How Much Attic Ventilation

In other words the entire vent opening doesn t count as vented space.

How much attic ventilation. However if your attic has blocked soffit vents and is not well sealed from the rest of the house attic fans will suck cool conditioned air up out of the house and into the attic. Soffit vents help increase the airflow are easy to install and only cost about 3 per 8 ft. To keep air flowing your roof needs just the right amount of attic ventilation. According to the national roofing contractors association nrca a power vent with an airflow rate of 1 0 cubic foot per minute per square foot of attic space measured at the attic floor is generally considered to be equivalent to a 1 150 ventilation ratio.

The following product options will allow you to achieve an intake nfva of 528 square inches. Federal housing authority recommends a minimum of at least 1 square foot of attic ventilation evenly split between intake and exhaust for every 300 square feet of attic floor space. How much attic ventilation is enough. You can also contact your local municipality to check on building code in your area.

We show you how to install soffit vents step by step to improve your attic ventilation. Ventsure inflow intake vent. Most building codes require a ratio of 1 150 ventilation space to attic floor space. In no case should the amount of exhaust ventilation exceed the amount of intake ventilation.

What does the code require. That said air resistance and interference such as vent grates reduces the area of true ventilation. Ideally the total vent space should be equally divided between lower soffit vents and upper vents at the roof peak. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq.

The basic formula for a typical residence is 1 foot of passive vent opening per every 150 square feet of attic size. Generally speaking you need a ratio of 1 300 where for every 300 square feet of ceiling space you need 1 square foot of attic ventilation. Allows cool dry air to enter the attic. Attic ventilation keeps the air moving and stops mold from growing but too much ventilation can be just as bad as having none.

Here s how to install soffit vents step by step to improve the airflow in your attic. Always have a balanced ventilation system. Choose one of the following products to meet the recommended intake nfva of 528 square inches.