I would like to divide a room into two rooms with a dividing wall. Should I remove a portion of the ceiling drywall, and drywall on abutting walls, and should I remove the portion of the subfloor to attach the new partition framing directly to joists, studs and floor joists?

2 Answers 2


You're asking a simple question and I'll provide a simple answer but in order to meet building codes this may get a little complicated for you.
Yes- You will need to remove drywall and attach the framing of the new wall to the existing framing. There shouldn't be a need to cut through the subfloor. The baseplate or footer of the framed wall can attach directly to the subfloor.
However, beyond that it gets more complex. You will need to get a permit and check your local codes. Constructing a separate room will need to meet codes regarding ingress and egress, electrical (light switches, outlets) and possibly other requirements such as a closet if you want it to be classified as a bedroom. You will also need to think about heating and cooling which may require adding ductwork or baseboards. In other words it's not as simple as just building a wall.

  • 1
    Why is it necessary to remove drywall above the framing? Can't the top plates be attached through the drywall with sufficiently long fasteners?
    – Matthew
    May 4, 2021 at 5:39
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    Think one is you are guessing where the nails go/into cables, and the other you know what you are nailing into.
    – crip659
    May 4, 2021 at 10:22
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    If you don't remove the drywall, A) You may hit plumbing or wiring with fasteners, B) You may NOT be hitting a stud/joist with those fasteners. If B, now your new wall is held up by nothing but drywall, which means if someone trips and hits this new wall, they may move the whole wall. It means that if someone in the future cuts away the drywall to do some repairs, the new wall is supported only by the drywall attached to it, which is now attached to nothing. Attaching it to subfloor is different - walls are normally built on the subfloor, so this is expected.
    – FreeMan
    May 4, 2021 at 12:47
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    Thank you for the answer and warning about codes. This specific area was designed for two rooms, but the original owners decided to not install the dividing wall. All other houses in the same complex have two rooms in the same area, and it already has separate ductworks and windows.
    – ipavlic
    May 4, 2021 at 16:07
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    You're welcome. It's always a good idea to only attach structural material to other structural material that's clearly visible. Otherwise, as indicated by @FreeMan, it can be hit or miss.
    – HoneyDo
    May 4, 2021 at 18:57

No. Many a partition wall has been installed right over the existing drywall. I've done so many times myself when remodeling homes for myself and others.

If you're able to attach the wall top and bottom it's not going to be a problem. Some construction adhesive behind the stud against the old drywall will prevent cracks in the new tape joint.

Fasten your new wall in as many points of indirect contact with framing as you can. Give it the thump test to see if it feels solid. Unless you have some extraordinary loads planned for it there won't be an issue.

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