DIY Window Casing

September 30, 2014

Hello Designer Trapped in a Lawyer's Body readers! My name is Sarah and I blog over at Little Red Brick House. I'm so incredibly excited to be sharing my easy DIY window casing tutorial with you today! Thank you so much for having me, Tasha!

I am in love with the Craftsman style of homes. From the columns to the beautiful but simple trim work, I love it all. I'm in the process of adding character to my builder grade home and one of the places that needs character the most is the windows. I feel like windows should have something to frame out all of those beautiful views, much like a picture frame. Being the do-it-yourself type that I am, I decided to tackle this project myself (with a little help from the hubby). ;)

DIY Window Casing Tutorial:

DIY Window Casing | Little Red Brick House

First, my husband removed the old window sill and apron from the window. He scored the seams where the board was caulked to the wall and then popped the sill off using a large rubber mallet. We decided to open the window for this part because we weren't sure if all of the pressure from banging around would break it. Better safe than sorry!

DIY Window Casing | Little Red Brick House

Next, I measured my window and figured out all of the framing dimensions that I would need and then cut the boards with my miter saw. You can see the size of lumber that I chose in the picture below. Feel free to make your boards thicker if you'd like.

DIY Window Casing | Little Red Brick House

Now it's time to attach the sill. We used a jig saw to cut out the part where the sill wraps around the corner of the wall. We shimmied the board in place and then nailed it in.

DIY Window Casing | Little Red Brick House

Next up is the apron. That's the part that sits below the sill.

DIY Window Casing | Little Red Brick House

Then we attached the side casings with our nailer. You will want to make sure you get this part level and lined up with the corner of the wall. Don't worry if there is a gap, you can fill it in with caulk later.

DIY Window Casing | Little Red Brick House

The top of the casing was constructed of a 1×4 board sandwiched between two sideways 1×2 boards. We nailed the 1×4 into the wall but the bottom 1×2 was nailed into the side casings and the top 1×2 was nailed into the top of the 1×4.

DIY Window Casing | Little Red Brick House

Once your frame is in place it's time to bust out the wood filler for the nail holes. Fill your holes and any knots in the wood. Let the filler dry and then sand everything smooth. Vacuum any sanding dust and wipe everything down with a damp rag.

DIY Window Casing | Little Red Brick House

Now it's time to caulk all of your seams and prime. You can use a caulking tool or wet your finger and run it through to smooth out the caulk. I prefered using my finger. The trick to caulking is to make sure everything stays damp (not dripping wet). I like to have a glass of water to dip my finger in and a rag at the ready to wipe off any excess caulk. I painted on two coats of primer, allowing for 30 minutes of drying time between each coat.

Once your primer is dry it's time to paint your casing. All of the trim work in my house is painted in Alabaster by Sherwin Williams. It's a nice milky white without being too yellow. There will be paint and primer on the walls all around your casing. I just touched it up with some extra wall paint that I keep on hand.

DIY Window Casing | Little Red Brick House

DIY Window Casing | Little Red Brick House

I love how much character the casing adds to the window. I almost didn't want to put my curtains back up!

DIY Window Casing | Little Red Brick House

DIY Window Casing | Little Red Brick House

DIY Window Casing | Little Red Brick House

Thanks again for having me over, Tasha! I hope you all enjoyed my DIY window casing tutorial!  I'd love for you to stop by and check out my other DIYs like my Sunburst Mirror made from wood shims, my complete Fireplace Makeover, and my Wood Crate Table. You can find all of that and more at Little Red Brick House!


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  1. Lauren says:

    I’ve been in love with this version of diy window casing and am geared up to finally start! Only none of the photos are loading :( Only the ads. Feel free to delete this comment, but thought others may have the same issue. Hoping I can view them soon. I’m not brave enough to start cutting boards and filling the compressor without them. lol.

  2. So.Much.Better!! I would love to do this with ours but the wall corners of the windows are rounded so we’d have to put trim on all the insides too :/

  3. Leslie says:

    I love this, I’m pinning. I may decide to update my window casings. This would be the perfect project this winter.

  4. […] hello there and happy Tuesday! I hope you are all enjoying your week so far. Today I am over at Designer Trapped in a Lawyer’s Body sharing how I upgraded my boring builder grade windows with some DIY window […]

  5. Thanks again for having me over, Tasha!

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