For Week 7 of the One Room Challenge I’m showing you how I added DIY window trim to my daughter’s room! All of the windows in our home don’t have window trim or window sills. I wanted to try my hand at adding window trim to add character to the room.


Thank you to Handy Products who supplied materials for this DIY project.
Affiliate links are used for your convenience. I may receive a small commission if you make a purchase through my links.
The One Room Challenge is coming to a close with reveals coming very soon! I’m excited to finish up my daughter’s room and show you all the final reveal. You can head over here to see the rest of the guest participants and the featured designers updates for this week.
WEEK 1 | WEEK 2 | WEEK 3 | WEEK 4 | WEEK 5 | WEEK 6 | WEEK 7 | WEEK 8
DIY Window Trim
When we first moved into our new home last year I noticed something. All the windows (and walls) had bullnose corners (which I have dealt with before). Another thing the windows lacked were window sills and window trim.
There isn’t anything wrong with this, but to me it looks unfinished – like something is missing. I wanted to add some character to the window (I’m a sucker for craftsman style trim), so I did some research on DIY window trim. I found some amazing tutorials like this one from Blesser House and was inspired to try it on my own!
When I began planning out this room makeover I had my heart set on a cordless bamboo roman shade. It would add some texture and interest to the room, plus is safer for children to operate. And I get annoyed with pulling the cord of the heavy wood blinds up and down every day. I’d like to make it easier for everyone π

I had to plan out this project by doing lots of measuring. Measuring the width of the window, searching out the correct size of the bamboo shade I needed, researching what kind of wood to use for the trim, measuring and figuring out if I’d be able to mount the shade inside the window after the trim was added, etc.
Finally I came up with a plan that would work for the space and give me the look I was going for. It took a lot of planning for sure, but I think the end result is worth it. And now that I’ve figured out how to do this project I can more easily add trim to the other windows in our home!
Materials For DIY Window Trim
- Common boards / MDF (for window trim)
- Hard wood / Eucaboard (for inside the window)
- Nail gun (this is the one we use!)
- Measuring tape
- Pencil
- Miter Saw
- Jigsaw or Table Saw (I used a Jigsaw)
- Caulk
- Wood Filler
- Sandpaper
- Primer
- Paint
- Paint brush
- Handy Products (I used the Handy Pail, and Handy Roller Cup)
How To Add Custom Window Trim
First I started by taking measurements of my window, gathered my materials, and then purchased the wood. For this project I needed to purchase (2) 1x5x6 common board for the window sill & top trim, (1) 1x4x8 common boards, 1 1x2x8 (for the top trim), and some hard wood (also known as eucaboard) for the inside of the window. I already had a couple of MDF 3 inch wide boards that I could use for the sides of the window.

In order to have my bamboo shade fit properly, I needed to use a very thin board for the inside of the window. I found the eucaboard was the perfect measurement at only 1/8 of an inch of thickness. Since the boards would all be primed and painted, the color difference of the wood didn’t matter in the long run.
The first piece I measured for and installed was the window sill. I used a 1x5x6 common board for this piece. I measured the width of the window, added 6 inches (width of (2) 3in MDF boards), plus another 2 inches of overhang that will extend past the side trim (1 inch on each side). After I used a jigsaw to trim this piece, I used a nail gun to install it.

Next I measured and cut the eucaboard for the sides and top of the inside of the window. This is the step that helps hide the bullnose corners of the window. I cut the eucaboard with a jigsaw (table saw would have been better, but I used what I was comfortable with). Then I nailed in the sides and top piece with the nail gun.
Then I worked on adding the side trim pieces. I measured and cut the pieces for the sides (using the 3 in MDF boards), then started nailing them in. Then I cut and nailed in a 1×4 piece underneath the window sill.


Lastly I cut and nailed in the top trim pieces. First by cutting and nailing in the 1×2 common board to a 1×5 common board the same length as the 1×2, to add some thickness to the top.
After all of the wood was nailed to the wall, I started on caulking and filling the nail holes with wood filler. I caulked the edges where the wood met the wall, and also any gaps between the wood pieces. This step is key, and gives a smooth and professional finish. I use my fingers to smooth it down, and use baby wipes to clean off any excess.
RELATED: HOW TO PAINT OAK CABINETS


I love using this plastic wood to fill nail holes, and fill in any knots in the wood. I apply it with my fingers, but you can also use a putty knife to apply it to the wood. When it is dry to the touch, simply sand it down smooth and you’re ready to prime and paint.
Here is a look at the trim after the holes and seams were filled in!

My New Favorite Painting Products
The finishing touches included priming and painting everything, and for this step I was SO thankful for my Handy products! My favorite features of the Handy paint pail are the magnets for holding your paint brush, and the removable liners. The fact that I can toss the liner after I’ve finished with my project is so convenient, and keeps the pail and tray clean and ready for the next project.



If you have done your fair share of painting projects, you know how inconvenient it is to carry around a paint can and have to find a place to set down a paint brush covered in paint. Using the Handypaint pail is a game changer, with its adjustable handle to take the pressure off your hand. Having the built in magnet to hold your wet paintbrush is SO helpful so you have a free hand to climb a ladder, grab a towel, or even refuel with some iced coffee π
I used my Handy products for painting the window trim, and will be using them for all my future painting projects! And trust me – there are a lot of future painting projects coming soon!
Here is a fun before and after of the window! What do you think of the difference? I love how much style and character it adds to the room!




Girls Bedroom To-Do List
Paint the wallsApply Wallpaper(Did you see my wallpaper accent wall?)Paint the twin bedPaint the dresser(Check out the post if you missed it!)DIY window trimAdd roman shadeAdd wall sconce lightPurchase a new side table(I found one that fits the space perfectly!)Add a new rug(My post last week gave you guys a peek at the new rug!)- Decorate (the very last step!)
We are SO close to the reveal! I am waiting on a couple items to arrive, and then I can work on decorating the room! I’m so happy to finish up this bedroom makeover for my girls. They have been loving all the changes I have made so far!


