Crawl Space Insulation Code Guide
Crawl Space Insulation Code Guide
Alberta NBC 2023: Section 9.18 at a Glance
Alberta declared the National Building Code – 2023 Alberta Edition in force on May 1 2024, which means every new foundation or renovation permit must now meet its crawl-space rules. Under Article 9.18.1.3 a crawl space is judged heated when it carries un-insulated ducts or is not separated from conditioned rooms; in every other case it is unheated. The distinction matters because only heated crawl spaces inherit wall and rim-joist RSI targets from the living area above, whereas unheated spaces follow more modest minimums.
For one- and two-family homes in Climate Zone 7A (Peace River, High Level, Hay River) the prescriptive path still asks for RSI 1.96 (≈ R-11) on interior crawl-space walls plus a continuous Class I vapour retarder over exposed soil. Builders who bump their projects to Tier 3 energy performance often choose to thicken insulation to RSI 2.64 for extra blower-door margin, but Tier 1 remains acceptable when the assembly stays under 50 Pa air-leakage limits. In the Northwest Territories (Zone 8A) building officials reference the same NBC tables yet encourage RSI 2.64 outright because design temperatures sink below -40 °C.
Because medium-density closed-cell spray foam achieves roughly RSI 0.007 per mm, two 50 mm passes satisfy both the thermal and vapour barriers in a single operation. Once the foam bonds to concrete or preserved wood, it also acts as the required air barrier, eliminating poly sheeting and the maze of tape joints that accompany it. That airtight layer blocks soil-gas entry, which is critical along the Peace River Radon Belt where test kits often exceed Health Canada’s 200 Bq/m³ guideline.
Beyond Insulation: Vapour, Radon and Air Control
NBC Sentence 9.18.3.2 asks for a 0.15 mm ground sheet lapped 150 mm at seams and sealed to walls. We first spray a low-lift skim to bond the polyethylene, then return with the full-depth lift so sheet edges become locked in place. That method means the vapour barrier never peels or tears when plumbers crawl in later, and the foam’s rigidity bridges small cracks where mice or carpenter ants might otherwise slip through.
Where municipal inspectors reference CAN/CSA-B662 Radon Rough-In standards we extend the foam jacket over the drain tile to ensure suction points remain airtight for future mitigation fans. The R-value vs cost comparison by Green Building Canada explains why spray foam’s higher price per square metre can still win on lifecycle cost once air-sealing and radon protection are tallied.
Our Fusion Foam Approach in Northern Climates
We start every project with a moisture probe of concrete and sill plates, because CAN/ULC-S705.2 voids its warranty if substrate moisture tops 19 %. Heated trailers keep drums within the 16 °C to 30 °C window even during a Hay River cold snap, and digital logs record pressure, temperature and lift thickness so inspectors can sign off without extra site visits.
Once the ground sheet is locked, we spray the wall in two 50 mm lifts, waiting for exotherm to fall below 48 °C before the second pass. Each corner receives an angled fillet of foam to eliminate the vertical air-channel effect documented in NBC Appendix A. Because the foam now serves as vapour control, we omit separate poly at the underside of the floor joists and instead install unfaced drywall as the 15-minute thermal barrier required by Part 3 and Part 9.
Homes that route supply ducts through the crawl space become heated by definition, so we increase thickness to match the above-grade wall RSI and seal duct joints with mastic to avoid energy penalty points under NBC Table 9.36.8.8. Where plans call for hydronic loops or HRV cores in the space, we insulate plumbing and pipe hangers before the final blower-door test to ensure the entire plenum performs as one envelope.
Fusion Foam’s crews travel with self-contained power and heat so remote projects never sit idle waiting for utility hookups. That mobility lets us service cabins on Great Slave Lake and farm shops across Peace Country with the same code-compliant result.
Throughout the process we reference our insulation-renewal program for owners who must first strip mouldy fibre batts. We remove debris, disinfect wood and deliver a conditioned crawl space that stands up to wind-driven snow and summer humidity alike.
Call Fusion Foam for Ag, Commercial & Residential Crawl Space Insulation
If you are planning a build or retrofit in Alberta or the Northwest Territories and need crawl space insulation that passes inspection the first time, reach our team through the Fusion Foam contact page. We will size the foam, document CAN/ULC-S705.2 compliance and leave you with an airtight, radon-safe crawl space ready for decades of northern winters.