How to true old wall before hanging drywall?

Discussion in 'Remodel Forum & Blog' started by jch, Mar 18, 2007.

  1. jch

    jch Member

    I am about to gut a 60-year-old plaster-and-wooden-lath bathroom.

    Trying to anticipate any potential issues *before* I take the room (and our only shower) out of commission...

    I'm moving a lot of pipes around so am going to need to pull down the plaster and lath. Will then replace it with cement board (or equiv).

    1) How likely is it that the studs will not be planar/plumb? I'm thinking that they wouldn't have needed to get the wall that straight when they originally built it since they were going to cover it with ~1" of plaster anyway.

    2) If the studs are out of whack, what's the best way to create a true (plumb/planar) surface to hang the drywall on?
    - Small shims?
    - Horizontal strapping?
    - Full height shims?
    - sistered studs?

    Appreciate any help. Searched this forum but couldn't find anything on this.

    Thanks!
    .../j
  2. prashster

    prashster New Member

    Messages:
    941
    If yr studs bow inward < 1/8" but are in good structural shape, I'd first try to shim since it's easiest. More signif, I'd sister or at least add sister blocking at 0", 48" and 96".

    For outward bows less than 1/4", I'd plane the surface. If that doesn't work, I'd cut kerfs every 12" on the convex side and nail them tight to try to fix the bow. If that didn't work, I'd just replace the stud.
  3. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Depending on the situation, ALL of the techniques you mentioned may come into play. Get a long very straight "something" to test with. A 6 or 8 foot level will be good. You can use a 2X4 if you find a really good one, especially if you have access to a jointer to true up one edge.
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,324
    Location:
    New England
    You could sister with metal studs...they should remain straight and won't warp when they dry out or shift with the seasons.
  5. prashster

    prashster New Member

    Messages:
    941
    Speakin' of shrinkage. If yr gonna use wood, just make sure you use KD not GRN. I used GRN on a dropped header. The wood shrunk about 1/8"!, pulling in the drywall and causing a huge crack.
  6. jch

    jch Member

    Wow--thanks for all the tips so far! :)

    I have a more fundamental question. How do you even start out telling *where* you need to shim to bring it back into plane?

    ** How do "the pros" quickly suss out a stud wall to see *where* the problems are (and, more importantly) where to fix them??

    I was thinking that I could nail up strings diagonally across the stud faces and see where I get gaps. I would expect that these strings, combined with moving a long straight edge across the joists and using a level down the face of each stud, would tell me where the problem areas are. But I'm not sure.

    And, by "shims", are you referring to pairs of wedge-shaped pieces of wood (like you use with window/door frames)? Or specially-ripped custom-thickness rectangular pieces? Or something else?

    Thanks!
    .../j
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,324
    Location:
    New England
    Shims could be any or all of the above, depending on the condition. A plumb bob and a straightedge along with maybe a good framing square should tell you what you have. A level would be an asset, too.
  8. prashster

    prashster New Member

    Messages:
    941
    Be a little careful that you don't split any shims you use.

    Slide a 4', 6' or 8' spirit level across neighboring studs and feel for rocking an look for gaps. It doesn't have to be perfect. Less than 1/8" and the dwall will hide it.
  9. leejosepho

    leejosepho DIY scratch-pad engineer

    A 4' level will tell you a lot both as a simple straight-edge and in checking for plumb. Place it against each stud vertically and see what you have there as far as straight and/or plumb are concerned, then press it against the wall horizontally at various places around the room to look for flat. Unless something is way off, I never bother with 1/8" here or there, and other fixes are dependent upon what a given wall surface will actually be doing. Keep in mind that most walls look just fine until they are stripped, and they will again look just fine after they have been covered again. The worst one I have ever fixed was the center, load-bearing wall here in my own house just a few weeks ago, and it was so bad that I had to actually cut part of the way through some of the bowed studs before sistering some straight ones in place.
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