I received a new prehung front entry door with right and left sidelights as a gift to replace my extremely aged and poorly installed current front door. The problem is that the new door width is approximately 4.5 inches too narrow to fit into current rough opening. (Actual door is still 36", but sidelights are both a tiny bit narrower, accounting for the size difference). Reframing rough opening can be done easily to account for the newer smaller door width. HOWEVER...

My concern and question to everyone deals with the outside and the siding not covering this new gap of 2.25 inches on each side due that I will create if I reframe a new rough opening to accommodate the narrower width of the new door. Current siding is very old, aluminum, and aged, so matching up siding would probably not be easy, ideal, or possible.

Does anyone have any clever ideas or thoughts on what I can do to accommodate this narrower door with a nice, successful looking door installation? Any thoughts or ideas would be greatly appreciated and thanks in advance for taking the time to read my post.

Thanks, D

  • 1
    You could use some exterior trim or flashing. Aluminum, cellular PVC, or wood are all reasonable options. Jul 25, 2016 at 20:10

1 Answer 1


I agree with S Rura. The only way to do this without messing with the siding is to install a nice trim or brickmold. You will need to install a plywood filler to match the depth from your rough framing to the siding level. Caulk all the seams. Then install some ripped(if necessary) brickmold or other flat trim like painted pine, MDF, or PVC. Then caulk the seams around the door and J-channel again. It will look great. On the inside, just extend the drywall, tape and mud, then install the trim of your choice.

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