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Bob12345
03-23-2009, 10:42 AM
Should the Durock overlap the shower pan flange?
Contracter say doesn't need to, actually prefers a gap
between bottom of durock and top of shower pan flange.

Building code inspector (who doesn't inspect this) said
tile cement filling in the gap would be OK.

Currently there's about 1/2 inch gap. Should I worry about this?

Is there no set "code" or correct way to do this?

Howard Emerson
03-23-2009, 10:48 AM
Should the Durock overlap the shower pan flange?
Contracter say doesn't need to, actually prefers a gap
between bottom of durock and top of shower pan flange.

Building code inspector (who doesn't inspect this) said
tile cement filling in the gap would be OK.

Currently there's about 1/2 inch gap. Should I worry about this?

Is there no set "code" or correct way to do this?

Bob,
I don't know about code, but I will say that the most important thing is that the Durock be 'proud' (sticking further inside)of the tile flange. The 1/2" gap is not wonderful, but when filled properly it should not be a problem.

HE

jadnashua
03-23-2009, 01:31 PM
What's probably more important is that the vapor barrier laps over the flange. The size of the tile is one consideration about how much of a gap can be used. What you don't want is to have the cbu bow out over the flange. The way around that is to either recess (notch) the studs to allow the flange to be flush with the rest of the stud, or shim the studs so it can go over. You want more than 1/2 of the tile to be supported on the cbu. Note, all changes of plane should be caulked, not grouted and make sure that the cbu joints and corners are taped with the proper alkali resistant mesh tape. This can be done while tiling, otherwise you may end up with speed bumps. If there is no vapor barrier behind the cbu, then you have a problem with the gap since you then couldn't use a surface applied one to compensate. Check out www.johnbridge.com (http://www.johnbridge.com) for tiling help. Cement directly on wood is never a good idea. While the cbu isn't affected by moisture, it will wick it. You need to prevent that from coming in contact with mold food (i.e., wood, paper, etc.).

spinoza
03-29-2009, 04:14 PM
Your response to Bob raises a question for me. I am now convinced that I should use a vapor barrier. But how to do this with a tile ready pan?

If I use the ready flash on the tile ready pan, and then rest the durock (cement board) over the ready flash, it seems I then have no way to have the vapor barrier drain onto the pan.

But maybe this is the solution: Do you think it is a good idea to lay a bead of caulk on the ready flash lip and then bring the vapor barrier (plastic sheet) right to this caulked lip. Then I could rest the cement board on top of the plastic.

Also, I am not sure how water that gets under the shower floor tiles can drain in the ready tile pan if the drain does not have weep holes? Is this not an issue? With a mortar pan, the water reaches the plastic barrier and drains.

Spinoza

jadnashua
03-30-2009, 06:14 AM
Depending on the design, the lip of the pan may be designed to have tile come down below it. If so, then the vapor barrier can just be brought down over that lip, then the tile would cover it.

The drain for that pan may allow moisture to wick into the drain. You won't get much moisture beneath the tile, but if the pan is waterproof, since not much would accumulate like in say a 1" thick mortar bed, it should dry out rather than accumulating (which would need the weep holes). You just have to hope the manufacturer did their engineering...