The reason that the final inspection on roofs now includes a venting check is that no one used to do it. There are many homes with almost no venting. That means heat and moisture get trapped in the hot attic with no airflow. Hot, dark, and damp are great for mold.
Today, most contractors still don’t understand the basics of venting. Builders simply throw vents on the top of the roof to accomplish venting. Inspectors aren’t quite sure so they see the vents and it passes.
The bottom line is you have to have more intake (at the bottom) than outflow on the top.
Think of the top vent as a vacuum sucking the air out of the attic. What happens if you don’t have the same or more intake venting on the bottom of that attic space?
The air gets pulled from somewhere. That means your expensive new solar reflective roof is pulling air from anywhere it can – your recessed lights, fans, or any other intrusion that allows air to pass. Basically, your roof vents are pulling the air conditioning right out of your house and into the sky. The savings from the thermal reflection of the new shingles gets lost when the cooling is drawn from inside the house.
That’s the good news if the air in your attic is moving through most of the attic. Dead spots where the air is hot, dark, and damp. This is ideal for growing mold, not for breathing. Your attic should act as an air ventilation system for your home. Proper venting keeps the house comfortable and healthy.
Remember, venting is strategic. Do your roofers understand that?
PS You can remind them by looking at the location of the bottom vents and the ratio to the top vents. An easy ratio is 55% bottom / 45% top.
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