Component
What Is a Soffit?
Also called: eave soffit, soffit panel
A soffit is the finished surface on the underside of a roof overhang, spanning from the wall to the fascia. Vented soffits are the intake of the attic ventilation system: they draw outside air in at the eaves, which exits at the ridge, keeping the attic cold in winter and cooler in summer.
In plain English
Stand under the edge of your roof and look straight up: the flat panel you see is the soffit. If it has small holes or slots, your attic is breathing through it — air enters there, washes along the underside of the roof deck, and leaves at the ridge vent.
How soffits works
Soffits close the eave cavity against weather and pests and carry the intake half of passive attic ventilation. Balance matters: ridge exhaust without sufficient soffit intake pulls air from the house instead (along with heated, moist indoor air), while blocked soffits — usually from attic insulation pushed into the eaves — disable the system entirely. Baffles hold an air channel open above the insulation. Material matters less than airflow: aluminum and vinyl soffit panels dominate for rot-proof low maintenance, with perforated or lanced profiles supplying intake area.
Why it matters for your roof
Almost every "roof problem" in winter — ice dams, attic frost, condensation drips, mold on sheathing — starts with the soffit-to-ridge airflow loop. The soffit is half that loop. It's also the detail most often defeated by well-meaning insulation work.
Common problems
Insulation blocking the intake; painted-over or undersized perforations; pest entry through damaged panels; moisture staining that signals attic condensation or gutter overflow.
Don't confuse it with
Not to be confused with fascia — the vertical trim at the roof edge; the soffit is the horizontal underside.
- Soffit vs fascia (the vertical board the gutter hangs on)
- Vented vs solid soffit
Regional & climate notes
Most relevant in: Snow-heavy climates, Humid climates.
Frequently Asked Questions
How do I know if my soffits are vented?
Look up at the overhang: perforations, slots, or screened strips mean vented. Then check in the attic that daylight or airflow is actually present at the eaves — insulation often blocks it.
How much soffit ventilation do I need?
Codes typically require 1 sq ft of net free vent area per 150 sq ft of attic (1:300 with a balanced ridge/soffit split). Intake should equal or exceed exhaust.
Do soffits matter under a metal roof?
Yes — the ventilation loop protects the attic and deck under any covering, and a cold, dry attic is part of ice-dam prevention even on a metal roof.
Related terms
See how an Interlock® lifetime aluminum roof handles this — engineered, manufactured, and installed by one company.
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