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Proper Roof Ventilation

Most people know that their roofs need to be ventilated, but you might find yourself asking these questions: What is the purpose of ventilation? What does proper ventilation look like? How do I know if my roof ventilation is functioning? What are signs that my roof isn’t properly ventilated? And finally what are my options and how do I pick? Hopefully this article will answer those questions for you.

Heat and moisture attack and destroy the home; besides the weather, we create humidity with our day to day activities such as showering and cooking. If not removed, heat and moisture can cause your paint to peel, your insulation to become wet and flat, mildew and mold, rotting wood, crumbling shingles, and higher utility bills. Ventilation adds longevity to your roof system, which is why all shingle manufacturers include it within their warranty; you don’t want to void that!

Appropriate ventilation keeps the air flow going throughout your attic. The air flow pulls the heat and moisture out of your attic. In the summer, ventilation keeps your attic cooler- this is desirable for 2 reasons. First and most obviously, your AC bill will be lower because your home won’t retain heat. The second reason requires a quick explanation about shingles. The granules on the outside of your shingle aren’t there just to make your house look pretty but it protects the fiber layers underneath (the heart of every shingle). These granules have been formulated to withstand elemental damage such as hail and heat. During the summer months, the shingles cannot protect the underneath side from heat. They just weren’t made for that. Keeping your attic cooler in summer through ventilation guarantees that the shingles won’t cook from the inside out.

Mold in the Attic
Ice layer in the attic

There are many signs that your roof’s ventilation is not adequate. Without climbing into your attic, you can tell that it isn’t functioning correctly if your house won’t cool in the summer.  once you are in your attic, look up; if you see mold you know that moisture is not escaping. In winter this moisture freezes and in extreme cases becomes a sheet of ice; as this ice melts you essentially have rain in your attic. This will ruin your insulation and your ceiling drywall. If your ventilation was installed incorrectly, the exhaust vents turn into intake vents which will suck snow into your attic.

Exhaust vents must be at least 3 feet higher than the intake for the air to be pulled continuously.

Knowing your ventilation options go hand in hand with knowing what is needed. Proper ventilation is 50% intake and 50% exhaust, many installers go into a job that needs better ventilation will just add more exhaust vents but if it can’t be exactly 50-50 it’s better to have more intake than exhaust. Vented soffit is where you get your intake.

The exhaust vents need to be on the same side of the ridge so they don’t turn into intake vents.

In the same attic body, keep all exhaust vents installed at the same level, same side of the ridge, and same style of vent to ensure that the exhaust vents don’t turn into intake vents. Venting options include but are not limited to box vents, ridge vents, and turbine vents (also known as whirlybirds). Ridge vents are better than box vents because they are placed at the peak of your roof where heat rises to. The tricky part about ridge vents is having the proper ratio which I’m not going to go into the crazy equations, but just know that your contractor should be aware of this to get proper air flow with ridge vents. Whirlybird vents are great because they actively pull out the heat while all other ventilations just rely on the heat to create the flow.

Different styles of exhaust vents.

Happy Venting!

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