Tile Shower Stall waterproofing advice needed

[John Lorentz]

OK, here’s the situation: My wife and I are American expats living in former Soviet Central Asia. We recently bought a soviet era apartment and we are in the middle of a top-to-bottom remodel. Most construction here is concrete walls, so they aren’t used to using drywall and wood for walls.

My wife and I opted to install a plastic shower stall base and tile the three walls around it. The wall that the shower head and knobs are on are concrete and blocks while the two walls receiving most of the spray are blue board.

Problem: I need to waterproof the blue board before the tile goes on.

Facts:
– Concrete board is not available here.
– blue board is the closest I’m going to be able to get.
– In the states I think I would use something like redgard but that also isn’t available here.
– Thinset motar is what they would usually use here.

Question:
– Can anything be added to the thinset to make it a waterproof membrane or at least help it to be more water resistant? If so, what is the general name of the material (no name brands since those won’t be available here).
– There are several screws and corner seams, what do I need to fill these with to improve the water resistance or even make it waterproof?

[plumberincanterburyParticipant]

You could try PVA

Plumber in Canterbury

[manmohanpvcParticipant]

I think to you should contact Plastic Pipe experts.

[nicktheplumberParticipant]

As for the concrete block wall, you can apply thinset to that to smooth it out and affix the ceramic tile and then grout the tile seams. As regards the other shower walls, given the lack of cement board or other US approved tile backing materials, I would recommend doing it the “old way.” The old way would be to frame up these walls with locally available framing materials (lumber or steel studs) to which you apply a membrane (tar paper would be OK) and then metal lath. Then you apply a two or three coat cement surface (essentially stucco). When this dries sufficiently, you apply thinset and attach your ceramic tiles in the usual manner.

This requires a bit of work compared to using cement board backing, but it is just as waterproof as cement board and is far better than using supposedly waterproof sheetrock.

That is the way I built my first shower back in 1973, and I’ve built a few others that way since then.   

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