Windows, Doors and Skylights

Humidity In Your Home

A certain amount of humidity in your home is desireable for comfort during the colder months. Windows, doors and skylights that are not energy efficient will often have condensation or frost on them even when the indoor humidity is at a reasonable level. This condensation, in addition to obscuring the view, can lead to mould formation on the frames and sashes. An ENERGY STAR qualified product will allow a higher indoor humidity before condensation occurs. You may even be able to turn down your thermostat and still feel comfortable. Because humidity levels are normally higher in bathrooms and kitchens, consider installing a product qualified for Zone D in these rooms to reduce or eliminate condensation on the windows.

It is also important for you to know that high indoor humidity is not recommended because it can lead to the formation of mould in areas of the house other than the windows, doors or skylights. During the heating season, it is recommended that the average indoor humidity be less than 40 percent when outdoor temperature is less than -10°C.

If the indoor humidity is too high in your home, try the following:

• Turn off the humidifier on your furnace;
• Ensure that the clothes dryer is vented to the outside;
• Use bathroom and kitchen fans that vent to the outside when bathing or cooking;
• Store firewood outside;
• If you have a mechanical ventilation system, make sure that it is working properly and that it is turned on.

Some airtight houses were built without mechanical ventilation systems. If high humidity is a chronic problem, consider having a heat recovery ventilator system (HRV) installed.

More information on mould from the Canadian Mortgage and Housing Corporation