2024-25_NTCA_Reference_Manual_dig_dwnld

Self-Adhered Crack-Isolation and Sound Control Membranes

NARROW GROUT JOINTS – The minimum grout requirements for ceramic tile is 1/8 in. (3 mm) per ANSI A108.02 and for natural stone the minimum grout joint is 1/16 in. (2 mm) per Natural Stone Institute (NSI). It is even more critical when installing tile over membrane. These conditions apply regardless of whether membrane is used.

Problem

Cause

Cure

Grout is cracked or pushed out of joints; joint may be narrower than original installation; tile edges, especially soft stone tile, may be chipped.

Narrow grout joints provide no buffer to inward movement of the tile assembly when tile is installed over a flexible membrane; excessive inward movement often results from one of the above described errors.

Install joints per ANSI A108.02 when installing large tile; also follow above described guidelines to reduce potential for tile assembly movement found in TCNA Handbook method EJ171.

NTCA Reference Manual | 2024 / 2025

Chapter 4 | Membranes

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