How much soffit ventilation do I need?

Match or exceed your ridge vent exhaust area. IRC requires minimum 1 sq ft net free area per 150 sq ft attic floor (1:300 with balanced system).

Can insulation block soffit vents?

Yes, and it is a common problem. Install rafter baffles (ventilation chutes) at each bay to maintain a clear air path.

Continuous or individual soffit vents?

Continuous vents provide more uniform intake and are preferred for new construction. Individual vents work for retrofits.

Soffit VentGenerating image…

Roofing

Ventilation

$2-$6 per linear foot (continuous) or $5-$15 each (individual)

Soffit Vents: Essential Attic Intake Ventilation (2026)

Prepared by Lumberama's Building Materials Team

|Last updated May 15, 2026|Sources & methodology

Soffit vents are installed in the underside of roof overhangs to allow fresh outside air into the attic, providing the intake half of a balanced ventilation system. They work with ridge or roof vents to create continuous airflow that removes heat and moisture, preventing ice dams and premature roof deterioration.

Key Features

Attic intake ventilation; Continuous and individual styles; Insect-screened; Aluminum or vinyl material; Pairs with ridge vents

Specifications

Continuous vent: 8 in wide strips. Individual vents: 4x16 in or 8x16 in. Net free area: varies by product (6-9 sq in/ft for continuous). Material: aluminum or vinyl.

Applications

Residential soffit areas; Attic ventilation intake; New construction; Retrofit ventilation upgrades; Paired with ridge vents

Installation Overview

For continuous vents, cut a slot in the soffit and install the vent strip. For individual vents, cut rectangular openings and screw vents in place. Ensure insulation baffles are installed at rafter bays to keep insulation from blocking airflow.

Pros & Cons

Pros

✓ Essential for balanced ventilation; Prevents ice dams; Reduces attic moisture; Easy to install; Low cost

Cons

✗ Can be blocked by insulation; Requires cutting soffit material; Insects can nest near vents; Must balance with exhaust; Paint may block perforations

Top Brands

GAF

Air Vent

Lomanco

Construction Metals

Code Requirements

Required per IRC R806 for balanced attic ventilation. Intake ventilation should equal or exceed exhaust ventilation. Net free area per IRC R806.2.

Buying Tips

Buy insulation baffles at the same time - one per rafter bay. Continuous vents give better airflow distribution. Verify net free area meets your ventilation calculation.