Roof ventilation isn’t about adding “a vent.” It’s about creating a balanced airflow path that removes heat and moisture from your attic.
In real-world Bay Area homes, poor ventilation can show up as moldy attic sheathing, musty odors, premature shingle wear, and uncomfortable indoor temperatures.
Ventilation basics: intake vs exhaust
- Intake (low): usually soffit vents or low roof vents that bring fresh air into the attic.
- Exhaust (high): ridge vents, box vents, or powered vents that let warm/moist air escape.
The goal is a continuous flow from low to high. Too much exhaust with not enough intake can actually pull air from the home (through ceiling gaps), bringing moisture with it.
Common ventilation systems
Ridge vent + soffit vents (most common)
When installed correctly with clear intake, ridge vents provide even exhaust across the roof peak.
Box vents / turtle vents
These work best when distributed properly and paired with adequate intake. Too few vents can leave “dead” zones where air stagnates.
Gable vents
Older homes often have gable vents. They can help, but they don’t always move air evenly through the attic unless paired with the right intake/exhaust strategy.
Powered attic fans
Powered fans can help in specific cases, but they’re not automatically “better.” If intake is weak, they may pull conditioned air from the house and increase energy use.
Signs your attic ventilation is underperforming
- Musty odors or visible mold on rafters/sheathing
- Rust on nails, straps, or metal fasteners
- Excess attic heat that lingers into the evening
- Frequent condensation on skylight frames in winter
- Shingles that look “cooked” or prematurely brittle
Quick homeowner check (safe + simple)
- Look at your soffits: are vents painted over or blocked?
- In the attic, confirm insulation isn’t covering intake vents.
- Check bathroom fan ducts: they should terminate outside, not into the attic.
- Look for baffles at eaves so air can flow above insulation.
Ventilation upgrades that usually pay off
- Clearing or adding soffit intake
- Adding baffles to keep airflow open at the eaves
- Installing a continuous ridge vent (when roof design allows)
- Sealing ceiling air leaks (can lights, attic hatch, top plates)
Next step
If you suspect ventilation issues, it’s smart to evaluate it during any repair or replacement plan. Ventilation is part of a durable roof system—along with flashing and water management. If you’re seeing moisture or mold, start with an inspection via roof repair or request an estimate.