Attic ventilation is one of the least glamorous topics in roofing and one of the most important. Improper ventilation is responsible for a meaningful percentage of the premature roof failures we see throughout The Treasure Valley. In many cases the shingles themselves are fine. The roof underneath them failed because of what was happening in the attic.
How Attic Ventilation Works
A properly ventilated attic uses the stack effect to move air continuously: cool outside air enters through soffit vents at the eaves, travels up through the attic space, and exits through ridge vents near the peak. This continuous airflow keeps the attic close to outside air temperature in both summer and winter.
Common Ventilation Problems We Find in Boise Homes
- Blocked soffit vents: Insulation installed incorrectly covers the soffit vents, stopping cold air intake at the eaves.
- Inadequate vent area: Older Boise homes were often built with minimal attic ventilation by today's standards.
- Mixed vent types at the same level: Mixing ridge vents and gable end vents can short-circuit airflow.
What Proper Ventilation Adds to Roof Life
Studies by shingle manufacturers consistently show that properly ventilated roofs last 15 to 25% longer than identical roofs on poorly ventilated attics. Manufacturer warranties from Owens Corning and CertainTeed both require proper ventilation as a condition of their extended warranties.