How Much Attic Ventilation Is Enough

Of vent for every 300 sq.

How much attic ventilation is enough.

So if your attic is 1 500 sq. Do not use gable vents because it s possible to draw rain and snow into the attic. Throughout the roofing industry there is a widespread lack of agreement over adequate attic ventilation. But what type works best and how do you know when enough is enough.

Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca. Ideally the total vent space should be equally divided between lower soffit vents and upper vents at the roof peak. Before we explore how to ventilate an attic space it is prudent to understand how much ventilation is needed. Much of the debate stems from the tremendous variation in climate across north america.

That said air resistance and interference such as vent grates reduces the area of true ventilation. Ventilation can be accomplished using various products and techniques. This characteristic of air may be used to help create a flow of air ventilating the attic. How much attic ventilation is enough.

Of vent space for every 150 sq. In all seasons the attic space is warmer than the outside air. The uniform building code requires that the amount of venting area in the attic be equal to 1 150 of the area of the floor and in most circumstances it allows a ratio of 1 300 if the venting area. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq.

Allows cool dry air to enter the attic. This results in a constant upward air movement due to the buoyancy of warmer air. 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. To keep air flowing your roof needs just the right amount of attic ventilation.

Ft you divide that by 150 to get 10 sq. The rule of thumb on the amount of vent space needed is approximately 1 sq. We hear this question quite often from zimmerman exteriors customers. Most building codes require a ratio of 1 150 ventilation space to attic floor space.

Ventsure inflow intake vent. The following product options will allow you to achieve an intake nfva of 528 square inches. In other words the entire vent opening doesn t count as vented space. Choose one of the following products to meet the recommended intake nfva of 528 square inches.