Attic Insulation Code Alberta
Unvented Roof Clause and Variance 19-BCV-022
The National Building Code – Alberta Edition says that every attic or cathedral ceiling must be ventilated unless “it can be shown to be unnecessary.” Article 9.19.1.1 creates that opening, but an authority still needs formal proof. Alberta issued province-wide Variance 19-BCV-022 to spell out when an unvented roof insulated with spray polyurethane foam is acceptable.
The variance cites Sentence 9.19.1.1 and allows a sealed roof deck when closed-cell foam provides the full thermal resistance and doubles as the vapour and air control layer. In practice that means we spray medium-density foam directly against the roof sheathing, then finish with gypsum or an intumescent coating so the assembly earns the 15-minute thermal-barrier rating required by Part 3 and Part 9.
Peace Country, High Level and Hay River lie in Climate Zone 7A, where Tier 1 of Section 9.36 calls for RSI 6.0 (about R-34) at the roof deck. Our closed-cell product delivers roughly RSI 0.007 per millimetre, so 175 mm of foam passes Tier 1 without ventilation. Builders who step up to Tier 3 add only another 20 mm. In the Northwest Territories, Zone 8A nudges the minimum higher, so we thicken the foam to 200 mm and still keep the roof cavity slim because no vent channel is needed. That slimmer section gives designers freedom to push ceiling heights without exceeding overall building height caps.
CAN/ULC S705.2 Daily-Log Discipline
Spray foam is accepted under Variance 19-BCV-022 only when the installation meets CAN/ULC S705.2, the national site-practice standard for medium-density foam. S705.2 demands that every project generate a Daily Work Record noting substrate temperature, ambient humidity, pressure calibration and lift thickness. The standard also obliges the installer to carry a photo licence that proves current training status (Standards Council of Canada). We run those logs on a cloud app so municipal inspectors can view them in real time, which speeds approvals in remote districts where a second trip could mean a 600-kilometre drive.
Thermal-Barrier Choices in Crawl Spaces and Kneewalls
Because the foam in an unvented roof now acts as insulation, vapour retarder and air barrier, the only remaining code item is fire protection. The default is 12.7 mm Type X gypsum, yet Alberta accepts intumescent coatings with CAN/ULC-S124 listings when space is tight. Our crews document wet-film thickness and cure time to show equivalency before the inspector arrives. The same approach serves crawl-space walls, where Sentence 9.18.2.1 calls for RSI 1.96 insulation and a ground vapour retarder. Two passes of foam meet both clauses in one operation and seal radon entry points, a bonus in Hay River where soil readings can spike.
Energy-Audit Payback
Unvented foam roofs reduce air leakage because there is no vent chute interrupting the air barrier. Tier 3 homes in Zone 7A must test below 2.5 ACH @ 50 Pa; our completed attics usually fall under 1.0 ACH. That airtightness lets mechanical designers downsize heat-recovery ventilators and furnaces, trimming both capital cost and emissions. For owners curious about basic chemistry we recommend the public overview of spray foam on spray foam insulation which explains why the material doubles as an air seal as soon as it hardens.
Every attic project begins with a site review and ends with an electronic code-compliance file that you can forward to appraisers, insurers and warranty providers. If you have existing batts that sag or show frost stains, consider our insulation-renewal service. We remove damaged fibres, spray closed-cell foam to the exact thickness required by Variance 19-BCV-022 and leave your home ready for drywall the same day.
We travel throughout northern Alberta and the Northwest Territories. Visit our contact page to schedule a code-ready attic upgrade that will keep winter heat where it belongs.