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How to Replace Rotted Wood Around a Window – 11 Simple Steps

By: Author Jeff Campbell

Posted on Last updated:

Categories Home DIY

I love old houses. But older homes with wooden windows often end up rotting. So I wondered how to replace rotted wood around a window.

To replace rotted wood around a window fill any small chips or gaps in the wood with epoxy wood filler. Sand and paint and you’re done. However, for bigger problems, you’ll need to remove the sashes and frames and cut out and replace any large rotted pieces of wood.

Luckily with just a little bit of time & skill, along with a rotted wood repair kit, you can have your wooden windows looking great again in no time!

So let’s learn how to replace rotted wood around a window.

For DIYers, check out my Recommended Tools page (click to see it now on my site). I know my page will save you both time and money, and I only list the best of the best either what I personally own or have used, or the top reviewed items on Amazon.

I also list the best, and oftentimes, that’s NOT the most expensive items too.

Co-authored with Alex Omelchenko, window repair expert over at Apex Window Werks.

how-to-replace-rotted-wood-around-window-rotted-windows-with-shutters-middle-class-dad

But here are the . . . 

11 Easy Steps on How to Replace Rotted Wood Around a Window

1. Discover the size of the problem

Before you can fix the problem, you need to know how big the problem is.

So before we get started learning how to replace rotted wood around a window, scrape away some paint to expose the wood. You can use a screwdriver or a small chisel to scrape away the rot.

If it’s only a small bit of rotted wood, your job is nearly done. Congratulations! You can move on to the next step. But if the damage is severe, you need to proceed to Step 3.

2. Fill the gaps using a rotted wood repair kit

Now that the rot has been cleared out, you can fill up the gaps.

An epoxy wood filler works magic for this purpose. Just mix it up according to the manufacturer’s instructions, jam it into the hole and smooth it out, and then let it dry until it’s cured.

Then you can sand it down and paint over it, and no one will ever know what lurks beneath the surface.

Want the highest-rated rotted wood repair kit available on Amazon Prime?

It’s the Abatron Wood Restoration Kit (click to see the current price on Amazon). It comes with everything you need; Liquid Wood, Wood Epoxy, an Applicator bottle, Putty knife, Measuring cup, and even a Mixing stick.

At 4.5 stars and well over 100 reviews, you know this will do the trick and make how to replace rotted wood around a window a breeze!

3. Prepare to do some carpentry

If you were lucky enough to get away with the easy fix above, your window repair job is nearly done.

On the other hand, if there is more rot than wood, your job is just starting.

Go to your garage or tool shed, and get out your woodworking tools. You’ll need a comfortable workbench, clamps, saws, drill press, wood glue, and plenty of carpentry and joining skill.

Easy enough, right? So, let’s get started.

4. Remove window sashes and frames

If your window sashes need to be repaired, you will have an easier time working on them if you remove them first and take them to your workbench.

Unlike the frame which goes around the outer edge of a window, the sash is the wood that holds the glass in place.

And if it’s the frame that’s the problem, you still need to remove the sashes to get them out of the way. You don’t want to break more things while you’re trying to fix other things, do you?

Then, remove the frame if that’s the thing that needs repairs.

It’s much easier to work at your workbench than to do the repairs in place.

If you need help check out how to remove an old window from the DIY Network.

5. Measure everything & Cut out the rotted sections

In this next how to replace rotted wood around a window step, you will hack everything to bits. That means that you need to measure everything before you start playing wood surgeon.

Spoiler alert: you will eventually need to reconstruct the dodgy sash or frame, so you need to know what dimensions you’re working with.

While you will be making the woodworking equivalent of Frankenstein’s monster, it still needs to fit. So just jot down all the dimensions on a piece of paper. If you find yourself removing lots of little pieces, taking pictures along the way won’t hurt either.

The only way to deal with sections that are beyond saving is to get rid of them. Cut your losses. Really. Just cut it out. Get out your favorite trusty saw, and get to work on that wood. But don’t go too crazy. You’re not the creep in a horror movie.

Keep the cuts neat and straight.

Your best saw for precise cuts in tight places?

A Reciprocating Saw, like the DEWALT DCS380B (click to check the current price on Amazon) is perfect!  And at almost 5 stars on Amazon Prime with almost 400 reviews, you know you’re getting a great saw!

6. Find suitable replacement wood

This may be the hardest step.

Ideally, you need wood that’s fairly similar to the original wood. That will be difficult if the original wood is really old because they don’t make it like they used to. Mother Nature, that is.

All the good, old trees that made the good wood are dead now. Just do your best, okay?

If you’ll be painting over it, it doesn’t matter that much, though.

7. Shape and join replacement wood

Now, with the good wood nicely trimmed, you can proceed to manufacture new sections to insert into the gaps.

If you are an experienced carpenter, you will obviously have the skill to join the old and new sections seamlessly. If not, and it’s a big job, you may need to find a good carpenter in your area to help.

After installing a new frame, make sure that the surrounding area is dry and clean since rotting is usually caused by mold which is growing on wood when the humidity level is too high.

To prevent this you might want to check the relative humidity in your house on a regular basis, also such devices as dehumidifiers might help you to keep mold and rot at bay

8. Prepare the surface for painting

Once the woodwork is done, you can step back and admire your handiwork. Beautiful, isn’t it?

Except that the inlaid sections are pretty obvious. No problem, though, since we’re going to hide it all under a new coat of paint.

So, get out your sandpaper, and sand away until everything is nice and smooth.

Also, another common problem with windows is moisture that gets trapped between double pane windows. If you need help, we also have a great post on How To Do Double Pane Window Fogging Repair (click to read on my site).

9. Paint the wood

Now we get to the fun part; painting.

Actually, all of it is fun if that’s your kind of thing. Here you have an opportunity to prevent future rotting by choosing an appropriate paint. Choose durable paint made for outdoor use.

This will ensure that it stands up to weather abuse for many years to come. For exterior avoid using oil-based paints that can lead to mildew and yellow over time.

10. Replace the sashes

Speaking of weather damage, without windows the weather will damage the inside of your house unless you keep it out.

So obviously you need to reinstall your windows.

This is also a good opportunity to do some maintenance on your sashes to keep them gliding smoothly, remove rattles, and make sure they stay up.

11. Remember the maintenance

At long last, your windows are beautiful again.

And since learning how to replace rotted wood around a window was such hard work, you probably don’t want to do it again too soon. Unless you want to turn your skills into an extra weekend job, of course.

If not, just remember to keep up the maintenance. Inspect your windows every season, and do paint touch-ups before it’s too late. That little bit of effort will prevent a whole lot of effort — and money — later.

If you’re a DIY fan, why not check out some of the other great home repair posts on this site such as How to Build a Deck Step by Step (click to read it on my site).

Final Thoughts

In this post, we took an in-depth look into the world of wooden windows.

We looked at the how, why, and when wooden windows need minor repair and full-on major repair. Sometimes windows just have to be replaced. But that’s a HUGE expense.

But for the average DIY person, there are some options beyond paying thousands to replace windows or hire a pro.

Thus, we explored how to repair a rotted window frame. Then we walked you through step by step on everything you need to know about how to replace rotted wood around a window.

That way, you can not only learn a new skill, but you’re adding value and beauty to your home, saving your pocketbook (and utilities and comfort) in the process.

For DIYers, check out my Recommended Tools page (click to see it now on my site). I know my page will save you both time and money, and I only list the best of the best either what I personally own or have used, or the top reviewed items on Amazon.

About the co-author of this post.

Alex works for Apex Window Werks, a home and commercial window and door repair company. AWW offers the following services, wooden window repair, and replacement, broken glass repair, window defogging and more.

The company currently services New York, Illinois, and Ohio. To see if Apex repairs windows near you, check our service areas. Estimates provided at no cost, feel free to get in touch today.

Of course, because of the society we live in, I have to add the disclaimer that by allowing this post, I am not necessarily endorsing the steps outlined in the post nor do I offer any guarantees of the suggested work. The opinions expressed belong solely to Alex and Apex Window Werks. If you have questions, feel free to comment and I’ll do my best to answer, but you may also wish to contact Alex directly at alex@apexwindowwerks.com.

Middle Class Dad is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. As an Amazon Associate, I may earn a small commission from qualifying purchases if you click to Amazon from my site and choose to make a purchase. This is no way increases the cost to you.

Jeff Campbell
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