4.1 This practice provides minimum recommendations for the installation of thick poured gypsum concrete floor underlayments suitable to receive resilient floor coverings. This practice establishes the proper preparation, installation and quality control for thick poured gypsum concrete floor underlayments.

4.2 Actual requirements for thick poured gypsum concrete underlayments are generally included as part of project plans or specifications and may vary from the recommendations set forth in this practice. Project plans or specifications, or both, shall supersede the recommendations set forth in this practice.

1.1 This practice covers the installation and preparation of the thick poured gypsum concrete underlayments over wood structural panel subfloors in commercial structures or over concrete floors in commercial structures and the preparation of the thick poured gypsum concrete underlayment surface prior to the installation of resilient flooring in commercial buildings.

1.2 This practice covers the factors that are required to be controlled while installing thick poured gypsum concrete underlayment as a base for resilient flooring.

1.3 This practice does not cover the structural adequacy of the wood structural panel subfloor or concrete subfloor. The structural integrity of assemblies is governed by local building codes.

1.4 This practice does not supersede in any manner the thick poured gypsum concrete underlayment manufacturers, adhesive manufacturer’s or resilient flooring manufacturer’s written instructions. Consult the individual manufacturer for specific recommendations.

1.5 Thick poured gypsum concrete underlayments are not suitable for use on concrete slabs on ground due to potential moisture problems arising from moisture intrusion, unless an adequate vapor retarder or vapor barrier is present directly beneath the concrete subfloor.

1.6 The values stated in inch-pound units are to be regarded as standard. The values stated in parentheses are approximate mathematical conversions to SI units, which are provided for information only.

1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.