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Building Science

Insulating the Attic/ Roof

Homes lose a lot of energy when warm air inside rises and leaks into attic space. Adding insulation to reduce energy loss can make sense, especially when it can address air leaks and provide an air-seal.

What's the problem?
  • Conventional insulation, such as fiberglass and cellulose, doesn't meet air barrier standards (based on air permeability testing, ASTM E 283) so it doesn't do a good job of stopping air flow/ leaks and can sag or settle over time 
  • The cost of adding insulation thickness (R-value) outweighs the savings after a certain level
  • Rafters in cathedral or vaulted ceilings may have limited space for insulation
What can you do?
  •  Seal all areas where air can leak from the home, including electrical entries (subject to local building code standards)
  • Seal and insulate attic access doors
  • Consider an open-cell spray foam insulation to create an air barrier against air leaks and achieve optimal R-value in one step. Spray foam insulation can also be a solution to challenges like cathedral ceilings

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We had our barn insulated with Icynene and we had a special visit from the local gas utility because the fuel consumption was so low!
Bill Walker, Lethbridge