Guide for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials

Description

Delamination, blistering, staining, mold growth, and otherproblems related to the installation and performance ofmoisture-sensitive flooring materials on concrete slabs arecommon. The problems include claims for total failure of theflooring system, construction-schedule delays caused by slowconcrete drying, and lawsuits involving indoor air quality. It iscurrently up to architects, engineers, floor covering installers,flooring and adhesive manufacturers, concrete contractors,and concrete producers to solve these problems.

The objective of this document is to reduce the potential for moisture-related problems in both slabs-on-ground and suspended slabs. It provides basic information on the concrete drying process, moisture behavior in concrete, testing for pH and moisture, and vapor retarders/barriers. Based on this information, recommendations for the design and construction of concrete slabs that will receive moisture-sensitive or pH-sensitive flooring materials or coatings are presented.

This document focuses on the behavior of moisture inconcrete slabs, and the effect of the concrete moisture condition on the performance of applied flooring materials. Reaching a desired moisture state, however, should not be the only acceptance criterion for a concrete slab that will be coated or covered. Floor flatness, surface texture, cracking, curling, structural capacity, jointing requirements, and the potential for the slab to stay acceptably dry should also be considered. The goal is installation of a flooring system—subgrade, subbase, vapor retarder/barrier, concrete slab (and possibly reinforcement), coating or flooring adhesive, and floorcovering—that satisfies performance requirements.