Below-Grade Concrete

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;

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.

Below-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 the current edition of ASTM F710, 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 the current edition of ASTM E1745, “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 the adhesive bond.
  • Before installing the finished flooring, moisture, alkali and bond testing must be conducted.
    • Moisture testing must be performed in accordance with the current edition of ASTM F2170 “Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes” (preferred method) or in accordance with the current edition of ASTM F1869, “Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride.” See the section on Moisture Testing for more details.
    • Unless otherwise indicated in Section E-10 Moisture Testing,the surface of the concrete must have a pH of 9 or less when tested according to the method described in the current edition of ASTM F710.
    • Bond testing must be performed to determine compatibility of the adhesives to the concrete slab.
Updated on October 26, 2022