I have bought a 36″ square acrylic shower base for the bathroom I am remodeling. The plan is to use concrete backerboard and tile on the walls.
My question has to do with the interface between the backer and the base. It is an “alcove” base, with a thin flange around three sides. According to the instructions that came with it, you are supposed to take the wallboard (they say drywall in the instructions) down to the top of the flange, then fill in the space between the bottom of the wallboard and the bottom of the flange with either drywall compound or a strip of wood. Now I’m no expert, but that sounds like an incredibly bad idea.
My thought was to overlap the tile backerboard over the flange by some amount (all the way over the flange?), then tile, then caulk the joint between the tile and the base.
Any pointers? Am I crazy? How would you do this? If it would help I can scan the instruction sheet and post it tonight with a picture of the base itself.
Thanks!
Replies
either fur out all the studs about 1/8th of an inch ....
or if you don't want to rip furring down ... store bought lattice strips(1/4") will work ...
or .... since you are tiling ... I'd run the backer to the top of the lip ...
and simply make up the difference on the bottom row of tile by filling in with thinset ... either by troweling it in .... or adding to the back of the tile .... or a combo of both.
remember to leave your bottom tile up about 1/8 to 1/4 so you have a place to caulk.
Now that I'm thinking about this install ... it'd run my poly over the studs .... and make sure it runs OVER that lip .... then .... backer.
the plastic will hang a little below the backer.
Jeff
Buck Construction, llc Pittsburgh,PA
Artistry in Carpentry
The easy way is to nail the CBU up to, but not over, the flange. The tile will be set over the CBU and over, but not up to, the flange. So the tile will hang over the flange and base by about a half an inch and will be unsupported. The gap is filled with 100% silicone caulk.
Firing over can create some problems with lining up the tile with some bases, in that some bases have fairly narrow "ledges" and if one firs it out the tile may actually not but up to the ledge, but hang over it.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Okay thanks guys, good advice from both of you. It sounds like Boris has the easier solution, so all things being equal that's probably the way I will go.
I hadn't even thought about putting up plastic behind the CBU, is that a fairly standard practice? Just staple it up around the perimeter, I imagine?
And while I have you here, let me ask you this. I have seen some installations where a shower base like this was set in a pile of wet mortar to give it a more solid bearing. Is that a good idea, or should I just use adhesive like the box says?
I have done replacements with older metal pans where I used 1/4" Hardiboard that I butt down to the top of the flange, then went over with another layer of Hardi that came within 1/8" or so of horizontal lip on pan (to leave room for sealant). This allowed the last layer of board to remain flat (ie. not kicked out by the thickness of the flange), so setting tile was easier on the flat substrate. A little more work, but it seems to pass my "where will the water go?" test.
This is a great question for the tile guy from the Cape (CC Tile Works). He is regularly doing articles for FHB. I would rely on him if you can contact him. I think he is in Harwich or Harwichport.
Jeff and Boris have it covered, but I'll throw in my .02 on the last one I did. This was a Florestone neo-angle pan with a lip on 2 sides that's about 3/8" thick and maybe 1-1/2" high. First step was to set the pan in a bed of structo-lite plaster and connect the drain. Pour some water down there so the trap will be sealed. The flanges on the pan were right against the studs. Then I sheeted the walls with 3/8" plywood, bringing it down about 3/4" above the flange. Face of plywood flush with face of flanges. Then I laid up 6 mil poly over the plywood and down over the flanges too. Last was the backerboard which I held up about 1/2" from the top of the pan. The thing I like about this is that it allows an easy and reliable installation of the poly or whatever you use behind the backerboard--you have to use either poly, 30# felt, or if you're really going for it maybe bituthene. Water goes right thru grout and backerboard and will rot your wall if you don't protect it.
Since you all are talking about shower pans, I thought instead of starting another thread I would append to this one. Problem: Customer has tile shower. Was called in to replace several broken tiles and regrout them. Several months later I receive a call from customer that grout has washed away. Regrouted and sealed. Next month same thing. Then I removed the tiles immediately surrounding the drain, removed ~3 inches of motar from around the drain, cleaned the weep holes which were clogged, reapplied mortar after building protection around the weep holes so they will not clog again. Received call last week - same thing. Now looking into either (1) R & R mortar bed down to subfloor and rebuilding or (2) R & R mortar bed and installing a cultured marble shower base. Now for the questions:
1) Which is the best long term solution?
2) Do I need to perform any work from below the shower such as plumbing?
3) What would be a reasonable charge for either solution?
Thanks for your patience and I look forward to any responses,
dlb
The undisciplined life is not worth examining.
What do you mean by R & R? Remove and replace?
Why are so many tiles breaking? The original installation sounds like a problem and I would probably tear it out. You may need to alter the drain, especially if you use a pre-fab base, since they have specific rough-in locations for the drain.
Ask the guy what he's using to clean the shower. I'll bet he's using some sort of acid.
First question. Yes, plastic, about 6 mill sheets should be stapled behind the CBU. This stuff is not 100% waterproof.
Second, a comment. quarter inch Hardi is not recommended for walls as it flexes too much. Use half inch.
Third, moisture is getting to this grout in a big way. I would suspect that there is no preslope. I would try one more time and let the grout cure for a full week and seal it. If it washes away this time, time to R & R, remove and replace.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934