Is RedGard or similar a must for shower walls?

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yan

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We had a leak on our shower pan and long story short - we are in the process of getting the shower pan replaced and discovered it did not waterproofing material at all. The grout failed, and they also used dry wall on the curb instead of cement board which was all rotten!

We are almost sure there isn't any waterproofing done behind the tiled wall also. (they did use cement board for the walls) So far we don't have any problems with the walls but I wonder if we'd need to rip everything out to redo the entire shower? Our contractor seems to think it's fine to leave it as is and there's no need to re-do the walls. I'm a bit paranoid there would be problems but he says vertical walls are fine. Thoughts?
 

Jadnashua

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Industry guidelines call for a moisture barrier behind cement board (cbu) on the walls OR a waterproof membrane on the tile side.

FWIW, neither tile nor grout is considered the waterproofing in a shower. The tile is a decorative wear surface. The shower should not be damaged by moisture even before the tile and grout is added.

The liner in a shower is considered the waterproofing on the pan. That layer MUST be sloped to the drain. The top layer is sloped because the bottom one is. So, it's a presloped mud bed, liner, setting bed, then thinset and tile. THere are LOTS of showers built with the liner flat on the floor...that tends to let moisture accumulate underneath the tile. It can get pretty nasty under there when that happens, but it takes awhile. With HI's typical humidity levels, it may happen quicker.

You CANNOT use cement board on the curb, as there's no way to hold it in place without putting holes in the liner. Code says NO penetrations of the liner within 2" ABOVE the TOP of the curb.

A home in HI may not have a vapor barrier behind the siding, so any moisture that might get through the cbu probably has a chance to dry towards the outside...but, industry guidelines still call for protecting them. That is often done with either roofing felt on the studs, or a plastic sheet. Alternatively, you can waterproof the walls. If you're not redoing the whole shower (it's hard to get a new pan in there properly without removing at least the tile below the curb so that a new liner can be put in). Generally, it's easier to just replace the shower.
 

DIYorBust

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Shower with cement backer and tile, but no waterproofing were once common. Even maybe 10-15 years ago. And they more or less work, except when they don't. So if you have this condition and you have no leaks, I would say let sleeping dogs lie. The tile will keep the water out mostly. But if you are considering redoing it, definitely use a waterproofshower.
 
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