Waterproofing Questions

[TAD1951]

1.I read Dukedog's thread about Redguard and was wondering if this is standard procedure over cbu's? I am not sure I saw it mentioned in "Tile Your World". Would you still use poly sheets behind the cbu with Redguard? I suppose Redguard would be applied on the mortar bed also?

2. Has anybody used silicone caulk in the cbu joints instead of mesh tape and thinset? Would this work on outside corners? I have read this prevents humps from showing thru on the tile.
Thanks.

[ddmoit]

1.) I wouldn't call RedGard standard procedure. It's just one way of doing it. You can use poly sheets or roofing felt behind the CBU. The important thing is to pick one AND ONLY one barrier and go with it. Two barriers is asking for trouble in the form of a moisture sandwich.

2.) Silicone caulk will not provide the structural support of taping the joints with alkali resistant mesh. Silicone is good for waterproofing, but CBU isn't waterproof to begin with. CBU is not damaged by water, but it does not serve as a water barrier. To avoid the "speed bumps", just put the mesh on as you are setting your tiles. I've been doing this and it works just fine.

[TAD1951]

Thanks Dan, that sounds lika a plan.