Quick definition
The finished underside of the roof overhang, between the fascia and the exterior wall. It often contains intake vents for attic ventilation.
Look up under the edge of the roof and you're looking at the soffit. Besides closing off the overhang, vented soffit is usually where an attic breathes in.
What problems happen with soffit?
- Blocked vents: attic insulation pushed against the soffit, or vents painted over, stops airflow. Baffles keep the path open.
- Water damage: stains, sagging or rot from a leaking roof edge or overflowing gutters.
- Pest entry: loose or damaged panels let animals in.
- Too little vent area: solid or under-vented soffit starves the attic of intake air.
What is soffit?
Soffit is the panel or boarding that covers the underside of the roof overhang, running from the fascia back to the exterior wall. It comes in vinyl, aluminum, wood and fiber cement, either solid or perforated with vents.
What does soffit do?
- Closes the overhang so weather, birds and insects can't get into the rafters.
- Provides intake air for attic ventilation when it is vented.
- Gives the underside of the roof a finished look.
Vented vs solid soffit
| Type | What it does | Where it's used |
|---|---|---|
| Vented (perforated) | Lets outside air into the attic | Over attic spaces that need intake ventilation |
| Solid | Closes the overhang with no airflow | Porches, gable overhangs and areas with no attic behind them |
How does soffit work with attic ventilation?
Most attics are ventilated from low to high. Air enters through the soffit vents at the eaves and leaves through exhaust vents near the top of the roof, such as a ridge vent. That flow carries heat and moisture out of the attic. Without enough intake at the soffit, exhaust vents can't work properly.
Soffit vs fascia
Soffit is the horizontal underside of the overhang. Fascia is the vertical board along the roof edge. They meet at the corner of the eave.
What it means for you
What Soffit means for homeowners
Check that soffit vents aren't painted over or clogged, and that panels aren't loose or stained. A very hot attic or condensation in winter can mean the soffit isn't letting enough air in.
Frequently asked questions
Sources
- International Residential Code, Section R806: Roof Ventilation. International Code Council.
Tier 1 authority 路 code - Residential Asphalt Roofing Manual. ARMA.
Tier 2 authority 路 industry - Soffit and ventilation product manufacturer instructions. Technical Reference.
Tier 1 authority 路 manufacturer