Do I need an exhaust fan in an unfinished garage?
Hi all,
Building a tight house and planning an exhaust-only ventilation strategy, depending on the blower door test results. However, we are having an attached garage, so I’m worried about air quality with an exhaust-only strategy.
On the other hand, the garage is going to unfinished. I will have to finish the shared wall between the garage and the house, but the rest of the garage can be unfinished. This includes no ceiling, exposed roof trusses, all he way up to the roof deck. I am planning gable vents for the roof ventilation strategy.
Will the gable vents provide enough passive ventilation in the garage to make powered exhaust unnecessary, or is it sill recommended to have an exhaust vent installed?
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Replies
Clay. This article by Allison Bailes addresses your concerns: https://www.greenbuildingadvisor.com/articles/dept/building-science/don-t-let-your-garage-make-you-sick.
Many of the attached garages in my community are equipped with bath fans on manual switches. (I lived in one unit for a couple of years.) An automatic switch would have been better, as Allison explains.
Clay,
The type of garage you describe, with no ceiling and gable vents, doesn't need an exhaust fan.
However, when a house includes an attached garage, it's always essential to pay very close attention to air sealing details on the wall that separates the house from the garage. I would certainly verify the airtightness of this wall with a blower door or a theatrical fog test.
It's also important to make sure that the door in this wall is adjusted properly, and is equipped with high-quality weatherstripping.
Thanks Martin. That's what I was hoping.
And thanks for the reminder on the air sealing. We are taping the seems of each layer (osb and both layers of insulation). Do you think that is enough or is there other sealing we can do? I was thinking about an outswinging door so airflow from the garage to the house would pull it tighter to its weatherstripping, but there isn't enough room to swing the door out into the garage.