1.1 This guide outlines the types of wood underlayment products commonly available for use under resilient flooring. 1.2 This guide points out the subfloor factors that shall be controlled in preparing underlayment as a base for resilient flooring. 1.3 This guide does not cover the structural adequacy of the subfloor or combination subfloor-underlayment which is governed by applicable regulatory agencies, nor does it apply to wood underlayment over concrete floors. 1.4 This guide does not supersede, in any manner, the underlayment manufacturers or the resilient flooring manufacturers instructions. Not all underlayment products are approved by all resilient flooring manufacturers. 1.5 This guide does not attempt to cover details of underlayment installation. Follow the detailed instructions of the flooring or underlayment manufacturers or both. Where conflicting instructions exist, consult the manufacturers warranty coverage.