vapor barrier

noun

, Building Trades.

1. a layer of material, as plastic film or foil, used to protect installed insulation by retarding the transmission of moisture from the interior environment.

Word History and Origins

Origin of vapor barrier¹

First recorded in 1940–45

Example Sentences

The downside comes when that promise turns out to be false — if the buyer moves in only to find out that the roof needs replacing or the bathroom has no vapor barrier and mold is growing.

From Washington Post

LNG terminals are typically designed with vapor barriers at the perimeters.

From Washington Post