Waterproof membrane for concrete substrate
I will be tiling a shower/bathroom house at a campground this summer. The floor substrate will be concrete and the walls will be masonry block. The architect did not specify any waterproof membrane for the entire job. I am wondering if this will be okay since it’s all concrete. Should I suggest some kind of waterproofing/crack-isolation membrane? If so, could you refer me to the place in the TCNA Handbook that explains this?
Thanks for contacting the NTCA. We encourage everyone to use industry-recognized methods found in the Tile Council of North America Handbook for Ceramic, Glass and Stone Tile Installation, and ANSI. There are a variety of shower methods that would work with the installation type you described (See methods B421 and B422 TCNA Handbook). All incorporate waterproofing that meets ANSI A118.10. standards.
Having the appropriate slope and drain connection is crucial in every shower design. Water can pass through grout, stone and many tiles, so installations need waterproofing beneath the tile. Although the subsurface is block and concrete that may not be harmed by water, water can pass through these surfaces and get into areas where it is not desired. When waterproofing is not used and water soaks the block or concrete, those areas can continually remain wet, discoloring stone tiles and grout. A wet subsurface also creates a source of moisture that can encourage mold growth when organic materials like soaps are left behind.
– Robb Roderick,
NTCA Technical Trainer