Have you ever wondered what is actually happening when you spot moisture on or around your windows?  Condensation on windows occurs when warm, moist indoor air meets a cold glass surface and cools down, causing the water vapour in the air to turn into liquid droplets.  But what are the main causes?  BC Building Science breaks it down and offers some tips and tricks to help solve your moisture issues.

 

Condensation On the Inside of Windows

Cause: High indoor humidity (cooking, showering, clothes in the dryer, etc.).

Fixes:

• Run a dehumidifier or improve ventilation (open a window, use bathroom / kitchen fans).
• Keep blinds / curtains open to allow airflow near the glass.
• Reduce indoor moisture (cover pots when cooking, shorten showers, vent dryers outside).
• Plants and aquariums add humidity so consider temporarily moving them if needed.

 

Condensation On the Outside of Windows

Cause: Warm, humid outdoor air hitting cool glass.

Fixes:

• This is normal and a sign your windows are well-insulated. Nothing to fix!

 

Condensation Between the Panes (inside double / triple-pane glass)

Cause: Failed window seal allowing moisture inside.

Fixes:

• This usually means the insulating glass unit (IGU) has lost its seal and may need to be replaced.

 

Daily Habits to Prevent Condensation

• Air out your home every day. Open windows for 5–10 minutes (even in the winter) to let moist air escape.
• Use exhaust fans. Turn on fans while cooking or showering and leave them running ten minutes afterwards.
• Wipe down condensation on windows in the morning. A quick towel or squeegee prevents mold from forming on sills and frames.
• Keep blinds / curtains slightly open. Air circulates against the glass instead of trapping moisture.
• Reduce sources of humidity. Cover pots while cooking, vent clothes dryers outside, hang fewer clothes indoors, move plants / aquariums away from the windows.
• Use a dehumidifier. Aim for 30–50% indoor humidity.  Rule of thumb:  too low = dry skin, too high = condensation.

 

Outsmarting pesky condensation is indeed possible!