Replies

1. 
   Matt | Jan 16, 2006 02:28pm | #1

   OK - I give - what is "hot mopping"?  I can guess, but we don't use that process where I build... Maybe we should?  For showers, the plumber installs a rubber like liner for the pan and about 12" or so up the wall.  Then a vaporbarrier is applied to the studs, then wonder board, mud bed, etc. 

1. 
   brie | Jan 16, 2006 07:30pm | #2

   hi matt,
   'hot mop' is a tarry substanced mopped on to the shower pan floor and up the wall 10" or so. it's what installers here in california (l.a.) have been doing for years. i've heard that eventually, they all fail, (earthquake country) whether it's a couple of years (bad job) or 20 years (great job.) i'll look into the system you spoke about. i'm doing most of this remodel myself, so the membrane is something i might be able to do.
   my main question, though, is do i have to waterproof the tub deck as well, before i wonderboard it?
   thank you for your reply,
   brie

   Edited 1/16/2006 11:32 am ET by brie

1. 
   davidmeiland | Jan 17, 2006 05:36am | #3

   The most commonly recommended shower pan liner is Chloroloy or Noble CPE. They are heavy, flexible membranes that have proprietary glues and sealants, outside corner pieces, etc. You can do a little Googling and learn quite a bit, or visit johnbridge.com and read the forums there for all the info you need. I don't think hot-mopping is used much any more, although it was common a while back.

   I've done a couple of showers with Chloroloy and it's a good material, not hard to work with. If you need to get waterproofing behind your tile it's probably what you should be using.

1. 
   BillBrennen | Jan 19, 2006 06:25am | #8

   Hi David,You stated, "I don't think hot-mopping is used much any more, although it was common a while back." That is probably true where you are, and it was true for me in Colorado, but hot-mop is still very common here in SoCal. I think it is a lousy system with a short life and high failure rate. But it is still popular here. So much of construction practice varies by region.Bill

2. 
   dirtysanchez | Jan 18, 2006 01:33am | #4

   try ice and water shield from grace.

    

3. 
   Matt | Jan 18, 2006 01:21pm | #5

   OK - nobody really answered your question with anything that sounded like authoritative experience so I'm gonna ask a Q- is it necessary to waterproof the deck for a drop in tub?  I mean it makes sense, but to tell you the truth I don't do it and am not particularly worried about it as I've never actually heard of one of these decorative garden tubs being used a lot, especially since there are almost always installed in a bathroom with a separate shower.  If it were going to be used as a shower/tub that would be different.

1. 
   davidmeiland | Jan 18, 2006 06:18pm | #6

   I put 30# felt under the CBU when tiling a tub deck. A lot of tubs get used plenty, and some by kids, who splash water out onto the deck where it may or may not get wiped up after the bath. The bottom of the CBU will eventually get damp, and I'd rather have something under there to protect the plywood.

1. 
   brie | Jan 19, 2006 05:27am | #7

   thank you all for your responses. i've decided to waterproof under the cbu--can't hurt! we don't have young kids, but a future owner might.

4. 
   Wango1 | Jan 19, 2006 08:04am | #9

   Avoid the hot mopping and use Kerdi from Schluter. Mortar above and below and you'll be fine. Don't use tar or even tar paper. The holes will undermine the very waterproofing.