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Trim Tips for Doors and Windows

Construction How-To, Finish Carpentry, Mantels. Trim, Molding, Trim Carpentry June 28, 2009 Sonia

Pro Moves for fast and Accurate Casing

Ever been impressed by the skills of professionals? I love to watch professional hockey, probably because three times a week I play the game in a local league. Although I have learned a thing or two watching the NHL, I will never come close to matching their speed and accuracy on the ice.

When it comes to door and window casings, however, you can learn skills to match professional finish carpenters, which will greatly improve your speed and accuracy. A house with 20 doors and 20 windows will need 200 individual pieces of casing to trim out the interior. That’s 200 boards that will need to be measured, cut, fit, glued and nailed into position.

Professional finish carpenters must find efficient ways to get this job done. You may not have plans to go pro as a trim carpenter, but you can benefit from pro tips in casing preparation, cutting multiples, consistent nailing sequence and precise adjustments.

Beat back the drywall that sticks out beyond the door jamb of the window surround. Be careful not to damage the jamb, and to stay within the borders of where the casing will be installed.


Getting the door jambs and window surrounds ready for casing varies a bit between remodel and new construction. Whether you are removing nails left over from the old casing or you are cutting off shims and beating back drywall on a new construction project, it’s important to make sure that all of the windows and doors are ready before getting started.

When the corner of a surround sticks out past the wall surface, you can expect the casing will need to be rolled or back-cut to make the adjustment.

We pull all of the doors off the hinges and set them aside. This really helps in prepping the door jambs. After cutting off any overhanging shims and beating back drywall (within the bounds of the planned casing), use a gauge block to mark the reveals on both the door jambs and window surrounds.

When the corner of a window surround is slightly recessed, the cuts will need to be slightly less than 45 degrees to make the miter work.

Make a list of the doors that need casing. Take note of which doors are exterior doors. Because the stops are constructed differently, like-sized exterior doors will have slightly different casing lengths, so cut these separately.

Use a gauge block with a 1/4″ rabbet to mark the reveals on the jambs and the surrounds.

Make a list of the window surround sizes as well. Often you will have a parts cut list from building the surrounds that can be used as a reference for the windows. The important thing is to determine which windows have matching horizontal or vertical measurements.