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lilia07

Bathroom floor flexing, broken tiles

Lilia07
9 years ago

Hello all. We just finished our bathroom renovation - less than 3 weeks and we have noticed the following problems: 1. the floor is flexing and all the grout on the joint lines (wall and floor) got cracked. My husband regrouted the lines, and the cracks reappeared after a day.The floor also makes a crunchy sound in one spot. The floor construction was as follows: plywood (not sure what was the thickness, but we have a piece left and it seems pretty thin and easily flexible). Blue board. Thinset. Tile.
2. We did a porcelain basketweave on the floor, which came on a 12x12 (I believe) mesh. I noticed at least 5 white little pieces that were snapped right in the middle in different locations of the floor (not sure if it's due to flexing, but it basically was like this on day 1, when i started cleaning the floor, so it was not caused by us dropping anything).
3. the grout came out in different areas of the floor (again, not sure if it was because of flexing or something else).
The contractor came to see and he said that it looks like we need more reinforcement, so he suggested to open up a ceiling below the bathroom (bathroom on the 2nd floor) and reinforce it from inside (we are going to do the renovation on the 1st floor anyways, so we are ok with opening the ceiling). He also said he will bring some other grout and regrout the floor to get rid of the cracks.
I wanted to see whether the floor was constructed adquately? Also, although the broken tiles are not easily noticeable, they are there and it makes me upset knowing they are broken. Does the contractor's approach seem right? Or should we ask him to redo the floors and retile them? Appreciate your feedback in advance!

Comments (6)

  • weedyacres
    9 years ago

    What is the span and the spacing of the floor joists? Google "deflectolator" (GW doesn't allow links) and plug those numbers in to see if the floor framing is sufficient to support tile.

    Then review your floor construction:
    Plywood: You need 3/4" either plywood or OSB on top of the floor joists. Verify how thick it is.
    Blueboard: Are you sure? Like drywall? This should be cement board. There should be thinset between the plywood and cement board, and it should be screwed in every 8". If your contractor really used blueboard, the job needs to be torn out and redone.
    Thinset+tile: at least this is right.

    This sounds like a major fail to me. Report back on the details above and we can help further.

  • Lilia07
    Original Author
    9 years ago

    Plywood was 3/4", and then Durock cement board (apologies for the confusion, blue board was on the walls)

  • weedyacres
    9 years ago

    OK, glad it wasn't blueboard. :-)

    Did you check on joist spacing and deflection?

    And was the Durock installed with thinset below and screwed every 8"?

  • Fori
    9 years ago

    As far as the grout cracking between floor and walls, it's a minor problem compared to the flexing--it'll always crack there which is why it's not supposed to be grouted at all. It should be caulked.

  • MongoCT
    9 years ago

    Weedy gave you pretty good advice.

    A typical "fail" is that the cement board is simply nailed or screwed down over plywood. As Weedy mentioned, the cement board should be bedded in thinset, then fastened to the plywood with nails or screws.

    The bed of thinset simply acts as a void filler between the cement board and the plywood. It prevent micro up and down movement of the cement board. That micro movement can result in popped tiles and cracked grout.

    With a basketweave, it's be common for the grout to crack and pop out of the joints. But for the individual pieces to crack? Being small, they can usually accommodate some movement in the substrate.

    I'd take a close look and see if they are indeed cracked, or if perhaps grout got stuck in any veining or fissure lines in the tiles. If the tiles are indeed cracked, that's a problem.

    It's very difficult to effectively reinforce a floor from below. Floors can flex in one of two ways. The joists can be undersized, so you're getting flex along the length of the joist. Or the plywood can be undersized, so you're getting flex in the plywood between the joists. IF the joists are properly sized, the plywood sufloor should have ben 3/4" thick tongue and groove plywood. Covered with 1/2" thick cement board, thinsetted and fastened in accordance with the manufacturer's installation instructions.

    As far as the grout in the wall/floor joints all cracking, as fori wrote, those corner joints should be caulked and not grouted. Caulk can flex with movement between different planes. Grout, being rigid, will crack instead of flex.

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