Indoor air
Window condensation
Winter glass sweat is common on the coast. How to tell condensation from leaks, and when wet sills matter.
Cold glass and warm indoor air make winter condensation common in BC. Single-pane and weak insulated glass show it first.
Condensation is an indoor humidity and surface-temperature problem. A roof leak usually shows as staining away from the typical sill wet line or during rain regardless of indoor humidity.
Reduce indoor moisture sources: vent bathrooms and dryers outdoors, cover pots, and avoid drying laundry in closed rooms when possible.
Chronic wet sills can grow mold on frames and drywall. Wipe and dry, improve airflow, and fix failed seals. Persistent wall wetness needs a closer look for leaks.
Educational only — not a contractor inspection or bid. When work is structural, electrical, or involves unknown vent chases, hire a qualified local trade.