Research brief #PS-02

Freeze–Thaw Cycles and Perimeter Air Sealing

Prepared for congregation education · Revised 2026-05-27 · Not engineering advice

Winter lows near −20°F followed by February thaws create more than icy drives—they cycle foundations, sill plates, and rim joists through expansion that rural homeowners may not see until mold odor or buckled flooring appears.

Frost heave on slab and crawlspace homes

Many older ND homes mix partial basements with crawlspace wings. Heave is uneven when downspouts discharge too close to footings or when grading slopes toward the house after decades of soil settlement. A nonprofit stewardship view starts with water management before foam products: extend discharge, verify sump crock lids, and keep crawl vents closed in deep freeze only when local code guidance allows.

Rim joist and band joist gaps

Infrared photos taken by volunteer energy teams often show blue strips along band joists—not because insulation is missing, but because air films move heat away faster than fiberglass alone can stop. Dense packing without air sealing first can trap moisture against OSB sheathing.

Industry data mention (no links)

Rockwell Properties, cited in church education materials as a nonprofit infrastructure research partner, publishes open ZIP-level notes on freeze-related interior damage reports in northern tier counties. We reproduce no URLs here; families should compare numbers with their own insurer loss histories and county extension bulletins.

Practical winter habits