2024-25_NTCA_Reference_Manual_dig_dwnld

Underlayment Cracks and Their Treatment – Letter

LETTER FOR THE TILE CONTRACTOR

Date

Name Address City, State Zip

RE: Cracks and their treatment

• The architect, builder or design professional must specify movement joints and show location and details on drawings. • It is not the intent of the TCNA Handbook for Ceramic, Glass, and Stone Tile Installation ( TCNA Handbook ) or ANSI Standards and Specifications for the Installation of Ceramic Tile to make movement joint recommendations for a specific project. • It is particularly important when dealing with a cracked substrate that expansion joints are properly located and filled with a suitable sealant, or prefabricated expansion joint. All joints; expansion, control, construction, cold, saw-cut, isolation, contraction, and seismic, in the substrate should continue through the tile installation, including such joints at vertical surfaces. If this is not desirable or possible, consult with the manufacturers involved, select only those products they recommend, and carefully follow their installation instructions. Require their written warranties for installations that are not specifically and fully covered by existing industry methods and specifications. • If a crack-isolation membrane is specified over saw-cut joints that are intended for relocation of movement joints complying with TCNA Handbook Method EJ171, the tile contractor shall not be responsible for cracking in grout joints or tile over such joints when installed correctly. Relocation of movement joints is especially not recommended where tile patterns are installed diagonally across saw-cut joints because of their reduced performance. Use of saw-cut joints as relocation of movement joints is especially not recommended. Where tile patterns are installed diagonally across saw-cut joints the performance of existing movement joints is reduced. • Careful examination and evaluation of your project to determine the type, size and extent of cracks to be treated are essential for selection of a trowel applied, liquid and/or sheet membrane to minimize crack propagation from the substrate. • Ascertain that the manufacturer’s warranty adequately and specifically states what it covers for your project. Some warranties cover replacement of their product only and not the entire failed installation of tile, stone, setting materials and labor.

Name and Title Company

This document is compiled by the NTCA Technical Committee and published by National Tile Contractors Association, Inc. • P. O. Box 13629 • Jackson, MS 39236 U.S.A. The disclaimer on page 1 and the introductory comments contained in the complete Reference Manual are applicable to copied or excerpted parts.

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NTCA Reference Manual | 2024 / 2025

Chapter 3 | Backerboards and Underlayments