How to Paint Exterior wood, A complete guide

Richard Quinton

Looking after the outside of your property can sometimes be a challenge. What to do first and which bits to fix and how.

One of the areas that need attention is the exterior woodwork, but looking after it doesn’t have to be a challenge. following a few simple steps will mean your exterior doors and windows will look great and last a lifetime, here’s my guide on how to paint exterior wood.

To paint exterior woodwork first inspect the condition of the wood, remove locks, handles & hinges, strip old paint, sand the surface, fill gaps & holes, treat knots, rub down filler, clean the surface, apply primer, undercoat, & 2 topcoats, sanding between coats, allow to dry & refit hinges & handles.

If you follow these steps your exterior woodwork will look great and be protected against the harshest of weather conditions, read the full in-depth step by step guide below for more details and great ways to save time and avoid mistakes when painting exterior woodwork.

Inspect the Condition of the wood

Inspecting the door or window and frame is the first step in the process and reviewing it so see how much work is required and what needs to be repaired. Look for signs of water damage and rotting.

Pay particular attention to the bottom of the door where water may gather and cause issues.

Check any door seals and caulking around the frame and the wall, as this will dry out and shrink over time leading to water ingress behind the door frame.

You will need to check the door for signs of damage or rot, and plan to remove any decayed areas cutting it back to good solid wood.

You can tell where wood is starting to decay as the surface will be soft and spongy and the paint will probably be flaking away.

If the door is rotting at the outer edges and the frame is no good it may be more cost-effective to replace the entire door than try to repair it.

Check the locks, hinges, and fixings are all in good condition if not and they have become worn or corroded consider replacing them with new Stainless steel or corrosion-resistant units

You may also choose to upgrade door locks to improve security as well.

Remove door furniture & screws

To remove the door from the frame, open the door to allow access to the hinges and their fixings, most exterior doors will have at least 3 sets of hinges to support their weight.

Support the open door using a block or door lifter to avoid it dropping when the hinges are removed.

Unscrew all the fixings except one from all of the hinges, I tend to leave one of the center screws in each hinge.

Older doors tend to use flat head screws whereas modern units will more likely be posi-drive or Phillips screws to hold it in place; always check you have the right screwdrivers ready before you start.

When I remove doors and fixings I keep my tool kit close by as you never know what you might need, especially like using Wera hand tools for this type of job as they are really comfortable to use and grip and give loads of torque to remove old screws.

Collect all the fixings in a small container. I tend to use my favorite tool, an old ice cream tub to keep these things in.

Prepare a clear work space to place the door on, I use an old folding work table, but any flat surface will do you can even work on the floor so long as it is clean and dry,

I recommend working from a table or bench that means you don’t have to bend down or reach too far. This will save you from backache in the long run and make working on the exterior door much easier.

Holding the door securely and supported underneath, remove the last of the screws, I leave the middle hinge until last as this is usually at waist height and means you are not holding the door and trying to either reach up or bend down.

Removing a door can be done single-handed but it is much easier to ask for help, having someone hold the door wild you remove the screws make it quicker and a bit safer.

Place the door on the workspace making sure you have room to work on all sides

Remove any hardware from the door including the hinges, door locks, and handles, if you are able, take a few pictures or each one to remind you how to replace them.

Place all the parts into the container for safekeeping.

Strip off and remove the old paint

If the exterior door has not been refurbished for a while and the existing paint is flaking badly, I recommend stripping all the old paint off and taking the surface back to the bare wood.

However the paint is in reasonable condition this may not be necessary, and giving the surface a good rub down will be fine.

There are several ways to strip paint and it can be down to personal preference as to which method you choose.

If you are removing or sanding old paint from exterior wooden doors, always wear a face mask and eye protection, some older paints use lead as a major ingredient, and breathing this in is not good for you.

Using a belt sander to strip back the old paint can work very well, especially on flat areas, I suggest starting with a low grit or coarse sandpaper 60 or 80 grit works well.

This method is simple but can take time and doesn’t work very well on intricate doors with lots of small surfaces or details. Using a sander also creates a lot of dust and mess

Paint stripper, there are several brands of paint stripper which will lift old paint from wood and other surfaces,

Nitro Mors for example is a thick clear paste that you apply to the surface of the old paint with a brush or roller.

As a chemical, it reacts to lift the paint and makes removing it much easier, typically paint stripper is applied and left to work for 30 -40 minutes and then removed using a scraper and cloth.

When working with a paint stripper to remove old paint from exterior wooden doors or any other surface, always wear gloves as it will burn your skin, and work outside or in a very well ventilated area as the fumes can be very strong.

Any chemicals that you keep like paint strippers must be stored safely, make sure they are kept out of the reach of children, and always read the instructions on how and where to store them when not in use.

Always read the manufacturer’s instructions and follow safe working guidelines to avoid any issues.

Using a Heat gun to remove the old paint is my preferred method because it is quick and works on most types of paint, also the heat gun is always available, unlike using a chemical paint stripper which I tend to run out of regularly.

I always wear a face mask and work outside whenever possible when using a heat gun to strip old paint.

It’s a good idea to use gloves as well to avoid burning yourself as the heat gun and scraper will get very hot.

With a good paint scraper in one hand and the heat gun in the other, apply heat to the surface you want to strip and allow it to start to bubble but not discolor, you want to avoid burning the paint.

Using the paint scraper remove the now hot paint from the surface, as you scrape heat the door with the heat gun working along the surface.

It can take a bit of practice to get the paint to the right temperature but once mastered this I find this method to be the quickest for removing old paint.

Rough Sand the surface

With the old paint removed the wooden surface will need to be sanded down to give the primer a good key to bond to.

Sanding is a boring job that can take time but doing it properly will ensure your paint finish looks great and will last for a long time, if you skip on the surface preparation the new paint will not last and in very little time you will be doing the job all over again.

Start with a coarse grit paper, and use as many power tools as you need to get through this stage quickly. For a large flat surface like a standard door, I use a ½ sheet orbital sander and P60 or P80 grit sanding pads.

Once the majority of the old paint and primer has been removed and sanded down, switch to P120 grit sanding pad, this will give the surface a smooth look but create a good key for the new primer to bond to.

Fill the gaps & holes

With the fresh bare wood exposed you should be able to see exactly where any damaged or rotten areas are.

Mark around the rotten wood and cut it out using a jigsaw so that you have good solid wood to work with.

Depending on the construction of the door you may need to remove panels or just cut out some slats.

If the damage is too bad or is eating away at the frame of the door, it might be worth replacing the door rather than spend time and money on a repair.

Once the damaged wood has been removed, replace these areas with new solid wood.

Use a good quality exterior wood filler to close any gaps or small areas of damage, I try to clean off excess filler as much as possible whilst it’s still wet as this saves time sanding later.

Treat the knots

One step that I have to remember is to treat any knots before applying primer. Knots are the circular areas in the wood where a branch has been cut through so that you can see the end grain.

If they are not treated the knots can weep sap and resin and this will lift any paint you apply to these areas, this is particularly a problem with pinewood where Knots are common.

Use a knotting compound or knotting solution to seal any knots in the wood, knotting is a brown liquid made from Shellac which comes from female lac beetles.

The knotting solution or compound is usually applied to wood with a small brush. This then left to dry out completely before applying the first coat of primer.

Rub-down the filler

With the first pass of filler applied the exterior door needs to be left to dry for at least 6 hours, this will give the wood filler time to harden enough so that it can be sanded smooth.

Use a medium grit sandpaper P120 min and remove any high spots or lumps and blend the filler to match the surrounding area so that it is smooth and there are no discernible edges.

I use my fingertips to check for cracks or edges. Gently run your fingers over the area to feel for high spots, you can also use a straight edge to check low spots.

Check out our post on more great tips and ideas for painting and decoration use the link below:

Tips for painting and decorating

Once you have rubbed down any filled areas check for cracks or low spots and apply more filler wherever necessary until the door is repaired to your liking.

Repeat the filling and rubbing down until you are happy that the surface is flat and smooth enough.

Clean the surface

With the exterior wooden surface sanded and prepared, clean off any dust or debris to avoid issues when applying the paint,

I tend to use two passes for this, firstly I vacuum to clean the whole area with a soft brush attachment, paying attention to corners where dust can build-up

I then wipe over the door with a damp cloth and leave the surface to dry. Using a sponge works well, make sure to clean it thoroughly with fresh water.

Apply the Primer

With all the base prep work done now is the time to apply the first layer of paint. For bare wooden surfaces to work bond well to paint they need to be treated with primer first

The wood primer will seal the grain of the exposed wood and prevent the undercoat and top cost from being absorbed by the open grain.

Use a primer paint that is either white or will match your topcoat color. White Primer paint is the most common and cheapest, I use it as it gives a good base to work form with any color.

There are several methods of applying paint. The most common ones used for DIY projects like painting an exterior wooden door are hand brushing, Roller or spray system.

Using a brush is simple and cheap and on small or single projects like painting exterior woodwork would be my first choice.

There is a technique to using a brush that comes with a little bit of practice and it isn’t as fast as using a roller or spraying,

Rollers work well on large flat surfaces, so if the woodwork you are painting is not intricate this can be a good method to use.

Painting with rollers doesn’t give as thick a layer of paint as using a brush and you will still need to use a brush to cover small corners and joints

Spray systems are great for smooth even finishes on multiple smaller pieces or large areas that can be easily masked off.

Using spray systems is quick for applying paint however set up and masking can take just as much time as the other methods, so if you have lots of things to paint setting up a dedicated space can save time,

All three methods have their benefits and drawbacks and you can read more about each one in our post about painting.

When painting at the edges or corners make sure that the paint is applied well but not so much that it will drip or run.

With your preferred method of painting selected and the primer paint applied evenly over the surface covering all the bare wood, it needs to dry off before the next stage

Rub-down the primer

Once the primer has dried off for at least 4 hours and has hardened off, it will need a light rub down.

Using a medium grit sandpaper minimum of P120 rub over the entire surface to remove any high spots, dust, drips, or runs.

Don’t rub the primer paint too hard as this will remove too much of the paint layer and expose the wood underneath.

For this reason, I tend to do this light rubbing down by hand and not with a sander.

Treat corners and sharp edges with care as there will be less paint on these areas.

Once you have rubbed the surface down, it will need a good clean to remove any loose dust, first use a vacuum cleaner and then wipe down with a clean damp cloth.

Let this dry off for a few minutes before moving on to the next step.

Apply the undercoat

The next step is to apply the undercoat, this layer will form the base for the topcoat and provide stability to the painted surface.

Many paint manufacturers combine the primer and undercoat in one paint and you can use this for both the primer coat and undercoat layers.

Using the same technique as for the primer coat, apply an even coat of paint to the surface, I find that working logically in a grid pattern means that I don’t miss out on any spots or paint over the same area twice.

You can use the paint tin or a screwdriver to mark where you have painted as a guide and move it along each time you finish a section.

With the undercoat paint applied leave the door to dry off for 6 hours until it is hard enough to rub down.

For a really well-protected exterior finish or in areas of harsh weather applying a second undercoat will give the wood a thicker layer of protection and the painted surface will last longer

Rub-down between coats

Once the undercoat paint layer has had time to dry off it will need to be rubbed down. This is a dull and tedious process but a necessary one, missing this out or not paying attention will mean you end up with a poor paint finish.

Depending on your preference and needs, rubbing down the undercoat can be done at the same grit as the primer or use a finer higher grit P180.

I rub down between coat by hand as using an electric sander can be too harsh and remove more paint than is necessary, to make things quicker you can use large sanding pads to cover a big area and shaped blocks to get into difficult areas or corners.

Using a higher grit sandpaper will produce a smoother finish, here is a list showing some of the grit levels and their uses:

Class of sandpaper	Description	CAMI Grit	FEPA Grit
Very Fine	Very Fine grit for finishing tasks, Sanding bare wood, and cleaning before final topcoat	220	P220
Fine	Fine grit size Cannot remove varnish or paint on wood but used for preparing for finishes, cleaning plaster, and removing stains from wood	100 or 120	P100, P120
Medium	Leaves a medium to coarse surface texture after sanding for preparing bare wood, removing paint and varnish	80	P60, or P80
Coarse	Has the ability to remove material rapidly, quickly remove paint or varnish	40, 50 or 60	P40 or P50
Extra Coarse	Speeds up the removal of most materials, for heavy-duty jobs like hardwood floor sanding or removing old paint	24, 30 or 36	P30, P36, P16 or P12

There are several more types of sandpaper and you can find out which ones to use for really high gloss finishes and polishing in this post.

Apply the 1st top coat

As with the primer coat once the undercoat has been lightly sanded with the required grit sandpaper and the surface of the wooden door will need to be cleaned and wiped down to remove any dust.

With the base layers applied and prepared the first layer of the topcoat can be applied. Ensure this layer of paint is worked into corners and covers the surface evenly.

There are lots of manufactures that produce exterior paint in all sorts of colors and final finishes such as gloss, semi-gloss, satin, and matt, which finish you choose is up to you but here are a few things to consider when buying exterior paint:

The volume required to cover the surface area, tins of paint come in different sizes (Litres or gallons), and buying larger quantities can save money but try not to purchase too much otherwise it will need to be stored and paint will eventually dry out and need to be thrown away,

Consider which method of application you intend to use, brush, roller, or paint spray system, some paints will need to be thinned down if using a spray system.

Colour Dark colors may need more than 2 coats to get a good even color over a large area. Try to use light colors on south-facing or resinous wood

The finish I prefer Gloss or Satin as they have a wider range of colors and have a long working life are easy to clean or wipe down if they are dirty or marked.

Durability look for paint with a long guarantee there are several with 6-10 year lifetime etc this will help your exterior paintwork last for a long time without the need to be repainted.

Use water-based paint to avoid yellowing or discoloration. This really affects white or light colors.

Final Rub-down

You will be glad to hear that this is the final time the exterior door will need to be rubbed down Woo hoo!! This is the final stretch, and paying particular attention to surface preparation is vital.

Using a fine or very fine sandpaper gently rub over the surface to remove any dirt, dust, drips, or runs.

Don’t rub too hard or stay in one area for long as this will remove too much of the paint layer

Once you are happy that the surface is ready for final paint, give it a good clean to remove any dust or debris, use a vacuum cleaner and a clean damp cloth.

Apply the 2 and final top coat

With surfaces prepared for the final time, the second topcoat can be applied. This will give the surface its outer layer and protection from the elements.

Work methodically across the surface to ensure that complete and full coverage with no gaps or missed areas occurs.

Check periodically for any dust, dirt, or hairs that may have dropped on to the surface as you are working, remove them carefully before the surface becomes too dry, and touch up any imperfections locally.

Once the final top coat of paint has been applied to the surface of the exterior wooden door, allow it to dry fully before moving it and avoid touching as much as possible. I normally wait for at least 24 hours before returning to the freshly painted door.

In colder weather the drying process will slow down and take longer, you can test the surface of the paint by gently applying pressure to an area that will be hidden once the door is fitted.

This way if the paint is still too soft and you disturb the surface it will be less visible once the door is refitted, Usually check by pressing my finger gently against the top edge of the door.

Refit the door furniture

Once the topcoat of paint is fully dry, the door furniture can be refitted. Use a sharp knife to clean out any corners that have additional paint.

Areas such as the hinge or lock recesses can need a little attention to make sure they fit back in place correctly.

At this stage I look at replacing the screws, I discard any fixings that are worn or the heads are damaged, using posi-drive, Phillips, or crosshead screws means a powered screwdriver can be used to replace the fixings

Make sure if using a combi drill or powered driver to refit the door furniture that the torque settings are low so as not to strip out the threads.

Re-hang the door

Once both the exterior door and the door frame have been painted and the door furniture fitted the freshly painted door can be re-hung on the door frame.

I prefer to fit the hinges to the door first and then offer the door up to the frame, this makes aligning the door easier but either way can work.

Use a block to support the door at the right level, you can make or buy door lifters which will make aligning the door hinges easier if you are working on your own.

Put a single screw into each hinge, I find it best to use the center holes and not to tighten them until all the screws are located.

Then once you have at least 3 screws in you can let go of the door and fit the rest, working from top to bottom.

Check the door lock and lock-keep aligned correctly and adjust as required so that the lock operates smoothly and engages fully and you keep the door secure.

Check the door works by opening and closing it a few times, look for any tight spots around the door between the edge of the door and the frame.

For more great ideas and tips on caring for items you use around your home check out our post of restoring Garden furniture just follow the link below:

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This article was written by: Richard Quinton – The DIY Help Desk Owner, Engineer & technical specialist.

Richard is one of the key partners in The DIY Help Desk team. He is a qualified Engineer, writer, and publisher, educated to Master’s level. He is a keen advocate of DIY and home improvements.

Richard enjoys helping others to learn new skills and reach their goals and believes that passing his knowledge and experience on through his writing is an effective way to positively impact the lifestyles and well-being of others on a larger scale.