Unfaced Fiberglass Batt Insulation
This information reflects our best understanding of product composition in 2019.
Fiberglass batt insulation is a thermal insulating product with high thermal performance, moisture resistance, fire resistance, and is sound absorbent. Fiberglass insulation is fabricated using a molten glass batch consisting of raw materials (...
Fiberglass batt insulation is a thermal insulating product with high thermal performance, moisture resistance, fire resistance, and is sound absorbent. Fiberglass insulation is fabricated using a molten glass batch consisting of raw materials (sand, borates, soda ash, lime) and recycled glass cullet. The molten glass is spun into fibers and an atomized binder is applied as the fibers settle onto a conveyor to form batts which are then conveyed through an oven to cure the binder. Originally phenol-based formaldehyde binders were used, but fiberglass batt insulation manufacturers have now transitioned to formaldehyde-free binders. (Note that high density fiberglass insulation, outside the scope of this CP, may still use formaldehyde-based binders.) Fiberglass batts can be either unfaced or faced with a Kraft paper, foil, or polyethylene film vapor retarder. This CP describes unfaced fiberglass batt insulation (distinct from faced fiberglass batt). Unfaced fiberglass batt insulation is installed by placing the batts into the wall cavity, allowing friction to hold the insulation in place. Frequently the insulation is then covered with a separate vapor retarder (e.g. polyethylene film), which is placed over and stapled to the studs before installing gypsum board. Moisture-resistant gypsum board is generally used without a separate vapor retarder for unfaced fiberglass batt in places such as bathrooms to allow moisture to escape. This CP excludes any vapor retarders that may be used with unfaced fiberglass batt insulation.
A historical version of this CP is available here: https://pharos.habitablefuture.org/common-products/2202610