Do I need a membrane behind my backer board before I tile shower walls? I have a fiberglass bottom.?

Question

There's electrical behind the backer board, so I'm concerned. I have cut and screwed in the backer board, but I can remove it if necessary now to do things right. As it is, the backerboard (1/4") overlaps the lip/flange of the shower. I found out I am supposed to use fiberglass tape and mud for the seams, but I just want to avoid the possibility of water seepage at all. Should I put up a membrane, or is that moot since I'd have to screw holes through it to reattach the backer board?

Answer 1

you may want to check the building code for where you live to answer that question. call the building permit office to have your question answered.

you don't say what kind of electrical is behind the backer board. is it a junction box or just romex? is the control head for an electric shower or something else?

generally you want to make sure no water can penetrate the backer board and wet the electrical to cause a short or bridge current to your shower head and knobs.

(this answer stolen from - http://www.floorstransformed.com/ceramic_tile/messages/20697.html)
(1) You should use a vapor barrier -- which is different from a waterproofing membrane. Mositure vapor can penetrate tile, grout joints and cement board, so the barrier is intended to keep your studs and inside of walls dry and less prone to mold, etc.
(2) 6 mil clear plastic sheeting seems to be what gets recommended most around here for the vapor barrier; some people use roofing felt.
(3) staple it to the studs before screwing on the backer;

The plastic sheet should come over the lip of the tub or shower pan so that, if any liquid water does get through, it will end up between tile and tub lip and not inside the walls. Because the vapor barrier can direct water between the tile and tub lip in the event that liquid water does get through your tile, consider leaving a small weep hole somewhere along the line where the bottom course of tiles is caulked to the tub rim.
(/end of stolen answer)

from what i have seen the general practice is to put 6 mil vapor barrier over the studs then put up the backer board. if your really paranoid you can use those stainless screws with the rubber gasket.

over the backer board you'll want to apply your water resistant membrane. Schluter-KERDI has a great product that applies over the backer board with thinset. you'll overlap the seems by 2 inches. over the membrane you'll apply more thinset and apply you tiles directly to that.

here's their page. http://www.schluter.com/1324.aspx

you can also check at your local home depot or lowes for a class or just ask in the plumbing dept. my advice is to go with the Schluter-KERDI membrane.

Answer 2

This Site Might Help You.

RE:
Do I need a membrane behind my backer board before I tile shower walls? I have a fiberglass bottom.?
There's electrical behind the backer board, so I'm concerned. I have cut and screwed in the backer board, but I can remove it if necessary now to do things right. As it is, the backerboard (1/4") overlaps the lip/flange of the shower. I found out I am supposed to use fiberglass tape...

Answer 3

Lowes Backer Board

Answer 4

My plumber who (fitted a shower head mixer faucet in the shower end of my bath) said I should tile UP to the TOP of a shower area, as the 'condensation drips downward 'and will get behind the edge of the tiles and weaken their grip on the wall. Which is a bit dreary for me, as I have painted a Gainsborough-esque mural of white clouds all round the bathroom at the top of the walls,where they blend into a blue sky (abutting the ceiling which is all blue sky). What I didn't want to loose was the clouds above the shower cubicle. Having a hard edged slab of white tiles from floor to ceiling (slammed in the corner where there should be 2 foot of cloud tops) somewhat ruins the continuity of 'appearing to be bathing in a cloud'. Hence, I've still not tiled to the top, and despair of the future. If you have no (hours of hand grafted) murals to worry about - tile away to the top. At least they'll stick fast and (to quote my plumber) " won't 'Melt Off The Wall' after time ".... which would be a depressing prospect.

Answer 5

wow, some of these answers are terrible, I like the one where the guy says dont worry about taping and mudding the seams or the other one that said just double up the backerboard lol. Anyway, you should have a vapor barrier of some sort. Since you already put up the backerboard, you should tape and mud the seams then put a coat of Redgard(made by Custom Building Products, at Home Depot) over the backerboard. You can paint it on, its very easy. As far as the electrical box, if it was dry before then I would leave it as long as its not wrapping around any plumbing pipes.

Answer 6

Kerdi Board Lowes

Answer 7

You've answered your own Q in suggesting it's a MOOT point.

No offense meant at all, but a vapor barrier wouldn't have hurt, but now it's after the fact, and KNOWLEDGE is something we so often acquire AFTER the fact of needing it.

Hopefully you can assume that if the house didn't burn down with electric running adjaent to the shower/tub; it won't now. Hopefully too; you have no receptacles/ switches/ or lighting fixtures, directly in the shower; or path of any water.

If you proceed with the job in the proper manner; your larger worries may one day come from the roof/ siding/ leaking onto flooring. I hate it when I'm called to fix an issue where the tub in the second floor bathroom; suddenly ends up in the living room below. :)

Steven Wolf

Answer 8

unless its insulated behind there dont sweat it .also dont bother to tape and mud the seems .mud isnt water proof and wont allow tiles to stick properly.the mastik ,tile and, a good grout job forms a very waterproof seal.silicon seal the seams around the tub afterwards because the grout tends to break away from the tub(you have seen this i'm sure) the standard for backer in walls is 1/2 inch (onto studs) i assume you are putting your backer onto a previous wall and haven't gutted the wall .if you have bare studs i would double up the backer being sure to stagger the seams or else you might get "popped" tiles after a while. good luck

Answer 9

I spent some time in front of the computer for some tips on how to to install cement board and I found this article here very useful
http://www.miconstruguia.com/en/cement-board/
Hope this works for you too.

Answer 10

just put a coat of mud over your screws and tape and mud the joints , after it dries then your mastic or thin set , which ever you use to put your tile up will be water proof enough plus you will grout the tile so you wont have any probs