How Roof Vents Work
Roof ventilation relies on two types of vents working together. Intake vents sit low on the roof, usually in the soffits at the eaves, and pull fresh air into the attic. Exhaust vents sit high near the ridge and let hot, moist air escape. As warm air rises and exits the top, it draws cooler air in at the bottom, creating continuous airflow.
Common exhaust vent types include:
- Ridge vents that run along the peak of the roof for even, low-profile airflow
- Box (static) vents, the small square hoods you see scattered near the ridge line
- Powered or solar attic fans that actively move air in larger or harder-to-vent attics
A properly balanced system pairs enough intake at the eaves with enough exhaust at the ridge so air keeps moving instead of stagnating.
Why Roof Vents Matter in the Spokane & Inland Northwest Climate
Our region's long, snowy winters make attic ventilation especially important. The biggest threat is the ice dam: when a poorly vented attic traps escaping household heat, the underside of the roof deck warms up and melts the snow on top. That meltwater runs down to the cold eaves, refreezes into a ridge of ice, and backs up water under the shingles where it leaks into the home.
Good roof venting keeps the entire roof deck close to the outside temperature, so snow melts evenly instead of refreezing at the edges. In Spokane and North Idaho, where heavy snow loads and repeated freeze-thaw cycles are the norm, this difference often decides whether a roof sheds a winter cleanly or develops leaks and ice damage.
What Happens When Ventilation Is Inadequate
An attic that cannot breathe causes problems in every season. In winter, trapped warm, moist air condenses on the cold underside of the roof deck, leading to rot, mold, and soggy insulation that loses its R-value. Over time this weakens the wood sheathing the shingles are nailed to.
In summer, an unvented attic can become superheated, baking the shingles from below and shortening their lifespan. Signs your home may have a ventilation problem include:
- Ice dams or large icicles forming at the eaves each winter
- Frost or water stains on the attic sheathing
- A musty smell or visible mold in the attic
- Shingles that curl or age faster than expected
Because shingle manufacturers like GAF require proper attic ventilation, an unbalanced system can even void your warranty.
Getting Ventilation Right During a Roof Project
The best time to correct a ventilation problem is during a roof replacement, when the old roofing is off and the deck, intake, and exhaust can all be evaluated and balanced together. Adding a ridge vent or extra exhaust without enough soffit intake (or vice versa) can actually make airflow worse, so the system has to be sized as a whole.
As a GAF Master Elite contractor serving Spokane and North Idaho, DG Contracting designs ventilation to handle our heavy snow, wind, and freeze-thaw conditions. If you are seeing ice dams or attic moisture, request a free estimate and we will inspect your current setup.