Insulation terms, Glossary


Air barrier
A layer of material resistant to air flow. A material which is applied in conjunction with a building component (such as a wall, ceiling or sill plate) to prevent the movement of air through that component.

Air barrier system
The assembly of components used in building construction to create a plane of air tightness throughout the building envelope and to control air leakage.

Baffles / Rafter Vents
Device to maintain a ventilation space between the insulation and roof deck, assuring air flow from the eave/soffit vents to ridge vent or other roof vents provided in attics and cathedral ceilings

Batts of Insulation
Pre-cut pieces of fiber glass or Rockwool mineral fibre insulation.

Blower Door
Diagnostic equipment consisting of a fan, removable panel and gauges, used to measure and locate air leaks.

Building Envelope
The external elements walls, floor, ceiling, roof, windows and doors of a building that encloses conditioned space; the building shell. 

Changing a substance from a vapor to a liquid state by removing the heat. The condensate shows up on surfaces as a film or drops of water.

 Energy Audit
A thorough assessment of a home’s 

thermal efficiency. 


Removal of existing insulation in attics 

Gable End Walls
The triangular end of an exterior wall above the eaves.

Gable Vents
A louver vent mounted in the top of the gable to allow the passage of air through the attic. 

Heat Flow
The rate at which heat moves from an area of higher temperature to an area of lower temperature. Btu/hr (W/hr). Heat flow is generally used to quantify the rate of total heat gain or heat loss of a system.

Heat Loss
Heat that is lost from a building through air leakage, conduction and radiation. To maintain a steady interior temperature, heat losses must be offset by a combination of heat gains and heat contributed by a heating system.

 Joist  (Rim or Headers)
Horizontal framing member set from wall to wall to support the floor or ceiling. 

 Loose-Fill Insulation or Cellulose
Particulate insulation, made from either fiber glass or cellulose, that is blown into a home using a motor and hose 

Fungal growths often resulting in deterioration of organic materials, especially under damp conditions. 

 Ridge Vents
A vent mounted along the entire ridge line of the roof to allow the passage of air through the attic or cathedral ceiling.  

Roof Vents
A louver or small dome mounted near the ridge of the roof to allow the passage of air through the attic.

Measure of resistance to heat flow. The ability of insulation to slow the transfer of heat is measured in R-values. The higher the R-value, the better the insulation material’s ability to resist the flow of heat through it.

 Thermal Barrier
A material applied over combustible plastic insulation, to slow the temperature rise of the plastic insulation during a fire so as to delay its involvement in the fire.  

Vapor Retarder/Barrier
A layer of moisture resistant material usually which controls moisture diffusion (defined as less than 1 perm) to prevent moisture build up in walls ceilings and floors.

Creates a positive flow of air that allows the house to "breathe" and helps prevent moisture build-up year-round.