A.Michael Byrne, a tilesetter and industry consultant from Los Olivos, Calif., responds: First, there are several mortar bed installation methods that require no reinforcing. These are typically for floors where you're putting a bonded mortar bed over an intact slab-on-grade. These methods, which are based on ANSI A108 specification standards, are described and illustrated in the Handbook for Ceramic Tile Installation, available from the Tile Council of America (864/646-8453, www.tileusa.com).
For thick mortar bed installations over wood floors (left), ANSI specs call for wire fabric reinforcing and a cleavage membrane between the subfloor and the mortar. For thin mortar beds (right), use expanded metal lath nailed or stapled to the subfloor.
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