I am remodeling my bathroom, and the last step is the tub. The Place for the tub was about 3 inches longer than the tub, so we built the wall out by putting drywall over the studs.

I keep reading about cement backer board and a vapor shield. What are my options as i already have drywall behind the tub (stopping at the tub) but behind it. Can I put roofing tarpaper over the drywall and then secure cement backing, or what?

I'm not sure what to do, this bathroom seems to be build a bit oddly.

See pictures below:

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1 Answer 1


Will it be used as a shower as well? If so, sheetrock is the wrong material for the surround. It's going to act as a sponge if water ever finds its way to it.

What you could do is put backer board on top of the sheetrock, then coat the backer board with a waterproof membrane (I like the Redgard product for that) then tile. Be sure that the backer overlaps the lip of the tub to the inside.

Personally, I'd pull out the sheetrock completely, then shim out the studs and apply the backerboard to that.

  • I still need the tar paper behind the backer board if I go that way? May 11, 2012 at 18:18
  • 1
    In theory, no. Your waterproof membrane is the barrier. Would tarpaper hurt? Probably not.
    – DA01
    May 11, 2012 at 18:38
  • +1 for mentioning RedGuard (floorelf.com/installing-redgard-on-shower-walls-for-tile) The guy I talked to at HomeDepot said if he didn't use it on his jobs, the warranty was void.
    – AlignedDev
    May 11, 2012 at 20:53

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