Wall Assembly Double Check – Zone 6 BC, Canada

This one is a homeowner-to-homeowner forum post, not a policy or program update, but it offers a useful reality check for anyone building or deeply renovating a house. A homeowner in Slocan, British Columbia, building his own home, posted his full wall and roof design for feedback before closing up the walls. His plan includes 2x6 framing with rockwool batt insulation inside, taped plywood sheathing for air sealing, a smart vapor membrane, and 1.5 to 2 inches of exterior mineral wool insulation (called comfortboard) outside the sheathing, all vapor-permeable materials meant to let moisture pass through safely rather than trap it. He's aiming for a very tight house, around 1 to 1.5 air changes per hour under blower-door testing, well beyond typical code minimums.

A building science expert who answered his questions confirmed a few points worth knowing if you're considering similar upgrades to your own home. Because all the layers in this wall are vapor-permeable, there's no need to worry about strict insulation ratios that usually apply when foam board is involved. Bumping exterior mineral wool from 1.5 to 2 inches won't noticeably improve comfort. Drywall alone is enough to stop air leaks around interior vapor membranes, so obsessively taping every seam isn't necessary. And vapor barriers work by covering most of an area, so small gaps around framing members make little practical difference.

This is a technical construction detail exchange rather than a rebate or program announcement, so there's no direct action for most homeowners, but it's a helpful look at how professionals think through wall assemblies for durability and comfort.