I had the drywallers install denshield tile backer and I am finally getting around to tiling. I noticed a problem while looking at it the other night. Most places I've seen say that the gap between the tub and the backer should be 1/4"-1/8". I'm not sure what happened here, but it looks to be about 1 1/8" to 1 1/4".

Can I still tile with this or do I have to cut out a section 1-2" above and install new denshield to the correct tub gap? I don't think the grout will stick correctly if there is a void behind it.

I will be contact the drywallers to tell them about this, however, the project was done around 2 months ago.



tub gap 1 tub gap 2


That big of a gap is a problem, especially the gap in the 2nd picture. It is standard practice to ensure that the waterproof membrane overlaps the vertical lip of the tub at the wall, so that any moisture that penetrates through the grout (yes, grout is porous whether or not you use grout sealer) will make its way down into the tub well rather than into the wall/stud bays.

This is a quote from the DensShield tech. sheet:

enter image description here

  • My thoughts exactly, thanks for the response. How would I go about fixing this? I'm thinking that I need to remove 1-2 feet of material above it and then measure and cut a new sheet so that it hangs down below the lip and leaves a 1/8" gap. Is this correct? – Dolph Sep 24 '16 at 21:44
  • Yes, that is how I would do it. Make sure you mortar and mesh tape the new seams created by cutting back the board. – Jimmy Fix-it Sep 25 '16 at 2:20
  • Ok thanks Jimmy, I'll have a go, thanks for the answer! – Dolph Sep 25 '16 at 3:08

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