How to Trim a Window

One of my favorite projects we’ve tackled recently was adding trim to the windows in our dining room. We decided we wanted to take on all of the windows in the house eventually, so today I’m sharing the full DIY process for how to trim a window (it’s so easy!) in the nursery. 

Corey and I live in an area of suburbia where most of the houses don’t have a lot of, um, personality. Like, at all. There are a few gems in our area, but for the most part, our little town didn’t start growing until the 80’s. That means that aside from a couple of (gorgeous and expensive and way out of reach) historic/unique homes, the vast majority of our options are builder-grade tract homes built in the 80’s or later.

As much as we’d love a home with tons of personality, we also really love the challenge of taking a plain, boring house and turning it into something special. That’s why we’re constantly doing things like adding wallpaper, wall treatments like DIY board and batten, and changing up fireplaces. We believe a lot of a home’s personality lies in those little details!

One detail we’ve always wanted to have was window trim. Our windows have always just had plain old drywall all the way around. We knew they could feel a little more special with some trim around them. So, when we tackled the dining room renovation, we decided to try it out. And, holy cow, did it ever make a difference!

The best part was it only took a couple of hours (for all 4 windows!). And, it was incredibly affordable. Why wouldn’t we add DIY window trim on all the windows in the house?!

Our goal is to take on each window as we tackle a space. So, since we’re currently focusing on the nursery and needed to hang some curtains, it was time to get it done.

How To Trim a Window

Step 1: Remove the Old Windowsill

The first step is to remove the old windowsill so you can ensure everything matches. We just used a sharp blade to score all the way around, then used a small pry bar and hammer to peel it right up. If you can, try to keep the entire windowsill intact so that you can use it as a template to cut your new one!

We decided to go for a really minimal (and shallow) windowsill. If you want to keep yours the same, then you can re-use the sill or just cut a new one the same size!

Step 2: Cut + Install New Windowsill

You’ll want the new windowsill to be the first thing you install. We used the old one as a template but, as I mentioned above, cut it a bit shallower so that it didn’t hang over the edge of the drywall much. Corey used the table saw to cut the 1×8 board down. Then, he used the jigsaw to cut out the part that would overhang the window on either side. You’ll note that we cut it wide enough so that the side trim would rest on the sill. This is why re-using your old windowsill may not work – the trim would overhang it and look funny!

Once you’ve got it cut (and you’ve made sure it fits), simply add some construction adhesive to the back, slide it into place, and add a couple of nails for good measure.

Next up, you’ll cut a 1X3 piece for the apron underneath the windowsill. Use a combo of construction adhesives and your handy dandy nail gun to install it. If you don’t have a long enough piece (as you can see, we didn’t) it’s fine to use two. You won’t be able to tell the difference once you caulk and paint!

Step 3: Install Side Pieces

The next step is to cut down some 1X4 boards to the height of your window (go only to the top of the window). Use the same method as before to install them. Optionally, you can also install some boards on the inside of the window box to cover up the drywall. We simply lined our boards up with the edge and then painted the drywall next to the windows to match. It saves some material and doesn’t leave you with a weird area where the two pieces of wood meet. Plus, once it’s all painted you can barely tell the difference!

Step 4: Install Top Piece

Lastly, you’ll want to cut your other 1X8 board to span the top of the window (plus the width of the side boards) and install it! I’ll note here that there are a ton of different ways you could set this up. some people install a small 1X2 piece underneath (or on top of) this board to add some extra depth. Other people use different sizes of wood for a chunkier look. You can really do whatever you want here! We went for a very simple look with no extra flourishes or details. But, there’s tons of inspiration out there for fancy window trim if you want to get creative with it.

Step 5: Caulk and Paint

And finally, the most satisfying part of any woodworking project – the finishing touches! Add caulk and wood filler, let it dry for an hour or so, then paint the whole thing!

This is always the step that makes the biggest difference. Even if you feel like things are looking a little crazy, I can almost guarantee this will fix that!

Once we were finished with the trim, it was time to add our new window treatments. Since we left the windows in our dining room bare, I was really curious how the trim would look when blinds and curtains were added in.

The answer? Fantastic. It looks fantastic.

We hung these curtains from Target and I feel like it really helps the whole thing come together. The curtains play so well with the other patterns in the room, and they’re room darkening which is perfect for a nursery.

I’m so excited about how the nursery is coming together, and I can’t wait to share the full reveal. We’re really down to just a few more details that need to be completed! I’m finally feeling confident that we’ll be able to get this room done before our little boy makes his arrival.

Thank goodness. I was worried for a minute there.