DIY Window Trim – The Easy Way Without Miter Cuts

Learn how to add chunky window trim the easy way without any complicated miter cuts or special equipment.

We have been going a mile a minute here lately with our latest addition being the window trim!

As we’ve been getting closer to the finish line of Olivia’s bedroom makeover, we’ve been working around family vacations, reunions, and summer day trips. It’s exhausting but in a good way!

This certainly isn’t one of those gorgeously creative DIY posts, but this little project is by far one of my favorites for adding some oomph to a room.

My favorite thing to DIY in our very plain builder box house is adding architectural interest, and since we’ve already done similar trim in our master bathroom, I find myself drawn to the idea of chunky window molding throughout the rest of our house.

You can find all kinds of versions of this similar trim all over the internet, but this is our very simple take on interior window trim.

More ideas to add character to your home

• 8 DIY-able Wall Molding Ideas to Add Character to Your Home
• How to Quickly Beef Up Crown Molding and Baseboards
• The Best Paint Colors for Gray Trim

Olivia’s bedroom window was uh…lack luster. Blah. Boooooriiiiiing.

I mean, what’s a bedroom with a glamorous chandelier without some pretty window trim to go with it? That’s like wearing stilettos with your jogging shorts. Joan Rivers would have never forgiven us, bless her soul.

This trim is so easy and doesn’t require any fancy schmancy miter cuts. If you can cut in a straight line, you can do this. I pinky promise. So here’s how to trim a window.

DIY Window Trim – The Easy Way Without Miter Cuts

Window Trim Supplies 

• 1×2 (length depending on the size of your window)
• 2 1x4s
• 1×6
• Brad nails
• Wood screws
• Hammer (If you want to get the job done way faster, this cordless nailer rocks.)
• Trim caulk
• Wood filler (for wood knots and nail holes)
• Primer (always prime raw wood before painting)
• Paint (I used a sample size of Valspar Du Jour and it was just enough.)
• Jigsaw (of whatever type of saw you prefer)
• Nail setter
• Fine grit sandpaper

The Steps

Here’s the game plan. A visual is probably easier for this one.

Make the Window Sill

1. We started on the window sill first. Cut your 1×6 to the width of the window plus 10 inches to leave an excess of 5 inches on each side.

2. Once we had the width of our 1×6 cut, we held it up against the bottom of the window to mark where to cut out the corners to fit into the window base.

3. Once everything looked good, we used the brad nails to attach it.

Add Window Trim Sides

4. For the sides of the trim, we held our 1x4s up on each side of the window to mark where to cut the length.

(Measuring is overrated in our house for some projects. If we can get away with lining up wood pieces, marking, and cutting, we do. It’s easier and just as accurate as going the extra step with a measuring tape.)

Assemble the Header

5. Once the sides of the trim were up, Robert got to work on the header by cutting the remainder of the 1×6 the same length as the window sill. He cut the 1×2 in two pieces using the same length as the 1×6.

6. I didn’t get a shot of him using wood screws to secure the 1x2s to the top and bottom of the 1×6, but you can get a good idea of it from the pictures. (Sometimes I’m just in awe of his mad skills and wonder to myself how I ever got so lucky for marrying such a handy guy and forget to pick up my camera…oops.)

7. He used brad nails again to attach the header to the top of the window and made sure to secure them into studs in the wall.

Add the Apron

8. He added a length of 1×4 under the window sill too (called the apron).

9. Caulk any gaps and wood fill knots. You can get a better idea of how the 1x2s are attached to the 1×6 from this angle. See that not so pretty gap between the wood and the wall? Caulk is your best friend.

Just so you know, I posed with my caulk gun doing an oh-so-sexy Charlie’s Angels pose and somehow it mysteriously disappeared from my memory card.

Okay, you caught me. Turns out, I’m not good at oh-so-sexy Charlie’s Angels poses. More like awkward Mr. Bean face.

Good thing my caulking is better than my modeling.

Set Nails, Wood Fill, Sand, and Caulk

10. I went back over the brad nails with a nail setter one more time to make sure none were sticking out too.

11. I gave the nail holes a fill-in with some wood filler, let dry, then sanded. 

Prime and Paint

12. Prime one coat on the raw wood so it will take paint more evenly and the wood knots won’t bleed through. 

13. Paint 1-2 coats in the color of your choice. We used Valspar Du Jour. 

After two coats of white paint, Olivia’s room suddenly looked so much bigger! I kid you not. And now Joan Rivers would approve of our ensemble.

I have curtain panels ready to hang too, so this window is going to look so much bigger from the boring plain one before.

The Finished Window Trim

Amazing how much a little wood and paint can do, right? Also proof that caulk and wood filler can forgive a lot of sins. 

Once the curtains go up and the area rug I ordered arrives, this space will really be singing…er dancing. I mean this is a ballerina room after all.

What do you think? Is DIY window casing a project you could handle?

Robert is already eager to trim our living room and dining room windows, and I’m totally on board.

Update:  See the full bedroom makeover reveal here!

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