Winterizing Your Home: Seal That Leaky Ductwork
In addition to an uncomfortably drafty home and high heating bills, unregulated air movement can actually lead to moisture damage.
There is a fair amount of humidity produced by bathing, cooking and laundering, as well as by our mammalian metabolism (breathing, perspiring). This moisture is pushed and drawn through the layers of your home along with air; particularly buoyant, warm air; leading directly to various sorts of damage, such as ice dams on the roof, frost along windowsills, sweaty, rotting window sashes, mildew and rot inside wall cavities and stained or soggy Sheetrock.
Mechanical ventilation in the form of range-hood fans, bathroom exhaust fans and dryer vents helps to alleviate or prevent these problems by exhausting moisture to the outdoors. It also helps to make the living space safer by removing volatile organic compounds (VOCs) and byproducts of combustion from stoves, furnaces and water heaters.
Ideally, a mechanical means of ventilation works in combination with tighter construction to provide your home with a safer atmosphere over which you can exercise greater control of airflow. If your home uses a forced-air heating system (nearly two-thirds of the homes in North America do) the vents, fans and ductwork constitute the ventilation system and can often be modified or added to for exhaust purposes. Properly installed, sealed and maintained, this network removes toxins and excess moisture that leads to damage.
Take these steps toward troubleshooting leaky ductwork, and making it more efficient:
- Seal ductwork joints with a fiber-reinforced mastic (a pasty goop) rather than duct tape; it holds up better on warm metal.
- Wrap ductwork with insulation, especially on long runs. It will help deliver heat where you want it, instead of radiating it into the walls or basement. You can find several choices for this job at any home-improvement center; rigid, foil-backed fiberglass duct board (best for square ducts) is one type.
Be sure that the hoses used for exhaust fans and clothes dryers are in good condition, and that the vent seams are sealed indoors (where they enter the ceiling) and out (where they exit the wall or roof).
If you are not completely sure what's causing heat loss or draftiness in your home, it might be to your advantage to have tests performed by insulation contractors or your local utility company. Sometimes the utility companies will do this for free. They could take infrared photographs to detect areas of high heat loss, or possibly perform a blower-door test. Blower doors measure the amount of air change in your home, and that tells a lot about the tightness of a home's construction.
These tests will help isolate sources of heat loss that might otherwise be difficult to detect, particularly in new homes that are already above average in weather tightness. The results of an infrared photo or blower-door test will provide you with a bigger weatherization picture, allowing you to make faster, more effective improvements toward a more comfortable living environment.