A lot of the defects we find as home inspectors involve installations where someone knows that something is necessary but either doesn’t know quite how to do it properly or tries to make something work that would be proper in another installation—-but not this one.
Take for example exhaust fans.
I see exhaust fans improperly terminated so often that it is almost rarer to find them “properly” installed—-especially in older homes. Take the roof vent in this first picture. This is a proper roof cap with a back draft damper—but it is not a type that is designed to sit on a flat roof—at least not “directly” on a flat roof.
One can see where roofing tar has been painted all around the vent to create a “curb” to prevent water from running into the vent and into the roof structure. In this case, the tar was not working and it was still leaking into the roof structure.
Sometimes I find them nicely installed.
In this next picture we can see the care the installer took to get the same type of cap raised high enough above the roof surface to prevent leaking.
It is not likely that water will ever get high enough to flood this vent. Whether wind driven rain will be a problem remains to be seen. There is a slight curb that the damper shuts against that provides some protection.
By Charles Buell, Real Estate Inspections in Seattle
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I’ve also seen water coming from a bathroom vent that was mylar and not insulated in the attic. Condensation collected in the venting and ran through the grill of the vent casing.
Bob, I would suspect that in your climate that would be possible. It is actually pretty rare to have condensation issues on the inside of vent ducting in the Seattle area. Having lived in the Syracuse area for too many years I am well aware of how much condensation can occur in vent ducting in really cold climates—very important to insulate the pipes very well, make the runs as short as possible and have good back draft dampers.