Durock over shpwer pan flange

Discussion in 'Shower & Bathtub Forum & Blog' started by Bob12345, Mar 23, 2009.

  1. Bob12345

    Bob12345 New Member

    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?
  2. Howard Emerson

    Howard Emerson I teach guitar:You call that a job?

    Huntington Station, NY
    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.

  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    New England
    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 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.).
  4. spinoza

    spinoza Philosophy Professor

    Vapor Barrier with Tile Ready.

    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.

  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    New England
    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...
  6. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    North Vancouver, BC
    Building Code Inspector is right.
    Builder is right about the gap.

    But without some kind of poly behind the Duruck you have a bad install planned here. I personally dislike Durock board and find it to be the lowest quality board out there today. I like much better the backer board from Wonderboard. WonderBoard Lite is my only recommendation in backer boards for 2014.

    Making the shower a topical waterproofed project will in my opinion make for a much safer and longer lasting shower build.
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