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Roof Ventilation: What’s it all about?

Roof Ventilation

Simply put, ventilation is basically holes in the structure that allows it to breathe. Air is sucked in the bottom and vents out the top. The “holes” are called intake and exhaust vents.

Intake vents bring air into the space (typically an attic) and are designed to keep out moisture, animals, and bugs. These vents are found on the underside of the lowest eaves on homes and work best with exhaust vents that are installed near the highest point of the roof.

Believe it or not, there are lots of homes that lack intake or soffit vents. Your home or business needs intake vents. Without them, the natural cycle of cool air entering at low points and warmer air exiting out the top cannot happen.

Since roofs can be very large, one set of vents (one intake, one exhaust) isn’t going to be enough to properly ventilate your home, which is why you’ll see at least half a dozen vents on even a small home. It’s important to have good air circulation under your roof because it can reduce cooling bills and extend the life of your roofing (tar and gravel, shingles, SBS system, metal roofing, EPDM, etc.).

Good ventilation is essential during the winter months. In Edmonton, we use a “cold roof system” where, instead of trying to retain heat in the attic, cool outside air is circulated beneath the roof. This eliminates ice dams, which are created when warm air from your nice cozy rooms escapes into the attic. This trapped warm air causes snow and ice to melt, which then flows down and refreezes when it reaches the roof’s eaves.

Ice dams are terrible for your roof! They cause water to leak through it, which can lead to rot and structure damage.

I saved the worst for last. If your roof isn’t properly ventilated, moisture can breed mold. Mold is especially bad for a home because it can get your entire family sick with Sick Building syndrome. If you have mold in your home, your only option is to have it removed.

What to do if you Find Mold in your House

You might be thinking, “Is my roof well ventilated?” Well, there are a few ways to find out:

  • If it’s wintertime, take a look at the underside of the inside of your roof. If you spot any dampness or frost, you need better ventilation.
  • Again, if it’s winter and your eaves troughs are full of ice or great, pointy icicles are hanging from your roof, you need better ventilation.
  • In the summertime, a way to tell is to touch your ceiling. If it’s hot, you need better ventilation because your attic has become an oven, slowly cooking your shingles and raising your AC costs.
  • Look at your roof. If you don’t see any (or possibly just a couple) vents, you need better ventilation.

A terrific resource that uses a mathematical formula to determine how many soffit vents you need for your home is found on Today’s Homeowner’s website: How to Determine how Many Soffit Vents are Needed using Math.

There are a LOT of different types of roof vents available, just check out Home Depot’s selection.
A few of the most common ones are Soffit Vents, Ridge Vents, Gable-end Vents, Turbine Vents, and Powered Vents.

St. Albert - Grandin Village Vents 2 - Roof Ventilation - Crest Roofing

This is a picture of townhouse roofs in St Albert, Alberta that we did a re-roofing for and it’s a good example of some of the types of roof vents.

You can see

  1. Furnace vent
  2. Exhaust vents – This is a vent that allows hot air out of the building, primarily used for bathroom or kitchen fans.
  3. Weatherpro Turbo vent – These vents pull air into the soffit vents in the structure and force it out with an electric fan.

The powered vents replaced existing Turbine Vents, which are wind-powered vents that draw air out from the attic space.

How is your home’s roof ventilation? Have you been getting ice dams or icicles? If you are, we can help fix your roof ventilation issues. Contact the Crest Roofing roof experts today!

7 replies
  1. Roofer Stevie
    Roofer Stevie says:

    Great article, there are many houses I see in the Toronto area with ice damming. Very detrimental to the roof and home, the public needs more articles like this to be aware of the problem.

Trackbacks & Pingbacks

  1. […] melts the snow on your roof, the best way to prevent them is to have a well insulated attic with good ventilation. The idea is to keep the area under the roof cool so that snow on the roof doesn’t […]

  2. […] Want to know more about the fascinating topic of roof ventilation? Read Roof Ventilation: What’s it all About? […]

  3. […] exception is your soffit vents, which are essential for your roof’s ventilation (Read more about roof ventilation here. We make sure your soffit vents are left clear because your attic needs to have proper air flow. […]

  4. […] better and last a long time. We featured the Grandin Village Townhomes in an article we wrote about roofing ventilation, and you can read it […]

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