Would plaster in a vented, unconditioned attic be an issue?
Stephen Horvath| Posted inGreen Building Techniqueson
I have a friend who is putting a new roof on an 80-year old house in Pittsburgh. She’s experienced problems with ice damming in the past and is considering adding a ridge vent along with the new roof. The attic is finished with a hardwood floor and plaster/lath ceiling. They recently added insulation in the attic floor.
Would the plaster need to be removed if a ridge vent were added?
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Replies
Stephen,
Q. "Would the plaster need to be removed if a ridge vent were added?"
A. It depends on three factors: the details near the eaves; whether or not there is any insulation or blocking between the plaster and the roof sheathing; and the details near the ridge.
A ridge vent only works if there is a clear channel that allows air to flow from the soffit vents to the ridge vents. If the plaster doesn't interfere with that air channel, then the plaster can remain in place.
Considering the ridge vent has a clear-channel from the soffits to the ridge, would there be any mold or other environmental issues with having the plaster located in an unconditioned space? I'm sure there is no other air or vapor barrier between the roof sheathing and the plaster since the plaster was put there so long ago.
I'm guessing we'd probably have to take down some of the plaster anyway in order to check the space between the soffit and ridge.
Stephen,
Q. "Considering the ridge vent has a clear-channel from the soffits to the ridge, would there be any mold or other environmental issues with having the plaster located in an unconditioned space?"
A. No.