How much ventilation will you need for your space?

September 8, 2016 canplas


Sometimes less is more, which is why we wouldn’t recommend putting 11 roof vents on the roof of a single gable-style home.

So how do you know how to get the perfect number of vents to have your home breathing right?

Here’s our guide on calculating the correct amount of ventilation for your home. We have a calculator on our website which you can find here.

But first, we will explain to you how it works.

We don’t recommend mixing your ventilation.  Choosing a single type of ventilation makes it much easier to ensure that your soffits are breathing air into your home, and your roof vents are breathing this air out.

Here’s our four step process:

1.     Calculate the square footage of your attic space. To do this, measure the length and width of your home.

For example: Width: 40 ft, Length: 30 ft (40ft x 30 ft = 1200 sq. ft.)

2. According to the National Building Code, you need 1 sq. ft. of ventilation for every 300 sq. ft. of attic space.

Divide your square footage by 300 sq. ft. to find out how much ventilation you will need, then round up to make sure you’re getting enough ventilation.

For example: 1200 sq. ft./300 sq. ft.= 4 sq. ft. of required ventilation (Intake and Exhaust)

3. Convert square feet of NFA to square inches by multiplying square feet of NFA by 144 (4.00 sq. ft. x 144 = 576 square inches of NFA needed)

4. To ensure your roof vents are drawing from your soffits, and not your other roof vents, we recommend that 50 percent of your ventilation should be provided by your soffits, and 50 percent should be provided by your roof vents (50/50). This means you should divide the number of vents by two. 576 sq. in. /2= 288 sq. in. of ventilation is required on the roof. 

We need 6 vents for our 1200 sq. ft. application if you are choosing a 50 square inch roof vent. (288 square inches divided by 50= 5.76 vents which rounds up to 6 vents)

It’s important to note that if your roof pitch is under 4/12, you will have to double the amount of ventilation that you need.

Duraflo offers a range of ventilation in different sizes, styles and heights. Check out your options here.


Previous Article
Ridge vent apparatus (Shingles fit inside)
Ridge vent apparatus (Shingles fit inside)

The next time you’re sitting beside the wing on an airplane, take a look out your window as you take off. Y...

Next Article
Common mistakes in mixed ventilation
Common mistakes in mixed ventilation

Ridge vent, tall vent, turbo vent, small vent—with so many vent choices out there, it’s hard to know which ...