underlayment
Isaac Kremer/ January 14, 2018/ / 0 comments
A material, as plywood or hardboard, laid over a subfloor to provide a smooth, even base for resilient flooring, carpet, or other nonstructural flooring; or a weather-resistant material, as roofing or felt, for covering and protecting a roof deck before shingles are applied. (Ching, 1995)