Replies

1. 
   calvin | Nov 02, 2010 08:38am | #1

   I take it this isn't going to be a tub shower combo.

   Which if it was, you should do a better job of a water tight backing.

   Still, I think I would at least apply Red Guard (or other) waterproofing brush/roll on membrane within range of the tub deck and up the corners a ways b/4 tiling.  Thinset should stick to your painted plaster wall-if you feel you'd like to rough it up a bit first-won't hurt.

2. 
   DanH | Nov 02, 2010 06:26pm | #2

   If the plaster has survived this long in good condition, and you're not changing the arrangement somehow so that the walls will get wetter, then you should have no problem.  Make sure any loose paint is removed, and use a mastic, not thinset.

   If you're planning to change the configuration such that the wall will be getting much wetter, though, the plaster should be removed and replaced with cement backer board.

1. 
   calvin | Nov 02, 2010 07:35pm | #3

   Dan, why mastic not thinset?.

   .

1. 
   DanH | Nov 02, 2010 08:09pm | #4

   A) You don't need thinset (nor generally desire its added thickness) in (reasonably) dry areas.

   B) The mastic will adhere to the paint better, without the need to scarify the wall.

1. 
   calvin | Nov 02, 2010 08:22pm | #5

   I went the otherway because

   Some mastics caution against use over added membrane waterproofing (as I mentioned RedGuard down low and in the corners)

   and additionally in "wet" areas, mastic could soften.

   We probably could confuse most anyone-given enough time.

   And for all we know, the tub is a clawfoot and the wall isn't even connected.  Sure wish these folks would come back in a timely manner to fill in the gaps.

   But then again, the crawler on the bottom of the tv just presented us with the very important tallies on our local and regional elections.  Right over the great legs on Dancing with the Stars.  Guess what the percentages are for those precincts reporting and votes cast?

   0%

   Now, that's timely reporting.

1. 
   DanH | Nov 02, 2010 08:53pm | #6

   He said it's plaster on lath and still in good condition.  I take that to indicate a dry area.  No need for membrane.

2. 
   Piffin | Nov 03, 2010 09:32pm | #7

   Odds are, that plaster on metal lathe has tarpaper behind it.

   But if old house and wood lathe, i'd question how good it actually is. I have been patching/repairing/skim coating plaster for a couple of weeks on and off now

3. 
   DanH | Nov 03, 2010 09:59pm | #8

   Any sort of plaster on lath that has survived this long is in a dry area.

4. 
   Piffin | Nov 03, 2010 10:17pm | #9

   "Any sort of plaster on lath that has survived this long is in a dry area."

   The house I am working on would disagree with you on that