We use blown-in spray foam as our main insulating material for our walls. Spray foam is composed of a polyurethane base, and can come in two different varieties - 1/2 lb, which is an open-cell foam, and 2 lb, which is a closed cell foam. They both have different properties and serve a different purpose.
Open-cell 1/2 lb foam is low density, spongy material that can be compressed under pressure. The blowing process initiates a foaming process that fills the material with a tonne of mini air-pockets - allowing the material to expand 100 times its original size. The material is air-tight and behaves as both the insulating material and the air barrier for the building envelope. It is still vapour permeable however, so it is still necessary to install a vapour barrier. The R-value for open-cell spray foam is between 3.6-3.8/inch. The product can be installed in temperatures down to -20? C, making it advantageous for winter builds. The foam is water blown in, so its use does not contribute to greenhouse gas emissions. We use 1/2 pound spray foam in all of our wall cavities.
Closed-cell 2 lb foam is a medium density foam that is quite hard to the touch. It behaves as an air barrier due to its low air permeability and also behaves as a vapour barrier. The R-value for closed-cell spray foam is 6.5/inch. The product should not be installed below 0? C, although there are some formulas that are tolerant to -10? C. The foam is gas propelled like that of an aerosol container, so there is a mild contribution to greenhouse gas emissions. We use closed cell foam in basements, as its high R-value and air/vapour seal allow the basement to stay warm and dry.
For a 2x8” wall, the R-value is 28; 2x10” is R35.For a super insulated wall we attach a 1” thick foil faced foam to the interior wall. This provides added insulation and an R-value of 7 to the wall, while sustaining a vapour barrier.
We use 2 1/2 inch sheets of rigid foam insulation under our slabs and along the slab perimiter. This insulation is R3.9/inch - we typically use R10 in our 2x8 walls and R20 for our 2x10 wall assembly.
We use dry-blown cellulose in our ceiling cavities. R50 is our standard for our 2x8 wall assembly, R60 in our 2x10 wall assembly.