Preventing Ice Dams: Ventilation Part 1
Monday, February 20th, 2017
How to Tell if You Have Adequate Roof Ventilation in Your Soffits
Proper roof ventilation is an essential component of ice dam prevention. It is possible to get ice dams even when you have normal or even above average insulation in your attic. Passive heat loss will build up in your attic due to the stack effect (tendency for heat to rise). Therefore it’s important to let the attic breath so that warm air can be evacuated properly. Here is a quick way to check your attic for proper soffit, or eave ventilation:
Go up into your attic and look around in the dark. Here is what you should see:
If you can see a lot of light through your eaves (A) you have half of your attic ventilation addressed. The other half is the ventilation up near the peak of the roof either in the form of box vents mounted to the roof deck or an open ridge vent along the majority of the ridge. It’s common to see the eave ventilation clogged with blown in insulation. Another common hindrance to proper eave ventilation is compressed or collapsed air chutes. This Eden Prairie home had problems with air-sealing and attic ventilation. We fixed the problems.
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