How Unvented Roof Assemblies Help Your Home

 Depending on the date of construction, the roof of your home may deal with heat and moisture issues differently. Older homes often feature conventional ventilated attics, where outside air is allowed to circulate freely. However, many North American homes that have been built in recent decades (an estimated 100,000 homes have been constructed since 1995) feature an unvented roof design. This change in design has resulted in great benefits- but also new challenges- to home energy performance.

Air Circulation and Your Attic

While you may not spend a lot of time in your attic, it is important to remember that it is connected to the rest of your house. Air conditioning equipment, ductwork, access hatches and recessed lighting can all act as passages between the attic and living spaces of your home. Changes in air pressure from weather or even mechanical equipment can cause air to flow freely between these passages, and this can mean energy waste for homes with improperly sealed and insulated attics. For hot, humid climates, outside air can condense on equipment located in attic spaces, which can also translate into premature building material degradation and air quality issues. Where ventilated attics maintain thermal, moisture and air issues boundaries inside your home, unvented roof assemblies act instead to relocate these boundaries to the outside of your home and onto the roof deck.

A Safe, Energy-Efficient Option

Reports have shown that even when air sealing is done well, temperature differentials can still exist between the attic and ductwork of up to 150°F. With a ventilated attic, you are essentially opening your home to the outside elements. For those in colder climates, snow can blow in through vent openings, leading to moisture damage or mould growth in the roof assembly. Rain can do the same, while those in areas prone to wildfires may be at increased risk of roof fires caused by the entry of burning embers through roof vents.

Increased Living Space

By moving air, moisture and thermal boundaries to the outside of your home, you are in effect increasing the size of your home. With controlled humidity and temperature levels, many homeowners are using their finished attics as additional living or storage space.

Making the Most of your Unvented Roof

To minimize heat loss and damage (not to mention maximize utility bill savings!) homeowners should ensure that their roof assemblies are properly sealed and insulated. This includes both the roof itself, as well as the connections between the attic and rest of your home. A home energy consultant can help you identify ways in which your home energy performance can be increased.