We just replaced an old sliding glass door in our house, but the new unit has a jamb that is about 1.5 inches narrower then the old jamb. We've decided to do a decorative tile strip for the floor, but I haven't settled on how to handle the interior trim. Should I tack a wood strip to the edge of the trim to cover the gap or something?

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Yes, google "jamb extension", and you'll get plenty of instruction.

The only quirk to watch for is that the width of the jamb extension will sometimes vary because the door/wall relationship isn't perfect.

One approach is to exactly scribe the extension to the plane of the wall. This is time-consuming but pretty.

If you have the jamb extension proud of the wall, then applying casing will be a pain.

If the jamb extension is not wide enough to come up to the plane of the wall, you can hammer the drywall (underneath where the casing goes!) to make it flush.

A modest gap between the door and the jamb extension can be filled with painter's caulk.

All in all, caulk is your friend.

  • Thank you! I was unaware of the existence of Jamb Extensions. – dbonomo Mar 5 '15 at 21:09

I had a similar problem when I replaced my windows. I just sealed the opening with a foam sealer and added a finishing board on the inside of the stud and attached the molding to the finishing board I installed to close the gap between the window and the studs. The only problem you might have is if you want to match the original molding which now may not fit.

  • Good suggestion. This is close to what I was originally thinking before learning about Jamb Extensions. – dbonomo Mar 5 '15 at 21:10

Ah yes, "caulk is your friend." Every good carpenter has a great painter in his hip pocket! However, if the jamb isn't set, I think you'll find you may get a better finshed product, with less trim work, by attaching (screwing) the jamb extender to the jamb prior to setting, thereby making it part of the unit. Leave the extension oversized to allow for scribing, if necessary (dry fit first). If the jamb is already set, make sure it is SECURE (I'm assuming an exterior wall) and weatherproof! Don't get sealeants on surfaces yet to be trimmed. Build the "jamb extender" in place (essentially trim in this instance). As with all trim, careful measuring, cutting, scribing, and lots of patience are key. Don't reuse trim unless matching is a problem and then carefull cleaning and sanding is necessary prior to reinstallation. I personally, don't know how to properly do such a project without a table saw, which could be a big problem. That being said, try to match the finishes in the room as much as possible and take your time cutting and scribing if you want the finshed product to look like you bought it that way. Special attention to exisiting conditions such as wall plumb, square, trim reveals, etc. will help greatly. The cleaner the install, the faster and easier the finish (paint and caulk). Finishing the floor first should simplify the trim out. I hope I've avoided enough slang to make this readable. I've been in your spot more times than I care to admit and I wish you good luck! A plumb bob never lies but a plumb wall in a crooked room always tells the truth. If not structural, match existing!

  • Thanks for avoiding the slang! Diving into this project has exposed me to quite a lot of Jargon. I've already set the door, but I have a much clear-er idea of how I'm going to finish this project now. Thanks! – dbonomo Mar 5 '15 at 21:13

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