A term used to describe installation in an unrestrained space or cavity, such as in an attic, where cellulose would be loose-blown over the attic floor.

The National Fire Protection Association

Particularly when referring to indoor air quality, is the slow release from a material, over a period of time, of a gas or chemical that was previously contained in or trapped in that material, either by design or use in the manufacturing process.

Over-issue or over-issued newsprint refers to newspapers that are printed but not purchased by consumers. For example, the Boston Globe may produce and distribute 1,000,000 newspapers on a given day, and have 250,000 returned unpurchased. These are over-issue newsprint and National Fiber purchases them in bulk for upcycling into cellulose insulation.

A measurement used to determine how fast water vapor is able to move through the pores of a material. A material with a perm rating of less than one, as defined by ASTM E-96, is commonly referred to as a vapor barrier.