View Full Version : Bathtub walls
07-26-2008, 10:14 AM
I've removed the tiles and sheet rock from my bathroom walls and have the studs exposed. I've currently got 1/2" hardibacker ready to install and I have to fur out the studs to match the hardibacker up to the old 5/8" drywall. Questions:
1. Where the hardibacker meets the old drywall should I use the regular drywall tape or the fiberglass mesh type tape?
2. Will regular joint compound adhere to the hardibacker?
3. Should I return the hardibacker and get a 5/8" mold resistant drywall to make my life easier?
07-26-2008, 01:17 PM
Use the Hardiebacker. Put a vapor barrier behind it, lapping the bottom edge over the tiling flange of the tub. The sell shims at some lumberyards that make it fairly easy...tack them up, put up the vapor barrier, then the Hardie.
Often, the tile extends beyond the outside of the tub itself. Since that area is typically dry, you can end the cbu there, and put the outer row of tile on the drywall. Use the mesh tape.
If the studs are not plumb, sometimes it is easier to add in sisters to get the whole wall plumb rather than shimming th eold ones out. Keep in mind that with the thinset under the tiles, you may not need as much of a shim as you think. That outer edge only needs a small amount, and the thinset over the Hardy should be plenty. If it was on a floor, that'd be a different thing, but you're not walking on the walls. You don't want that last row to bow out, though.
07-27-2008, 07:16 AM
What exactly should I use as a vapor barrier? I've looked on the web and everyone talks about a vapor barrier under flooring and in attics, but no one mentions it behind bathroom walls (oddly enough). Also, there was no vapor barrier behind the original walls, so is it really needed?
07-27-2008, 09:07 AM
Cement board products are not damaged by moisture, but they are not water proof. Dampness seeping through a grout crack can cause mildew BEHIND the cement board.
4 mil poly sheet is OK. I like 15 pound roof felt.
07-27-2008, 01:42 PM
Got it. So 4 mil poly sheet...that's just a think piece of plastic basically, correct?
07-27-2008, 01:44 PM
0.004" thick...not very much.
08-12-2008, 03:51 AM
I agree with jadnashua 0.004" is not too much.