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What is a Soffit Vent?

Soffit vents are openings - covered with a grill - installed on the underside of a roof overhang or other architectural features such as a beam, arch, ceiling, vault, or cornice. They allow air to flow into the attic or the space below the roof sheathing keeping it cool in the summer and allowing damage-causing moisture in the air to evaporate.

Types of Soffit Vents

There are many types of soffit vents on the market including continuous, circular, and perforated vents. Standard soffit vents are 4 to 8 inches wide and rectangular to be installed in the space between rafters. Continuous soffit vents long and narrow to run the length of the eave. Circular vents come in 1 to 8 inch diameters, and perforated vinyl soffits combine the soffit and the vent into one piece of material.

How Do Soffit Vents Work?

Soffit vents permit cold air to enter the attic in order to ventilate it and keep it cold. This reduces the chance of ice damming - when snow melts off a roof from a too-warm attic and then re-freezes at the gutters - which can damage the roof.

During summer months, the natural airflow from the soffit vents allows hot air to move out of the attic protecting roof shingles and removing moisture. According to the US government's ENERGYSTAR, the most common mistake homeowners make is to block the flow of air at the eaves with insulation. ENERGYSTAR advises "never cover attic soffit vents with insulation - use rafter vents and soffit vents to maintain airflow."

Popular Manufacturers of Soffit Vents

  • Alcoa
  • Duraflo
  • Northwest Metal
  • Norwesco
  • Phife