Installing, measuring and cutting interior window trim

The measurements for the interior window trim need to be accurate because the are highly visible. Still, you can fill in small cracks with silicone unless you’re using natural wood.

If some of the trim measurements aren’t 45-degrees, then you can still find the angles. Sometimes it’s just a matter of holding the two pieces together and marking them where you think the angle should be and then making adjustments to it.

Common sense will be your biggest asset when you’re building your house. If you don’t have much common sense when you start, you’ll have tons of it when you finish.

The door trims are the easiest. You just need to measure to the top of your door, add the width of the trim and you will have the length of the vertical trim pieces.

Cut them at 45-degree angles and then put them in place. Then you just take a measurement across the doorway including the trim on the sides and you have the horizontal trim measurement. Just cut that at 45-degree angles on each side and you are done.

window sill trim

The windows will need something to cover up the rough work. This is one of the few areas that didn’t get covered up with sheetrock. We need to make a frame on the inside all around the window seal.

One of the most popular materials used for windowsill framing is called MDF or Medium Density Fiberboard. It’s actually really tough stuff. You can put it in without any fancy cuts and it will look just fine.

mitering corners

It usually gets silicone in the seams so you can just paint over the silicone and make a great seal against moisture. If you want to miter the ends into 45-degree angles, it will probably fit better, but either way is fine. The window trim is almost as easy as the door trim except you have four sides and they all need to match up so you don’t have big cracks between the trim pieces.

Silicone can only do so much. The photo above shows how to attach the window trim for perfect 45-degree angles. The photo below shows a slightly more complex angle, but still very easy to figure out. The octagon window has been such a big hit with my children.

window trim

Have fun with the trim work. It will show your creativity. The interior window trim can be painted or stained wood. It doesn’t matter just as long as it looks good.

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