How To Transform Your Windows With Trim

Thinking about updating your windows, but unsure where to start?

Adding a new trim might be the best option for you.

benefits of trim on windows

We have outlined the easiest way to install and transform your windows so your house looks fresh and updated, just in time for summer.

It’s best to start at the top when installing window trim.

Start by cutting a 45-degree angle on one end of the trim and hold it so the short end of the angle overhangs halfway, or 3/8 in., onto the jamb.

Then mark the other end flush with the inside of the jamb.

That’ll give you a 3/16-inch reveal.

Next, start to cut a 45-degree mitre on one end of the trim board.

Update and adjust the saw as needed for a perfect fit. Then scribe the cut length 3/16 inch past the bottom of the jamb.

Nail the trim onto the jamb first and then to the window casing framing, as you did with the top piece.

Lock corners, glue and pin together the mitre from both directions with 1-inch spaces.

Be sure to have a damp rag ready to wipe away any glue that squeeze-out.

Repeat all the same steps on the other side of the window, fitting first the top mitre, and then marking and cutting the bottom one.

Nail the window casing trim into place.

Fit the First Bottom Mitre: Start the bottom piece. Cut an overly long piece of window casing trim and cut a mitre on one end. Overlap the far end to check the fit. Mark and recut the mitre as needed for a perfect fit.
Fit the Opposite Mitre: Cut a test mitre on the other end and check the fit. Adjust the mitre as necessary until you’re satisfied with the joint.
Scribe for Length: Mark the final cut. With the saw still set for the previous mitre, flip the trim over and scribe the length for the end that has that mitre. Transfer the mark to the front side and make the cut.