underlayment

/ˈʌndərˌleɪmənt/
noun
  1. A layer of material installed beneath a finished floor or roof to provide support, moisture protection, or sound insulation.
    • This foam underlayment helps reduce noise between floors in an apartment building.
    • The contractor installed a plywood underlayment before laying the hardwood floor.
    • A waterproof underlayment is essential under tile in a bathroom to prevent leaks.
Synonyms
What does "underlayment" mean? | whatsthatwordmean | whatsthatwordmean