I recently had an exterior door replaced with a sliding glass door. The old door was flush with the wall, so when the trim was installed there was no issue.

The issue I have now is the new door is recessed a bit, so it does not sit flush with the drywall. If I installed the trim, there would be a gap behind the trim itself and the door. The question is, how do I fill this gap? This gap varies from 1/2 inch (the thickness of the drywall) up to an inch so caulk is obviously not an option.

The only idea I can think of is to ultimately cut a big "shim" that is the thickness of the gap, but I'm not quite sure how that should then be attached. Would I be able to staple the trim to that?

Any ideas are appreciated. Please see the pictures below and let me know if any more information would be useful.




  • Welcome! Great first question.
    – matt.
    Sep 17, 2023 at 2:11

1 Answer 1


It seems that you have the right idea. Take a piece of 1X board, put it against the frame and mark where it touches the outer edge of the drywall. Then rip the piece with a table saw. Nail molding against this piece. Add a bit of caulk to seal the seams.

  • Agreed. A jamb extension is the correct method to resolve this.
    – matt.
    Sep 17, 2023 at 2:10

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