Should I use spray foam or batt insulation in my Vancouver crawl space?

For Vancouver crawl spaces, batt insulation is typically the better choice due to our wet climate and the need for moisture management. Spray foam can trap moisture in wood framing, leading to rot and mold issues that are particularly problematic in our rainy Lower Mainland environment.

Batt insulation (fiberglass or mineral wool) allows the crawl space to "breathe" and lets any moisture that does penetrate dry out naturally. This is crucial in Vancouver where we receive over 1200mm of annual rainfall. Install R-20 to R-24 batts between floor joists with the vapor barrier facing up toward the heated space. Ensure proper ventilation with foundation vents that remain open year-round — despite what you might read online about closing them in winter, BC's mild climate and high humidity make continuous ventilation essential.

Spray foam creates an airtight seal that can be problematic if any moisture gets into the wall or floor assembly. While it provides excellent insulation value and air sealing, it can trap water vapor against wood framing members, potentially causing structural damage over time. If you do choose spray foam, it must be applied by certified professionals and requires careful moisture management strategies.

Vancouver-specific considerations include our freeze-thaw cycles and the fact that many homes built before 1980 lack proper vapor barriers. The BC Building Code 2024 requires R-20 minimum for crawl space insulation, but R-24 is recommended for better energy performance under the BC Energy Step Code. Most Vancouver crawl spaces also need attention to drainage, foundation waterproofing, and proper grading to direct water away from the foundation.

Professional guidance is recommended for crawl space insulation, especially if you're dealing with moisture issues, inadequate ventilation, or structural concerns. A building envelope specialist can assess your specific situation and recommend the best approach. Never attempt to seal or insulate a crawl space that has active moisture problems — address drainage and waterproofing first.

Next steps: Have a qualified insulation contractor assess your crawl space for moisture issues, ventilation adequacy, and current insulation condition. Budget $3-6 per square foot for professional batt installation, or $8-12 per square foot for spray foam if that's determined to be appropriate for your specific situation.