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Community and Q&A

Odors from roof cavity

dpbos | Posted in General Questions on

This is an unusual situation. I live in an old mid-rise brick building with a flat black rubber roof which was replaced 4 years ago. Ever since it was replaced we’ve had a strong adhesive-like chemical odor in part of our unit (top floor) during the warmer months, especially on hot sunny days but not exclusively. Bad enough that we avoid the room. Had the air tested and there are elevated VOC levels when the odor is present. We’ve gone through several rounds of trying to figure out the exact source of these fumes but without getting really invasive/destructive it’ll be all but impossible to find it. So, we’re going to try ventilating the roof just above our unit, in hopes of changing the air pressure so any nasty air goes out rather than in.

My question is: in order to be as sure as we can that this will be fixed, are we better off installing solar powered roof turbines, or passive ones? Do they still operate well enough passively on cloudy days? Or if we install the solar vents and it turns out they’re overkill, would they still work well passively if the fans were turned off? For red-tape reasons, it’s critically important that we fix this on the first try.

Also, I know powered vents can suck some air-conditioned air out of the interior and thus decrease efficiency: this is of FAR less concern to me than making sure the fumes aren’t getting into the interior.

I know there are other things to do – better insulation, vapor barriers, etc. – but for various reasons all other options have been decided against (too long to explain). Just want to find out whether we should spring for the powered vents or plain unpowered turbines.


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  1. Expert Member
    BILL WICHERS | | #1

    If you’re stuck with active ventilation as a “solution”, I’d go with powered ventilators. The reason is that they’ll be more powerful, and YOU can control them instead of nature. You may find you need them to run at night or on calm days, for example, when solar or wind-powered ventilators wouldn’t be able to run.

    You should really look into air sealing though. My guess is you’re smelling roofing sealant that’s leaked through gaps and/or punctures in the structural roof. You’re smelling it due to air leaks. Another thing to check is to make sure your makeup air intake (assuming you have one) is located a distance away from whatever is smelly so that it does suck in “fresh” smelly air, which could potentially happen even after you’ve had power ventilators installed in the attic space.


    1. dpbos | | #2

      Thanks for the response Bill; after a discussion with the roofer, I think we're going to go with the passive turbines for now -- partly because we don't want anyone to have to come into our unit due to the pandemic -- and that if it turns out we do need power, the roofing work (cutting the holes, flashing, etc) will already have been done and it's only a matter of unscrewing the passive vents and replacing them with powered ones, plus having an electrician hook up the power and a switch indoors.

    2. dpbos | | #3

      Oh, and re: your second point -- we talked about air sealing; it's a 120-year-old brick building, and it seems that trying to really seal it up would require some quite major work, so that's not in the cards at least at this point.

      Thanks again!

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