Window Condensation

Three Types of Window Condensation

Interior Surface Condensation

Water droplets on the inside surface of your windows mean indoor humidity is high and the glass is cold enough for moisture to condense. This is a humidity issue, not a window defect.

Solutions: Reduce indoor humidity with ventilation, exhaust fans in bathrooms and kitchens, or a dehumidifier. Make sure your home has adequate air exchange.

Exterior Surface Condensation

Condensation on the outside of windows typically happens on cool mornings when humid outdoor air meets glass that's colder than the dew point. This actually indicates your windows are working well—they're insulating effectively.

Solution: None needed. This is normal and will evaporate as the day warms.

Condensation Between Panes

Moisture visible between the glass panes (inside the sealed unit) means the seal has failed. This won't go away and indicates the window's insulating value is compromised.

Solution: Sealed unit replacement. We remove the failed glass unit and install a new one.

When to Be Concerned

• Condensation between panes (seal failure—needs repair)
• Interior condensation causing water damage to sills or walls
• Persistent interior condensation with mold growth
• Condensation in a home with already-low humidity

Humidity Control Tips

Ottawa Valley winters make humidity management challenging. Cold air holds less moisture, so when you heat cold outdoor air, relative humidity drops. But activities like cooking, showering, and even breathing add moisture back.

Target indoor relative humidity of 30-40% in winter. Higher levels cause condensation on cold windows; lower levels feel uncomfortable and can cause static electricity and dry skin.