Q: Why do my new windows have more condensation than my old ones?

A: New windows are more airtight than old ones, which means they trap moisture inside your home. While older windows allowed humidity to escape through leaks, modern windows seal tightly, making existing humidity more noticeable on cold surfaces like glass. The windows aren’t the cause of condensation — they just make it more visible.

Q: What’s the ideal indoor humidity level in winter to prevent condensation?

A: The ideal indoor humidity level during winter depends on the outdoor temperature.

As a general guideline, when it's around –7°C outside, indoor humidity should be kept between 35% and 40%. As the temperature drops, humidity should be lowered accordingly, for example, 30% at –12°C, 25% at –18°C, and as low as 15% when it’s –29°C. Maintaining these levels helps reduce condensation on windows and other cold surfaces.

Q: What causes indoor humidity and condensation in the home?

A: Everyday activities like cooking, showering, doing laundry, and even mopping floors all add moisture to the air. Houseplants, humidifiers, and certain heating systems also contribute. In newer homes or recently renovated ones, moisture from building materials can increase humidity, especially early in the heating season.

Q: How can I reduce condensation on my windows?

A: Try the following steps:

• Use exhaust fans in kitchens, bathrooms, and laundry rooms.

• Open windows briefly each day to let moist air out and fresh air in.

• Check and lower your humidifier settings if needed.

• Ensure attic, basement, and fireplace vents are open.

• Group houseplants together and avoid overwatering.

• Talk to an HVAC professional if condensation persists.