When is a problem with condensation & fogging urgent?
Treat a condensation & fogging problem as urgent when it creates an immediate safety exposure, active damage, loss of an essential service in dangerous weather, or rapid worsening.
What this means
Condensation & fogging covers interior moisture, between-pane fogging, frost, and humidity. Relevant observations include Condensation forms inside, Fog is trapped between panes, Ice forms on the inside, Only one room has wet windows, Window trim shows mould-like spots. The correct response depends on age, design, climate, usage, installation, recent work, and the exact manufacturer instructions; these observations narrow next steps but do not prove a failed part.
Safe checks
- Identify active water, heat, smoke, odour, arcing, movement, sewage, structural change, or loss of essential service.
- Move people away and use only a normal safe shutoff or disconnect when accessible.
- Call emergency services for immediate danger; otherwise contact the relevant qualified trade.
Stop and get help if
- Leave or isolate the area for fire, gas, carbon monoxide, electrical exposure, collapse, sewage, or rapidly spreading water.
- Get qualified assessment when a hidden, growing, recurring, or structural condition is suspected.
Which professional to call
Use a qualified building-envelope specialist when the condition exceeds safe user access or the visible checks do not explain it.
Find the relevant tradeSource and method
This answer combines HomeSOS's structured triage with safety boundaries supported by a public source. It does not replace inspection.
Health Canada: Home safetyReviewed August 12, 2026