Which of the following is a common material used with Vapour Barriers?

• A. Foamglass
• B. Concrete
• C. Wood
• D. Aluminum

Answer: (A)

Vapour barriers are meant to limit moisture moving through building assemblies. You want a material that itself stops water vapor effectively while also providing good insulation. Foamglass is a closed‑cell cellular glass insulation made from recycled glass. Its cells are impermeable to air and water, giving it very low vapor permeability and excellent dimensional stability. That combination means it helps keep moisture out of the assembly without absorbing moisture or sagging, making it a common companion to vapour barrier systems, especially in foundations and damp environments.

Wood, being porous, readily allows water vapor to diffuse through. Concrete can be dense, but its pores can still transmit moisture under certain conditions and it can crack, creating pathways for vapor. Aluminum by itself isn’t typically used as the insulation backing in standard practice, and while foil can act as a vapor barrier, foamglass offers a more practical, integrated solution in many assemblies.