Ventilation Methods for Metal Roofs

Soffit Vents

• The soffit vents are the lower openings that are placed under the soffit. This is the location under the roof overhang on the sides of the building. The total openings in these vents should be equal to the area of the upper ridge vents for the air flow to be even. Soffit vents are typically slotted metal sheets that allow air flow while keeping animals out of the attic space.

Ridge Vents

• The ridge vents are the top vents on the metal roof. They are installed along the roof peak to encourage the warm air to rise out of the openings. This draws fresh air in through bottom soffit vents completing the cycle. The ridge vents are in the ideal location to create a natural air draw because of warm air's rising properties.

Amount of Vents

• For a typical sloped roof, the amount of ventilation should be a ratio of 1-to-300 to the total floor space of the attic. For a 1,200-square-foot attic, you need four square feet of ventilation. This ventilation needs to be evenly divided between the ridge and soffit vents, or two square feet for each system. If the sloped roof has a pitch below two in 12, the ventilation ratio doubles to 1-to-150.

Turbine Vents

• Mechanical turbine vents use the wind's power to create a fan that draws out the air. You should avoid them for several reasons. These vents require wind to operate, and the attic needs ventilation on calm days as well. They often seize or become very noisy as they age, and they are susceptible to leaking when it rains.