Subfloors & Underlayments

New and existing concrete subfloors must meet the requirements of the latest edition of ASTM F 710, “Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring,” available from the American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428; 610/832-9500; http://www.astm.org.

Note: Regardless of the type of concrete or other cement-like material used as a base for resilient flooring, in the event of underlayment failure, the responsibility for warranties and/or performance guarantees rests with the concrete or cement-like material manufacturer and not with the manufacturer of resilient flooring.

On-Grade Concrete Floors

1. The slab must be of good quality, standard density concrete with low water/cement ratios consistent with placing and finishing requirements, having a maximum slump of 4″, a minimum compressive strength of 3000 psi, and following the recommendations of ACI Standard 302.1R for Class 2 or Class 4 floors and the Portland Cement Association’s recommendations for slabs on ground
2. The concrete slab must be dry, clean, smooth, structurally sound and free of foreign materials that might prevent adhesive bond as described in ASTM F 710, “Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring”.
3. The concrete slab must be protected from ground moisture with an effective and intact vapor retarder that conforms to the requirements of ASTM E 1745, “Standard Specification for Water Vapor Retarders Used in Contact with Soil or Granular Fill Under Concrete Slabs.”
4. The concrete slab must be placed directly on the vapor retarder.
5. The concrete must be wet cured with a moisture-retaining curing cover. Do not use spray-on curing compounds because these reduce the drying rate of concrete and can interfere with adhesive bond.
6. Before installation of the finished flooring, moisture, alkali and bond testing must be conducted.
   1. Moisture testing must be done according to ASTM F 2170, “Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes” (preferred method) or in accordance with ASTM F 1869, “Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride.” See section on Moisture Testing for more details.
   2. The surface of the concrete must have a pH of 9 or less.
   3. Bond testing must be run to determine compatibility of the adhesives to the concrete slab.