Quote:
Originally Posted by Accidental1
It's my understanding that venting through the soffit isn't a great idea either. I believe the soffit tends to draw in outside air so if you vent your humid bathroom air out the soffit it just gets drawn back into your attic. I've had direct experience with this on our house in Indiana. The sheathing inside the attic directly above the soffit vent showed signs of mold so I had the vent re-routed through the roof.
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I’ve vented ceiling fans through the soffit before, but always with a hole in the soffit letting out the expelled air. You are right that just blowing it into the soffit space could cause a moisture buildup, but of course it is blowing air that is 40-50% humidity, unless it is venting after a shower, while the air being sucked through the soffit into the attic is often 80% humidity and sometimes more.
Yesterday I went up to my attic for the first time. I discovered that the soffit vents are working well all around the garage, but they seem to be blocked by insulation around the rest of the house. However, it may be that the air through the garage soffits are enough to maintain air circulation in the attic, what with two air vents at the top of the roof and a fan with solar panels on top of it.
I also discovered that workers over the years have pushed away the insulation over the bottom chords of many of the roof trusses, leaving them exposed. There seems to be, at present, at most six inches of insulation, with only four inches of wood where the trusses are. (In the home I built in Pennsylvania, I had 16” of blown-in virgin fiberglass.) I suspect that adding more might decrease cooling costs, though the payback may be several years.
Thanks for the info about the venting.