Natural stone is unforgiving of subfloor movement. Before installation, the subfloor must be verified for deflection, as the weight and rigidity of stone cause tiles to crack if the substrate flexes. Industry standards often specify a deflection limit of L/720. The surface must be perfectly level; any dips or rises must be addressed with a self-leveling compound or cementitious patch. Furthermore, the subfloor must be clean, dry, and properly prepared with a crack-isolation membrane if there is a risk of substrate movement. These steps ensure the stone remains stable, preventing mortar bond failure or tile fractures over the lifetime of the floor.
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What are the structural requirements for a subfloor before installing stone tile?
Stone tile requires a subfloor that is exceptionally rigid, level, and structurally sound to prevent cracking. Deflection must be kept to a minimum, typically L/720, and the subfloor must be free of contaminants, properly cured, and protected by appropriate moisture barriers.