Roofing Ventilation 101

How do you calculate and plan roofing ventilation 101 and why is this necessary? Well, there are actually quite a lot of benefits when your roof has sufficient ventilation. First and foremost, proper roofing ventilation will increase your roof’s lifespan. Blistered shingles, Ice dams, and frost in the attic are sure signs that your home is suffering from poor ventilation. In fact, proper ventilation can save you thousands of dollars on roof repairs!

Poor ventilation can cause damming (where ice builds up on your roof). This can create significant damage to your roof and decrease its lifespan. Ice damming is a result of heat in your attic combined with the sun’s heat, which causes snow to melt on your roof. When the melted water gets to the edge of the roof there will be a possibility that the roof will refreeze.  This can compromise not only your roofing system, but the whole structural integrity of your attic. With proper ventilation, hot air will be effectively removed from your attic so that it doesn’t melt the snow on your roof.

Another benefit of good roofing ventilation is that it helps lower energy costs. When the outside temperature rises, people go indoors to keep themselves cool. When your roof is properly vented, it will allow heat to dissipate. This means your AC’s workload will be reduced… resulting in a lower power bill.

There is a wide range of ventilation systems; however, there are only two main methods of ventilation: mechanical and natural ventilation. Natural ventilation uses wind to push the rising hot air out of a vent as exhaust.

Regional factors like climate, house style, and code requirements vary from city to city. Each system is specially designed to take all that into consideration. 

Sometimes a combination of vents should be used and high and low vents should be installed for proper ventilation. High vents act like exhaust vents while low vents should act like intake vents, but it depends on the winds from the particular climate.

Crooked turbine vents are the ventilation systems that spin from the wind. They have to be installed perfectly level in order to properly function with the wind. These vents do a good job of pulling the hot air from inside of the whole house as long as the attic is sealed properly.

Step 1 – Use a tape measure to calculate the dimensions of the attic. If your attic spans the entire area of your house then it will be easier for you to measure the outside of your house. Let’s assume that your attic floor has an area of 1200 sq ft (30×40 ft). 

Step 2 – In order to find the appropriate venting needs of your attic, you’ll need to divide 1200 (floor area) by 150. The answer will give you your roof’s venting needs.

Step 3 – Your next step is to measure your roof ridge’s length. Multiply the length by 18 square inches. The answer is the amount of venting for a ridge provider per linear foot.

Step 4 – Calculate the dimensions of the soffit vents and then measure their areas. Make sure you have sufficient numbers in order to have extra venting for your attic. You can usually find the square footage of a soffit vent on the label. 

For example, if you use a 6×12 rectangular vent then it means you’ll need 10 of those since each one has around ½ square foot and you have to match it with the ridge vents.

Step 5 — Next, use a ruler and marking pencil to measure and mark those dimensions out onto the roof.

Step 6 — Use a jigsaw or reciprocating saw to cut along your measurements. Make sure to cut through shingles and wood underneath.

Step 7 Next, use a pry bar to loosen shingles and remove the section.

Step 8 Apply a thick layer of caulk to the flange of the vent (the bottom)

Step 9 After that, slide the vent into the surrounding shingles. The bottom part of the vent should be left exposed. Rest it on the shingles below.

Step 10 — Hammer in nails every few inches to make sure the vent is secure

Step 11 — make sure there are no loose shingles around the vent. If there are, hammer them down with some nails.