Underlayments

Part of speech: noun

Definitions

1. A layer placed beneath a finished surface to provide support and insulation
2. Materials installed under floors or roofing to enhance comfort, soundproofing, or moisture control
3. Structural components laid under coverings to improve durability and performance of the surface above

Etymology: "Underlayments" is the plural of "underlayment," a noun formed from the verb "underlay" plus the suffix "-ment." The verb "underlay" is itself a compound of "under" and "lay," meaning to place something beneath another surface, so the noun names the material that gets laid down before a finished floor or roof covering goes on top. The suffix "-ment" is an old and productive English ending that turns a verb into a noun for the act or result of the action, as in "placement" or "pavement." Here it shifts the sense from the action of laying something underneath to the thing itself, the layer of felt, foam, membrane or board that sits between the subfloor or roof deck and the surface above.

Synonyms: substrates, foundations, bases