over a period of time will degrade and reduce its ability to hold a paint surface. Varnishes tend to fail early because they do not filter out the radiation. Dark paint colours will also absorb more radiation and should be avoided in south-facing areas.


Existing paintwork in reasonable condition can be simply rubbed down with a good quality abrasive. Any paintwork which is loose or in bad condition will need to be removed by either scraping or with a heat gun back to a firm edge. It isn’t necessary to remove paint which is in good condition.

Wood which has been weather damaged (usually grey in appearance) will need to be sanded back to a new surface if possible. Treat any bare wood with a suitable preservative and allow to dry before priming

If you need to make good any damaged woodwork always use a two-pack epoxy based filler for medium to large areas. Mix small amounts of filler and build up in two or 3 layers rather than trying to do the job with one lot. Only use ready-mixed fillers for very small areas or for surface imperfections.

Paint Systems

Exterior paints are categorised as solvent-borne (oil based) or water-borne (water based or ‘quick drying’). Oil based systems are generally based on a separate primer/undercoat and finish while water based systems tend to be a coat-on-coat or ‘all in one solution’.

In terms of finish the oil based systems will give a high sheen or glossier finish but in terms of performance the low-sheen water based alternatives can perform better.

In 1984 the Building Research Establishment (BRE) conducted a series of trials to determine the performance of exterior paint systems for external timber. Surprisingly they found that water based paints systems performed significantly better over time than conventional oil based paints and low sheen finishes performed the best.

Even more surprisingly they found that a traditional system of one coat oil based primer with one undercoat and one coat of gloss performed the worst of all.

Paints described as microporous, moisture permeable or breathable claim to allow water trapped within timber to escape as a vapour and so improve the performance of the paint systems. There is, however, little evidence to suggest that ‘breathability’ is the major factor at work. These systems do indeed perform well but mainly because they have been formulated for exterior use with a balance of properties including increased flexibility, adhesion and fungal resistance.

The system you opt for will usually be determined by convenience and/or your budget. Water based paints are generally easier to use and can be re-coated after a few hours. Oil based paints will give a traditional glossy finish but can be time-consuming and require more thorough preparation.

Premium branded paints, such as Dulux Weathershield, especially formulated for exterior use will always perform best but can be costly compared to traditional alternatives. However, it will often be a false economy to try to save money on materials because although the initial result may be comparable it will often mean you have to repaint more often.

Reference and Further Reading

BRE Maintaining paintwork on exterior timber – J Boxall and JA Smith
BRE Digest 422 – Painting Exterior Wood
Architects Journal – Paint, Finishes & Sealants – Brian Keyworth

BS6150: 2006 Painting of Buildings – Code of Practice
BS 5268-5 Structural use of timber – Part 5: Code of practice for the preservative treatment of structural timber
BS EN 927-3 Paints and varnishes – Coating materials and coating systems for exterior wood – Part 3: Natural weathering test


I have several windows in need of exterior redecoration… I have been advised that I should choose my primer according to what topcoat I intend to use… READ MORE…

I have several windows in need of exterior redecoration (to varying extents!). The were previously done with solvent-based gloss. Obviously it’s now too late in the year to tackle the whole job, but I want to put some primer on areas of bare wood to protect it over the winter.

I have been advised (by Dulux) that I should choose my primer according to what topcoat I intend to use.

But I am now wondering, what are the weather constraints about applying primer (in terms of minimum temp or when rain is next due), and is solvent-based or water-based better to use in weather that might turn chilly or wet soon after I apply it? Thank you, Catherine

I would normally agree with choosing a prime according to the final finish but, since there is going to be a considerable time involved between coats, it matters much less. Paint cures and hardens over time so after a couple of months the compatibility issues become irrelevant.

At present, any primer is better than none at all and your easiest solution would be a quick-drying (water-based) primer/undercoat. It dries within an hour and will be unaffected by rain or frost after about 4 hours.

I’ve bought an external hardwood door from a company who state the following…We do not advise the use of any oil, wax or water based (quick drying) treatment on your external door… READ MORE…

I’ve bought an external hardwood door from a company who state the following OILS, WAXES AND WATER BASED TREATMENTS INCLUDING PAINTS FOR EXTERNAL DOORS. We do not advise the use of any oil, wax or water based (quick drying) treatment on your external door.

We feel they do not offer enough protection against the elements and can have a detrimental effect on the way the doors are constructed. They can cause de-lamination and therefore we will not offer any guarantee if they have been finished in this way.

If not oil based or water based, then what? I’ve looked at solvent based, but that term seems to be interchangeable with oil based.

From reviews I’ve seen they have rejected claims where Dulux Weathershield was used. John

It looks like they are using this as a general get-out for any subsequent claims for damage rather than as any sort of useful advise or guidance.

Using a water-based primer on a bare wood door can sometimes cause problems such as swelling/warping and (for non-solid wood doors) delamination but not so with solvent/oil-based finishes.

You don’t say if the door is already treated or primed, and the material composition – this would have a bearing on any further advice I could give you.

I have oak windows and they have a uv lacquer ‘coating’ and where this has broken down we have applied UV Osmo oil. Which is better to adhere to the lightly sanded treated wood – Oil or Water-based…? READ MORE…

I have oak windows and they have a uv lacquer ‘coating’ and where this has broken down we have applied UV Osmo oil. The finish is patchy and we have decided to resand and paint them black instead.

Which is better to adhere to the lightly sanded treated wood – Oil or Water-based and also, some of the windows are south facing and so whatever we use needs to be stable in the sun… hope all this makes sense, any advice welcome !! Thanks, Sally

You will need to ensure that the oil already applied has totally dried and soaked below the surface of the wood.

Normally I would say a water-based primer and finish is best on new wood but the presence of oil residue would make this unadvisable. A regular oil-base wood primer, undercoat and gloss would be best.

As for using black paint, please bear in mind that dark colours absorb UV light much more readily than light colours so this may not be a great idea in this particular instance?

My dulux weathershield black satin quick dry paint is drying patchy on my wooden facia boards of my house. I have applied 3 top coats so far. I used a dulux grey undercoat before applying the top coats…. READ MORE…

It is difficult to get a uniform finish when using water-based paints across large surfaces, especially dark colours.

Try using a foam min-roller to apply the paint followed by gently laying-off with a quality paint brush to remove the stippling-effect. You need to achieve this before the paint starts curing so do short lengths at a time, ensuring you’re always working to a wet edge.

Alas, it is the nature of the paint that you are up against but practice and patience may well pay off.

I painted my external door with dulux black non drip. … I went out and came back to find a footprint mark on the bottom of the external frame. How do I salvage this situation asap? READ MORE…

I painted my external door with dulux black non drip. I painted it with 1 coat yesterday and 2nd coat today. I went out and came back to find a footprint mark on the bottom of the external frame.

I was gutted to say the least. The skin had formed and but has been squished due to the force of weight. How do I salvage this situation asap?

Really appreciate your advice. I can send pictures if you have an email. Thanks a million. Jamal (amateur DIYer). Jamal

Just let the paint harden, rub down and start again. It may take a few weeks to fully cure though so wait a few weeks before attempting this.

Do you paint over putty on external windows and doors? If so do you prime them first? READ MORE…

Paint putties with undercoat and gloss, no need to prime.

I have a tudor style property… The timbers are oak from 100 years ago or more some places major rot. The paint of them now is a smooth gloss finish. Is there a better system to use on it as this system has failed massively? READ MORE…

Hard to say really, without removing the previous coating, fixing rotten areas, etc you are pretty much stuck with what you have. There isn’t a paint in existence that will correct previous mistakes.

My pine windows face north, east and west, and were painted with Dulux Weathershield Fresh Sage about 10 years ago. The paint is starting to fail but can source linseed paint in acceptable colours and quantities..READ MORE…

Thank you for the recommendation of water-based over oil-based paint for exterior woodwork. I have spent a lot of time in Scandinavia and was impressed by the preference for linseed tased paint on the woodwork of their houses.

My pine windows face north, east and west, and were painted with Dulux Weathershield Fresh Sage about 10 years ago.

The paint is starting to fail and splitting on the sills and Boston pane beadings. I am having trouble sourcing a replacement Weathershield paint during lockdown, but can source linseed paint in acceptable colours and quantities.

OK, Devon is not Scandinavia, but what are your thoughts on linseed-based paints for external woodwork, given my supply dilemma. John

You should use products that have been developed for use in the UK. The Scandinavian system you allude to may perform well in certain situations but not others. Hard to say without knowing the exact spec of the product you’re thinking of though.

Could you advise me what preparation, undercoat and topcoat I should use on my exterior cement boards please? READ MORE…

I have a 1970 built detached house, brick ground floor and tiled first floor. At the top of the brickwork is a cement board facia about 3/8 of an inch thick and about 15 inches high, running around the outside of the whole house, about 30 yards total. It came ready coloured in white when the house was first constructed so the cement board looks quite shabby after many years of weathering.

About 10 years ago I painted the cement board with exterior gloss but I have just scrapped it all off quite easily, some in large flakes, so it has never bonded properly to the cement board.

I used this as some neighbours had professional decorators paint theirs at the time and that is what they used. So much for copying professionals eh!

Could you advise me what preparation, undercoat and topcoat I should use on my exterior cement boards please. Dave

Remove as much loose paint as possible and any powdery residue before painting again.

For a traditional gloss finish the correct procedure would be:
1 coat of alkali resisting primer*
1 coat of undercoat
1 coat of gloss

*you may find the surface absorbs the first coat of primer quite readily, if this is the case you’ll have to re-coat until you get a semi-solid finish.

For a water based gloss finish (such as Dulux Weathershield)
1 thinned down coat of undercoat – either weathershield or any quick-dry, water-based undercoat)
1 full coat of above
1 coat of quick drying, water-based gloss

*you may find it difficult to get a good finish with a brush with this system because the paint will be drying as you go. A short pile mini-roller is better.

The following method is very likely what your neighbour’s decorators used though (unless they were very professional)
1 thinned coat of white exterior masonry paint
1 full coat of masonry paint or slightly thinned undercoat
1 coat of gloss

I have newly installed unfinished oak veneered doors which we wanted to paint. They have been primed with water based primer… READ MORE…

I have newly installed unfinished oak veneered doors which we wanted to paint. They have been primed with water based primer.

We did a trial door, which appeared ok so proceeded to prime the remainder of the doors. but now appearing not to do so well, cracking and some delaminating quite badly. Is there any way to recover from this?

An aluminium primer has been suggested, would this work if we lightly sanded down the primed doors and applied the aluminium primer ? Any advise appreciated. Thank you, Jo

I wouldn’t recommend aluminium wood primer, especially over the top of a water-based primer.

I’m not sure what you mean by ‘cracking and delaminating’, is this the wood or the paint you’re talking about? Also, are these doors interior or exterior?

I think this is probably a case where I’m going to be competing with s*** advice from elsewhere so I’m not going to hazard any further comment based on guesswork.

Appreciate your response and completely understand. They are internal doors. Its not the paint that is peeling but the wood is trying to lift up through the veneer. We followed advice to prime in water based but wondering if it was the right thing to do now.

Not all the doors are performing in the same way. Some have grains lifting, as you would expect which can be lightly sanded, some have ‘wood’ pushing out from the behind the veneer which are impossible to rub down, given the veneer is only 0.6mm thick.

I suppose I am concerned how the others that appear ok will react in the long run. And If there is anything I can do with the ones that are still at the primed stage.? READ MORE…

OK Jo, it’s all beginning to make sense now.

It sounds like the paint has reacted with the veneer adhesive, hence the delamination. If the manufacturer has recommended a water-based system then surely they are at fault here?

Raising of the grain is, as you say, to be expected and you can mitigate this by rubbing down – although you would have an easier time just using a regular oil-based primer. This obviously isn’t your fault though.

I wouldn’t go any further until you have spoken to the suppliers since whatever you do now is a risk and may also give the supplier an excuse.

See how you get on and let me know what they say. If need be I will suggest a remedy but I really think it’s something that needs batting back to the supplier?

I have been going backwards and forwards with supplier and they have come to inspect. I have checked with the paint supplier regarding paint system applied and there is no conflict in the paint, which I knew as had previously checked.

So far the manufacturer is not giving me a clear path to go, initially they said to use a water based primer but to trial a door first, which we did and waited to fully dry in between coats.

They have now done about turn and said that there factory uses a solvent based to prime (after we had primed the remaining doors, in water based primer, after our ‘test’ door appeared ok after priming undercoating and top coating).

So am now stuck as to what to do. They don’t seem to be forthcoming in providing a remedy but only to replace the worst of the doors. I had indicated at the point of purchase that the intention was always to paint the doors.

I am nervous as to how to proceed. Some doors appear fine, but the problem seem to occur after the second prime/ undercoat in some doors.

Wondering whether to proceed to 2nd coat with the existing primer/undercoat on the remaining primed doors or perhaps 2nd ‘primer’ with a Zinsser?! again any advise appreciated. READ MORE…

It sounds like the suppliers are not the actual manufacturer and they are making things up as they go along? Everything you have said so far points clearly to liability of the supplier. The doors are not fit for purpose if a water based primer can lead to such problems and the conflicting advice has only made the problem worse.

My advice would be not to try and remedy the situation yourself but to go back to the supplier and ask they replace the doors with similar that ARE fit for purpose or to refund you in full, plus some measure of compensation for the time and materials wasted thus far. I think a fair resolution would be to replace the doors with some others of better quality?

As a general rule, any problems you’re going to encounter will be at the initial priming stage. There isn’t much you can do wrong with any domestic paint that’s going to cause problems beyond that. So, if some doors appear to be OK at this stage you should be OK to carry on, no special paints are going to make any difference.

If you want to draw the suppliers attention this thread please do so. I am happy to name them them and give them an opportunity to explain themselves

I am about to start painting the wood fascias at rear of house, I believe the existing coat was some leftover water based masonry paint. This shouldn’t pose any problems should it? READ MORE…

Any paint system is only as good as the surface you’re applying it to so, in this instance, you would likely be wasting money using a premium paint to cover over an exiting finish which is already poorly adhering.

You have two options:

1) Completely remove the existing finish, rub down and start afresh with primer, undercoat and top-coat/s.
2) Accept the current imperfect system has not done too bad over the years and carry on with the same.

Regarding the plastic guttering, this is difficult since, as you point out, there is a fair degree of daily expansion and contraction that will test just about any paint system you use on it.

Again, if the majority of the gutters are still coated I’d be tempted to just paint over again with masonry paint unless you want to scrape it all off and start again? Of all the paints you could use, masonry paint isn’t actually that bad a choice since water-based paints tend to retain their elasticity for much longer than most solvent based alternatives. This is also relevant to your cladding question, btw.

If I were starting from scratch though, I would apply two coats of Weathershield exterior quick-drying gloss (no primer, or undercoat) since this is both water based and especially formulated for exterior use.

I am researching painting our iroko windows. We purchased them about 20 years ago. They have only ever been stained with Sadolin… READ MORE…

Hello, I am researching painting our iroko windows. We purchased them about 20 years ago. They have only ever been stained with Sadolin, which we have always been happy with. Recently we removed the render from our house and was delighted to find a grey stone cottage underneath. The dark stain does not go well with the stone.

We are thinking about painting, but want to make sure we don’t embark on something we do wrong and end up having to spend more time than we have to constantly re-painting. We will ultimately be using Farrow and Ball exterior eggshell with their exterior undercoat.

At the moment this is my course of action. Lightly sand the stain to get rid of flaky bits and to provide some adhesion.

Am I right in thinking it is not necessary to sand all the way back to bare wood. Apply a water based wood filler for any necessary cracks and holes.

Does a water based filler make sense over stain? Remove any dust. Apply an aluminium based primer.

Again is this necessary over stain, or can I use a water based primer baring in mind I am using Farrow and Ball paint. The windows are predominantly south facing and we are prone to the southwesterly winds and

are a 1000 feet up so do get serious wind and rain. I would be more than delighted to hear back from you. Fiona

  1. Yes, sand back where the existing coating is obviously loose and/flaky but if the coating is sound you only need to sand adequately to provide a ‘key’ for subsequent coats to adhere to.
  2. I wouldn’t use a water-based filler on exterior woodwork. I would use a 2-pack epoxy filler. It’s harder work and, for best results, you’ll need to fill twice to get a good result but it will last longer.
  3. Correct
  4. Don’t use aluminium wood primer where you’re also going to use a water-based finish. The two paints are not compatible. Use a water-based acrylic primer or primer/undercoat – the best quality you can afford.

Where there is exposure to ultra violet radiation it is better to use light colours rather than dark since less radiation will be absorbed.

Also, where there is exposure to adverse weather conditions, it may be necessary to re-paint more often than normal in order to maintain suitable protection.

Is it possible to put an oil based exterior undercoat on linseed oil putty, followed by topcoats of exterior solvent based paint? READ MORE…

Yes but allow the putty to set before painting; it should still be reasonably soft but have developed a hard skin on top. This usually takes about a week or two.

My old sash windows have been ‘re putted. I have both standard white and aluminium primers,which would be the better to use. having primed do I both undercoat and gloss. READ MORE…

Standard white primer should be OK. Yes, 1 undercoat and 1 gloss; 2 of each is ideal though.

What paint/system would you suggest for sun exposed handrails? Whatever paint I put on mine doesn’t seem to last very long. The colour is dark green...READ MORE…

What paint/system would you suggest for sun exposed handrails? Whatever paint I put on mine doesn’t seem to last very long. The colour is dark green.

I think it is the sun that is doing the damage as other bits of handrail that get equally wet and pounded by rain retain their colour and stability.

On the other hand, the sun exposed handrail is made from tanalised timber, whereas the other is 120 years old.

Following a recommendation from a friend I am considering Acrylic Barn paint from Bedec, but he is no expert. Emrys

Dark colours will absorb much more ultra-violet radiation than lighter colours, such as white, and this is often the cause of premature failure. Consider using a lighter colour.

Regular oil-based or water-based finishes should be OK, I’m fairly sure it’s the dark colour that is the problem.

I have garden arbor / double seat which was originally finished in a lightly coloured preservative stain. It has faded a bit now and I would like to paint it in a pastel colour similar to a beach hut…READ MORE…

I have garden arbor / double seat which was originally finished in a lightly coloured preservative stain, probably pressure treated.

It has faded a bit now and I would like to paint it in a pastel colour similar to a beach hut but want a fairly flat, non glossy finish.

Can you advise what product to use please, is an external eggshelll suitable and will it be low sheen? Are there any other suitable products for exterior use with a flat finish? Bill

Opaque woodstain comes in a good selection of colours and may be your best solution; it depends really how badly the original stain has faded and whether it was oil, spirit or water based?

The worst case scenario is the stain bleeding through the new finish. You can’t know if this will happen without doing a test area first. If it bleeds through an oil based finish switch to a water based (quick-dry) alternative and visa versa.

Alternatively, you can get a finish that is more like a traditional eggshell. Sandtex Exterior Satin, for one and johnstones flexible satin. There are plenty of similar products.

Can I use and exterior wood paint/stain over Sadolin treated windows and doors. I am thinking of one of the brighter coloured wood paints/stains. I think I have heard that Sandtex do some? READ MORE…

The opaque stains you are probably thinking about are not suitable for previously treated woodwork since they need to be absorbed into the surface of the wood for best effect.

You can use a water based gloss or satin finish over previously stained woodwork though. For a gloss you’ll need to use an acrylic undercoat first but for satin finishes just two coats will get a decent result.

The previous surface should be thoroughly washed down with a sugar soap solution, rinsed and dried to remove any traces of grease and dirt.

The relevant Sandtex products are :
Rapid Dry Plus Soft Satin Paint, and
Rapid Dry Plus High Gloss Paint with Rapid Dry Plus Primer Undercoat

I have a gate constructed with vertical wooden panels in a wooden frame and it is currently painted with an unknown gloss paint system. My problem is that it absorbs so much moisture in the winter that the vertical panels swell… READ MORE…

I have a car width double gate constructed with vertical wooden panels in a wooden frame and it is currently painted with an unknown gloss paint system.

My problem is that it absorbs so much moisture in the winter that the vertical panels swell and cause the outer frame to bow out and bind hard against the other side of the gate.

Currently in summer there is a 15mm gap between the gates. Is there a paint system that could reduce this winter swelling or do I really need to have the gate reconstructed with expansion gaps between the panels? Ray

It is unlikely to be the fault of the paint system used unless it is in a poor state of upkeep, which doesn’t seem to be the case here.

I wonder if the problem is that moisture is being absorbed via untreated surfaces? For example, are the underside edges of the gates treated at all and, if not, is it possible to remove the gates so you can treat these areas the same as the visible parts?

Another possibility is that the edges of the panels are exposed and are also allowing moisture to penetrate. Of course, some natural movement should be accommodated but, as is often the case, whoever built the gates has not allowed for the fact this exposes the edges when the panels contract during the summer.

Dismantling the gates and rebuilding them after all the edges are treated may be an extreme solution but I don’t see any other way of preventing the problem from reoccurring each year?

I hadn’t considered your 3rd comment so I will have a good look to see if the edges of the panels are exposed now that it is dry and opened up. Unfortunately it has just started raining so I’ll take a look tomorrow…

If that is the case, what paint would you recommend to seal the wood bearing in mind the existing paint is in good condition but I have no idea what it is except it is blue gloss? Would it be better to use a non-microporous paint on dry wood to keep the moisture out?

The likelihood is that the existing paint is a standard oil based wood primer, undercoat and gloss. And this should be sufficient although you could upgrade to Dulux Weathersield as it is a fair bit more flexible over the long term.

The advantage of micro-porous paints, in theory, is that they allow moisture vapour to escape without letting water in so this shouldn’t be an issue. The micro-porous paints, such as Weathershield, have the added advantage of being formulated purely for exterior use so they are worth paying the extra few quid for.

If you have to paint the panels again in-situ try and get as much paint as you can into the gaps. Do these first with a small brush and let the paint dry, then do all the surface with a second coat otherwise you’ll have problems with drips forming from the grooves and spoiling the finished job.

I’ve had a look this morning and you are right, there is some paint in the panel joints but it is patchy and thin. So its going to be a small brush and a tin of Weathershield when the weather settles down! Then I’ll see how it goes over winter before doing anything more drastic. READ MORE…

All the best

I have 70sqm of new, good quality marine ply to paint which is being used externally as the cladding on an extension. We’d like Farrow and Ball French Gray in eggshell as the topcoat… READ MORE…

I have 70sqm of new, good quality marine ply to paint which is being used externally as the cladding on an extension (south facing).

We’d like Farrow and Ball French Gray in eggshell as the topcoat but on pricing it and the appropriate F&B undercoat, I’ve had to sit down because of the cost.

After reading your page, I thought that I could maybe use Dulux Trade Undercoat and Primer instead of the F&B one because both are water-based but apparently this combination actively reject one another ‘like opposing magnets’. I’m totally confused now.

Any advice you can offer? We don’t have to have F&B but we do like that colour and finish. James

Farrow & Ball Exterior Eggshell (assuming this is what you want to use) is water based, so, as long as you use a water-based primer and undercoat you will be fine.

You could go for a separate water based primer and undercoat or, the easier option would be a combination Primer/Undercoat such as Dulux or Armstead Trade (which is a cheaper version of Dulux).

I would give the boards two coats of primer/undercoat, taking special care with the edges because this is where the moisture really gets in. You really need to flood the edges with paint so they are properly sealed.

Then I would finish with your eggshell – at least 2 coats, 3 if you can?

We have moved into a part wood/part brick kit built house from the early 1990s that has large areas of wood cladding in an orange brown stain. We’d like to paint the wood black to look more “barn conversion like” and in keeping with the village… READ MORE…

The problem is going to be the existing stain and the possibility that pigment within will work through to the surface of the new finish.

Knowing whether the stain you have now is water-based or solvent-based is the key; and the only way of finding out is through trial and error. As a general rule, stains that migrate through a water based finish will not do so with a solvent based finish – and visa versa.

The first option is to paint over ‘as is’ with an opaque coloured wood stain such as Dulux Trade Ultimate Opaque. This is solvent based.

The alternative is Dulux Trade Quick Dry Opaque which is water based.

Both options will perform equally well although water based finishes tend to be more expensive but are much easier to use (especially over large areas).

Of course, any other brand will do, there just needs to be both options available. And, obviously, before committing yourself to a major purchase it will be worth your while doing a sample area first – just to be sure.

The other option would be to use a stain blocking primer like aluminium-based wood primer and finish with a conventional paint finish. Although this is an extreme measure that I would avoid if at all possible; opaque wood stains tend to last much longer than conventional paints and are much easier to maintain.

have a front door and surrounding woodwork which is painted in dark wood-stain, I am wanting to repaint with a pale green exterior paint. Do I need to use a primer/undercoat or can I just treat it as a previously painted finish…? READ MORE…

You will need to use a primer to stop the colour from the stain migrating through to the surface. An aluminium wood primer will be most effective but can be difficult to cover. You’ll likely need two coats of undercoat.

Water based acrylic primers are easier to use but you won’t get such a smooth finish.

New windows that have been sprayed in a factory with two pack epoxy paint and now are peeling on the outside but not the inside they are only about 1 month old would you use this product on wood that moves? READ MORE…

It is quite common for joinery products to be factory spray finished, which is usually OK for interior use. As you have found to your cost though, it’s a different matter when it comes to exterior use.

Obviously, in answer to your question, the premature paint failure is likely a combination of inadequate preparation and the use of an inappropriate finish.

I need to paint our timber windows which have georgian bars. The carpenter who made the windows advised me to paint onto the glazing (to ensure a watertight seal between glass and timber) when repainting and then scrape off the excess with a razor blade. Is this right…?

The correct way to do it is to paint slightly over the edge of the timber by a couple of millimetres to create a seal but if you are not a skilled painter it’s hard to do this without making a mess of it.

Your carpenter’s method will achieve a satisfactory result but rather than using a razor blade I suggest using a proper window scraper such as this that uses Stanley knife blades.

So long as you keep the edge of the blade flat against the surface of the glass it won’t cause any scratches and, after a bit of practice, you should be able to get a professional result.

My windows have had various types of paints over the years, the last being Dulux weathershield. If using Sikkens XD, is it enough to just sand to give a key or should I go further? READ MORE…

If the existing coating is in good condition you don’t need to do much else; although a wash down to remove any dirt and grease is always a good idea. You may find it needs two coats of XD to get the best result though.

Any advice for painting over timber which has been “tantalised”. The over painting is for cosmetic and light reflection purposes. READ MORE…

‘Tanalised’ timber is simply wood that’s been pressure treated with a preservative. The main problems you’ll have is that the solvents from the preservative used may react with any subsequent coats of paint. This may mean the paint doesn’t cure properly or it may discolour.

It really depends on how long the timber has been exposed to the elements for. I wouldn’t attempt to paint any wood that has been treated recently but if it has weathered for a reasonable period of time the risk of any problems will be significantly less.

First step would be to try a test area with your primer of choice (a water based quick-drying primer is probably your safest bet) and, if there are no problems, carry on as normal. If you do have problems try a solvent based primer instead.

The most likely outcome is that after priming with a water based paint it will dry OK but you’ll get patches of staining. If this is the case just use an oil based undercoat for your next coat and this should stop the stains migrating any further.

Would you say sikkens xd gloss is more superior to dulux weathershield gloss? READ MORE…


Hi which exterior clear product would you recommend for windows and doors? READ MORE…

You won’t find much choice with clear products other than regular varnish or danish oil because a lack of colouring pigments doesn’t provide adequate protection against ultra-violet radiation.

A light coloured stain is the nearest you’ll get to ‘clear’ and most brands are OK. Sikkens is one of the better choices if you don’t mind paying a premium. If you are certain you want a clear finish ‘OsmoUV Protection’ is a good bet.

I am about to repaint the exterior woodwork on our house…I anticipate needing to do some repair work here and there and wondering what to use to prime these areas…? READ MORE…

I am about to repaint the exterior woodwork on our house (last done 20 years ago with oil bsed paint) using Dulux Trade Weathershield Exterior Flexible Undercoat and Exterior Gloss.

I anticipate needing to do some repair work here and there – grafting in new timber, using wood hardner (Ronseal) and 2 part filler. I’m wondering what to use to prime these areas; the Weathershield Stabilising Primer (clear fluid), Dulux Trade Wood Primer (oil based) or Dulux Trade Quick Dry Primer Undercoat (water based).

I’m inclined to avoid the clear fluid as the other two would help equalise the colour. I would very much appreciate you advice. Richard

For spot-priming small areas the quick-dry primer/undercoat will suffice. For larger areas stick to the weathershield primer since it has been formulated for optimum performance with the exterior paint system. For a first coat over 2 pack filler you could just use the exterior undercoat.

We are about to build summer house it is bare wood we have been recommended to use sickens cetol HSL plus is thus product worthy of its price to tag or is there a Product you could recommend? READ MORE…

Yes, it is worth paying the extra.

Is it correct that previously glossed external woodwork which is sound needs only sanding down before re-glossing and does not require an undercoat? And, when giving two coats of gloss externally, is there a relatively fixed time within which I have to give the second coat to ensure a key with the first coat? READ MORE…

Yes, if the existing coat is sound then a light rub down will be sufficient. Ideally, you should wash-down the surface to remove any grease first though.

When applying a second coat the time for the paint to fully cure will vary depending on the type of paint used and local conditions. As a rule of thumb though, 24 – 48 hours max.

What the best solution to prepare and finish black facia on a south facing aspect exterior?
I understand a water based paint might be the way forward?

You don’t say if this has been painted previously or you are starting from new. So, if repainting an existing facia it’s usually best to stick to what was used before. So if that was oil based undercoat and gloss repeat with the same.

For new work you’d be better off with an opaque stain rather than a paint as they tend to perform much better. Some are indeed water based and work perfectly well.

If you want a traditional gloss finish then Dulux Weathershield exterior primer, undercoat and gloss will serve you well. Compared to standard alternatives the cost is much higher but you save in the long run from increased durability.

A final note on the choice of black as a colour. Particularly for south facing aspects this should be avoided, if at all possible, since dark colours absorb much more ultra-violet radiation than lighter colours which are more reflective.

Thank you for your swift reply & advice, however, yes it had been previously painted with oil based paints, however this was in need of redec as it had mainly started to bubble & flake.

I have now rubbed down, keyed existing paint work and under coated with Dulux primer undercoat X 1 coat, 1 X topcoat Dulux weather shield satin black. I hope this slows the requirement for a redec on this south facing aspect. READ MORE…

All the best

How do you paint external render that is weathered but still intact with exterior masonry paint? Would a stabilizing solution suffice? READ MORE…

Thin the first coat.

Stabilising solution is for crumbly or chalky surfaces, it’s use on normal render would be detrimental as it doesn’t allow trapped moisture to evaporate.

If you have a question about painting your exterior wood that hasn’t been answered above, please get in touch here…

See Also
A terrace of houses all painted a different colour
Masonry Paint
Painting a window ledge with white wood primer
Wood Primers