How to Vent Flat Roofs
- 1). Install 1 square foot of flat roof vent for every 300 square feet of attic space. If your attic is 1,500 square feet, then install 5 square feet of ventilation. Dedicate half for air intake in the soffits and the other half for exhaust on the roof.
- 2). Build a vent stack into the flat roof during construction. Vent stacks come in many different shapes and sizes, depending on the size of the roof. Some are quite large and luxurious; others are nothing more than just a pipe. Because proper flat roof ventilation is essential to a quality roof, the more ventilation, the better.
- 3). Stack vents are generally 2-inch-diameter pipe. The spacing recommendation is about one every 1,000 square feet. Custom-made vents are usually larger in diameter--6 inches or more. Insulated box vents may be even larger and spaced further apart. If the full benefit of a venting system is to be achieved, stack venting should be combined with perimeter venting, and intentional venting passages through the insulation should be provided.
- 4). Create cross ventilation on your flat roof by using roof-mounted intake and exhaust vents. The Aura Ventilator and the Pop Vent are high performance flat roof ventilating systems. They work continuously and are non-electric. They conserve energy and extend roof life. They are wind tested at 110 mph, and have lifetime guarantees (see Resources below).
- 5). Install breather vents to your flat roof to remove moisture from wet insulation. These vents consist of vertical pipes or stacks that are open to the outside air and shielded from the rain by a cover. They penetrate the roofing membrane to provide a path for moisture to reach the outside. Usually a number of such vents are aligned in one or more rows.
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