What is the association’s recommendation as far as a trowel size to use when installing an 18”x18”x3/8” ceramic tile? Do I need to back-butter the tile? I am installing on 1/4” Durock placed over 3/4” plywood subfloor over radiant heat.
For an 18”x18” tile, you should use a medium-bed thin-set mortar. You will probably need a 5/8”x3/4” loop-notch trowel to get the proper 80% coverage for interior dry areas. Back-buttering is always a good idea to improve coverage.
– Michael Whistler, NTCA Symposium presenter
We need an installation method for installing Daltile 2”x2” mosaic tile in a roll-in shower room. The architect has had us use a cleavage membrane (#15 felt with wire lath) at all floor areas where we’re using mud. The building floors are a concrete plank. There is also a drain outside of the shower area in the space where the toilet and sink are. The rooms outside the shower will get wood flooring with wood sleepers below (approximately 2” total). There is no need for a saddle between the shower and the toilet and sink area. The high points should be around the perimeter of both areas, and most importantly at the entry into the shower area, which acts as the high point for both areas. We would use waterproofing. What do you suggest?
To follow is a drawing that shows common installation procedures for curb-less shower systems to retrofit an existing shower with ADA-approved wheelchair accessibility. No saddle or threshold that a wheelchari need negotiate will have a change in elevation of more than 1/2”, and no two elevations shall occur closer than 5’.
This can be used with a cleavage membrane along with reinforcing wire but will increase the mud bed thickness from 1/2” to at least 3/4” at the thinnest locations for residential; 1-1/4” for commercial. This may require raising the floor outside the shower 1/4” to 3/8” to meet the wheelchair accessibility recommendations. This is a common practice but is not yet available in the TCNA Handbook. The NTCA Methods and Standards Committee is currently working on submissions related to barrier-free and curbless showers for the Handbook.
– Gerald Sloan, NTCA training director