How to Paint Wooden Window Exteriors

Name one of the simplest and cheapest ways of increasing your home’s curb appeal. Yep – you guessed it – it’s painting the exterior window sills and frames.

A new coat of paint on your wooden window sill exteriors instantly spruces up the look of your house and has the added benefit of protecting these exposed surfaces from damage and rot.

The entire process is fairly straightforward and low-cost, so nearly anyone can do it with a little time and effort. When done properly, the paint job will last for years to come, so you won’t need to repeat the process anytime soon.

I’ll break down each step you need to know to paint your exterior window sills, including tools and supplies needed, and tips for getting a professional-looking finish.

Painting Wooden Window Exteriors: Tools and Supplies



Putting a fresh coat of paint on wooden window exteriors only requires a few basic tools and materials.

How to prepare exterior window sills for painting?

Like most paint jobs, the key to a job well done is in the prep work. A properly prepped surface will cause the paint to adhere better, and withstand wear and tear for years to come.


The first step is to give the exterior windows a good wash and clean. This is especially important if they’re older windows that haven’t been cleaned in some time.

A clean surface free from dirt and grime will help paint to adhere to a surface far better, and will also result in a better-looking finish.

Give the entire window exterior – including the frame, sills, and window itself a thorough wash with mild soap and water and then wipe down with a clean dry cloth.

If your painting the entire house, then now would be a good time to clean the entire house’s exterior.

Remove Old Paint

Next, you’ll want to remove old chipped and flaking paint from the window trim.

scraping old paint with putty knifeUse a putty knife to scrape away old paint from any areas where it’s loose and cracking. Make sure to set up a drop cloth, tarp, or plastic garbage bag below the window to collect any fallen paint chips.

You’ll probably find that the window sill and trim near the bottom of the window are the most damaged and weathered. This is due to the way rain, snow, and the sun to hit the bottom of the window more than the sides and top.

If you run into rot during this process, then you’ll need to repair the rotted wood trim before it spreads further. 

As you’re scraping away the old paint, take the opportunity to examine the state of the caulking between the window sill and the trim. If it’s coming loose, broken, or has visible gaps in it, then you’ll want to remove it with a scraper or putty knife.

There’s no need to remove all of the old paint, just the cracking and loose paint that comes free when you scrape it with your putty knife.

When you’ve finished scraping, use an old brush to sweep away any small paint chips that have collected in the window’s corners.


The next step is sanding the entire surface of the exterior trim. Sanding works by abrading the surface, causing paint and primer applied later to adhere better.

sanding exterior of wood window

If the windows have been painted before, then this step is especially important. It will help ensure the new paint sticks to the remaining old paint.

I like to use medium-grit sandpaper (100 to 150) for this task. This will give the paint enough to grip onto, while not making it too rough or too smooth for the job.

Make sure to sand the entire exterior trim well. You want to create as flat a surface as possible for the paint/primer you apply later on. This will result in better adhesion, as well as a better-looking finish.

As you chip away paint and sand the window surfaces you may expose small gaps or nail holes in the wood. Fill these with a little wood filler, let the filler dry, and then sand flush with the rest of the window trim.

When you’re done sanding, you’ll want to brush away any particles and wipe down the window trim surfaces.

window trim sanded and prepped for painting
Window trim scraped, sanded, cleaned, and prepped for painting.

Then, you’ll want to wash any exposed wood surfaces with mildew resistant cleaner. This will help kill any mold and mildew and prevent it from developing in the future.

Apply Primer

Applying primer isn’t strictly necessary, but in my experience, it’s worth the extra effort.

painting primer on window trim

If you’re painting the windows for the first time, or you’ve removed a large amount of old paint, then you’ll definitely want to apply primer. On the other hand, if the window exterior paint is still in decent condition, then you can skip this step.

Primer works sort of like glue. It will help paint adhere to both bare wood and the remaining old paint, while also fighting against cracking and blistering paint down the line.

Apply primer to the entire window trim exterior, and make sure to keep a damp cloth handy to wipe away any primer you get on the window glass or siding of your house.

Most primers will dry completely in an hour or so, so you’ll likely be able to apply primer and paint in the same sitting. If you’re a little sloppy when painting, then you’ll want to use painters tape during this step, otherwise, you should be able to make do without it.


Alright, now that you’ve cleaned, scraped, sanded, and primed, it’s finally time to do what you came here for – paint your wooden window exteriors!

Painting window exteriors is delicate work, so you’ll want to be a little careful when painting. Keep a damp rag handy to wipe away any paint you get in the wrong spots. You can also use a razor blade to scrape this away later, but in my experience, it’s easier to just wipe it away before it has the chance to dry.

I’ve found an angled paintbrush is far better for painting trim than a flat one. The angled brush makes it easier to get paint into the corners of the window trim, and paint straight lines along both horizontal and vertical surfaces. 2 to 2 ½ inches is a good size for most window trim.

A word about paint:
Exterior paint for wooden windows should be glossy or semi-gloss oil or latex paint. Glossy paint repels dirt and provides a more durable weather-resistant shield against the elements than a flat finish. Look for a high-quality exterior paint that’s mildew resistant. If you’re not using primer, consider paint and primer in one.

Paint all window trim surfaces using long straight brushstrokes. If possible, paint the horizontal surfaces before you paint vertical ones. This will result in clean lines with minimal paint running against the wood grain.

painting window trim exteriorLike with the primer, you can use painters tape to avoid getting paint where it doesn’t belong. If you have a steady hand, you can leave this out and just paint it freehand.

Try to avoid getting paint in any tracks or moving components of the window. These can cause your windows to jam or become difficult to open and shut.

If you’re painting the window trim in two different colors, it’s easier to paint the interior color before the color around the edge of the frame.

If you’re changing the trim to a new color, you may need multiple coats to get the color to look right. Make sure to let the paint dry completely before applying a second coat.


When the paint has dried completely, you’ll want to do a little final cleanup to make sure the windows look as nice as possible.

When you’re painting windows, it’s pretty much inevitable that you’ll get a little paint on the window pane itself. Luckily, this is pretty easy to fix. A simple razor blade works perfectly for removing this excess paint.

Run the razor blade edge under the paint, and then slide the entire edge of the blade between the paint and the window glass. Scrape as much of the paint off as possible, and then wipe clean with a rag.

When you’re finished, wipe down the entire exterior window trim with a damp cloth and voila! You’ve got yourself some brand spanking new looking wooden window exteriors!

Hopefully, you now have a better idea of how to paint your wooden window exteriors. This project will instantly boost the look of your home, and is easy enough for nearly anyone!

Denis Gardner

I've loved tinkering and fixing things for as long as I can remember. So, naturally, I gravitated towards DIY and home improvement when I bought my first home. Nowadays you can find me writing about my passions or messing around with my newest tool!

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