The word Batt is short for Batting, which refers to the fluffy material in between a quilt. To bring this term into architecture, a batt is any section of rolled material that can be applied in between two materials or assemblies. It is most commonly referred to in [[ThermalInsulation thermal insulation]] as batts of fiberglass insulation.

Batt insulation is cheap, but has a lower [[RValue r-value]] than [[RigidInsulation rigid insulation]].