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
- 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
- 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”.
- 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.”
- The concrete slab must be placed directly on the vapor retarder.
- 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.
- Before installation of the finished flooring, moisture, alkali and bond testing must be conducted.
- 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.
- The surface of the concrete must have a pH of 9 or less.
- Bond testing must be run to determine compatibility of the adhesives to the concrete slab.