Concrete slab configuration is critical to the success of a new synthetic floor installation. Placing a below-slab vapor barrier directly beneath the concrete slab is proper and typical.
Placing any type of fill material between the below-slab vapor barrier and the concrete slab normally causes moisture-related problems with synthetic systems. By placing sand between the vapor barrier and the slab, a flatter concrete slab with less initial curling can be produced. However, this new configuration allows the sand to act like a sponge -- trapping moisture within the sand layer during the concrete pour. Over time, trapped moisture will frequently migrate up through the concrete slab and cause moisture-related difficulties with the synthetic floor’s adhesion to the slab.
The WSFI states that to provide guidelines or specifications as it relates to below-slab vapor barrier, please consult the synthetic floor supplier or any appropriate industry sources such as ASTM E1745 and/or the American Concrete Institute (ACI).
For more information regarding variations to WSFI’s recommended concrete slab configuration, please contact WSFI’s Technical Director at 888-480-9138 or email
Disclaimer: The MFMA provides general information to architects, specifiers and consumers. The MFMA, its members, officers and agents disclaim any responsibility whatsoever for the accuracy or applicability of these guidelines under all circumstances and conditions.
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