How do soffit vents work in the attic, and how can I check them?
Short answer. From inside the attic, working soffit vents show up as daylight and moving air along the eaves, with baffles holding insulation back so the air can travel up under the roof deck. If insulation is packed tight against the deck at the eaves, or there is no light at all even though the soffit outside looks vented, the intake is blocked.
What to look for in the attic
- Go up on a sunny day with a flashlight, staying on the joists.
- Switch off the flashlight near the eaves and look for light coming in at each rafter bay.
- Check for baffles: foam, plastic or cardboard chutes stapled to the underside of the deck between rafters.
- Look for insulation pressed against the deck at the eaves.
- On a breezy day, feel for air movement near the eaves.
The hidden problem: vented panels over solid wood
Many Georgia homes had vinyl or aluminum soffit installed over the original plywood soffit. The new panels are perforated, but unless someone cut openings in the plywood behind them, no air gets through. From the attic you will see solid wood and no light, even though the house looks vented from the yard.
Fixes
- Install baffles in each bay with intake and pull insulation back.
- Cut openings in old wood soffit behind perforated panels, or remove the wood.
- Add soffit vents where the soffit is solid.
- Do not block bays to stop drafts; the attic is supposed to be ventilated.
Safety
The eaves are the hardest part of the attic to reach. Watch for nails, wiring and wasps, and never step between joists. Georgia attics get dangerously hot by late morning in summer, so go early. Read roof ventilation basics and attic heat and shingles.