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Exterior Door for Odd Sized Opening and 1.5x3 Framing?

Exterior Door for Odd Sized Opening and 1.5x3 Framing?

Old 10-10-05, 10:39 AM
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Exterior Door for Odd Sized Opening and 1.5x3 Framing?

I live in a ranch house built in 1950. The exterior walls are NOT 2x4 construction (about 1.5x3??) and the doors are 36x79 (the outside of the door framing measures 37 and a quarter by 81). I know I will need to have a custom door made. I haven't delved into the world of doors and windows yet (I'm still working on electrical etc.). What should I look for in a custom sized door? Do any of you have advice/experience with thinner than normal walls? Thanks.
Old 10-10-05, 05:41 PM
Join Date: Mar 2000
Location: Arlington, WA
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Welcome to DoItYourself.com and the Door and Window forum.

Let's take this one step at a time.

Wall thickness really shouldn't be an issue if you get creative. Your exterior walls are framed with something about 1/2" narrower than a 2X4. That means that the overall thickness of the walls (from the interior sheetrock or plaster surface to the surface of the exterior siding) should be about 4". A standard prehung door comes with a jamb that is 4-9/16" (for a 2X4 wall). It's simply going to be a matter of using the right trim (I would do it on the interior side, so that it's out of the weather) to compensate for the thickness difference.

The width of your rough opening needs to be 37-1/2" to 38" to install a prehung door that is 36" wide. That gives you plenty of room to get the pre-hung unit in and shim as needed to compensate for an out-of-plumb rough opening. If need be, you can always remove one of the 2X trimmer studs (from the header to the floor) and replace it with a piece of 1X. That will gain 3/4" of width for you.

The height of the rough opening needs to be 81" to 82" to slide a pre-hung door into the opening. Sounds like you are either there, or very close to it. You can use a Sawzall to cut 1/2" off of the bottom of the header if need be. Or, you can take the threshold off of the prehung door, CAREFULLY cut each leg of the jamb, then cut the same amount off of the bottom of the door. Put the unit back together, and it should slide right in the hole.

I really don't think you need to go to the expense of a custom door if you spend a few extra hours and make a standard pre-hung work.

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