Insulation glossary

AmountTotal amount of either square footage (SF) or lineal footage (LF) required to complete the project
ASJ+ - all service jacketAluminum foil, reinforced with a glass scrim bonded to a kraft paper interleaving with an outer film layer leaving no paper exposed.
BTU (British Thermal Unit)Heat required to raise temperature of one pound of water by one degree; around the same amount of energy released by one wooden match.
Cavity depthDepth of either wood or metal framing components used to determine the amount of insulation that can be installed within a given cavity.
Class I vapor retarder0.1 perm or less
Class II vapor retarder1.0 perm or less
Class III vapor retarder10 perm or less
Closed blowA netted application of loosefill insulation where the net holds the insulation in place during installation and remains in place for the life of the system
C-valueHeat flow property, conductance, of a product at a given thickness. The lower the C, the better the insulator.
DensityAmount of solid material, expressed in pounds per cubic foot (PCF).
EmittanceUsed for measuring the resistance of a material to radiative heat transfer. Typical values are 0.02 - 1, with the lower values being better radiant barriers.
FacerCovering adhered to base glass mineral wool material. Used primarily as a vapor retarder, and secondarily for cleanability, color, or integral structural components.
FSK- foil scrim kraftLaminate composed of thin layer of aluminum foil, glass fiber reinforcing scrim, and kraft paper.
Installed R-value (Duct wrap)Laminate composed of thin layer of aluminum foil, glass fiber reinforcing scrim, and kraft paper.
K-valueHeat flow thickness of a homogeneous material. The lower the k, the better the insulator.
Open blowLoosefill insulation with integral adhesive, directly applied to the wall cavity without need for additional netting
PermUnit of permeance of water vapor transmission where a difference in pressure exists on either side of a material or membrane (US perm = 1 grain of water vapor per hour, per square foot, per inch of mercury).
Pipe sizePipe sizes are expressed in imperial units for either iron pipe (Iron Pipe Size - IPS) or copper tube size (CTS)
PSK- poly scrim kraftString reinforced polyethylene kraft facing.
R-valueAbility of material, or building section to retard heat flow. The higher the R, the better the insulator.
U-valueHeat flow property of an entire building section. The lower the U, the better the insulating value.
Vapor retarderThin layer of material varying in permeance, included in building construction to slow moisture migration. Vapor retarders are split into three classes.