neetlydone
- May 22, 2021
- 3 min read

DIY Window Trim

Updated: Jul 21, 2021

How to create window trim to elevate your builder grade windows

When picking out all the options for our new construction home, we chose to add some finer details like chunky crown molding and wainscoting in our entryway but that was the extent of the millwork that was offered by our builder. All our windows throughout the house were energy efficient and we are glad for it but they were as bare as they come. After a few weeks of nothing on the windows, we called in a company to measure all our windows and ultimately install blinds.

Even with blinds, the windows always looked unfinished so as I update decor in each room now, I am adding in simple window trim that completes the windows and adds to the overall design of the room. When looking for inspiration on what kind of trim I wanted for my house, I considered a few things:

a style that is simple to create but provides enough detail to add a custom look
a style that works for all windows in the house
a style that works with other elements in our house (clean lines/transitional)

I decided on a craftsman inspired style for the window trim. I like the clean lines of this design and I feel that it could go with a variety of decor styles. I kept it simple and just used primed pine boards from Home Depot in varying widths to create this look. You could add more molding details for a little more traditional flair. Here's a diagram showing how it looks and all the sizes for the boards I use:

Window sill - 1"x5"
Sides - 1"x4" (one on each side)
Strip under sill - 1"x4"
Header - 1"x2" (one for top and bottom), 1"x5" (for middle)

I like the clean lines of this design and feel that it could go with a variety of decor styles.

The most time consuming part of this project is cutting the window sill. I make sure that the overall width of the sill is the internal width of the window + 2 x side piece width + 2 x 0.5" overhang. To cut the profile of the sill I typically use a jig saw. It took me some time to be able to cut straight with the jigsaw but I found that once I had the technique down, it's the most efficient tool for the job.

The rest of the pieces are all cut with a miter saw to the appropriate lengths based on window dimensions. I use liquid nails to glue down the sill before nailing in place and that's the first piece to get installed. Then I add the sides and bottom and finally install the header from bottom piece to top. Once the sill is in, the rest of it comes together within minutes.

The most time consuming part of this project is cutting the window sill...Once the sill is in, the rest of it comes together within minutes.

To prepare the trim for paint, I caulk all the seams (pine to pine as well as pine to wall) and fill in nail holes with wood filler. Once everything is dry and sanded smooth you could paint the trim the same as your baseboards or in my case, the same color as the wall. Typically window trim lends itself well to satin finishes or glossier so it can be wiped easily.

I have added window trim to 4 rooms so far and hope to finish the rest of the spaces soon! Check out below for imagines of the updated windows.