Waterproofing with redgrave or not!?

shorteared

I have had a couple of people from this site tell me to use regard in my newly constructed basement shower. Currently I have cement backer board up and a cement shower base with a rubber membrane ready for tile. My questions...

1. Do I NEED to put a waterproof membrane like redgard on the walls. Can I simply silicone the joints and screws?

2. If I use the redgard will this create another vapor barrier on the wall ( I have a vapor barrier in the wall to the outside already)?

All of your thoughts are welcome!

oh'mike

Red guard will insure that the water will stay in the shower and not soak into the board.

I suggest that you use it---it is not a great idea to have a double vapor barrier--bit that is better than relying on a plastic sheet that is full of holes from the rock screws.

What ever you choose to do---do not use silicone on the seams anf joint of the durrock---those should be covered with tilers mesh and filled with thinset as you tile--or (if you use Red Guard) filled lightly before the red guard is applied.

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joecaption

Not sure how you came up with the silicone idea.
The seams get taped with webbed tile tape that's bedded with thin set as well as over the screw heads.

Bonzai

1. As regards RedGuard... By minimum code (which depends where you are) not necessarily. By common sense and modern building methods, yes absolutely. Cement backer board is not waterproof ie. it is porous.

2. The poly vapour barrier between the cement board and the studs is to keep moisture from the framing/insulation. The RedGuard on the cement board (tile side) is so that moisture that seeps through the grout or tile (if a porous tile) does not go any further and damage the cement board. You will only get condensation issues if 2 vapour barriers are next to each other with nothing but air between.

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TarheelTerp

RedGard is GoodStuff
It'll even work on shower floors made of wood:

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shorteared

You guys rock, thank you. You have convinced me. I do have another question about the ceiling of my shower. I do not plan on tiling it. Should I use blue drywall or cement board? Can I put RedGaurd on drywall? Your thoughts are much appreciated.

Bonzai

In terms of the ceiling of the shower, normally the whole bathroom ceiling is just regular drywall with a good bathroom paint. If your shower is more enclosed and not close to the bathroom fan then it certainly doesn't hurt to use cement board ... Bear in mind though that it has a rough surface and will need skimming with mud to get a smooth finish. I would only ever waterproof the ceiling if I was building a steam shower with tiled ceiling.

Technically you can RedGard over regular drywall ... We do this when installing a kitchen backsplash rather than just tiling on the drywall directly. Think how much steam there is in a kitchen ;-)

FYI: there is a product by Mapei called Mapei HPG which is very similar to RedGard except it is blue. I used to use RedGard but found that we get better coverage with the Mapei product and it is also about 25% cheaper.

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