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  1. #1
    Join Date
    Jan 2012
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    Question Blocked ventilation question

    Firstly, thank you for taking time to read my problem and to consider any remedy.

    In 2010, I bought a home that was built in 1956 with no overhanging roof; hence, it has no soffits for venting. It has two large gable vents on each end of the roof North & South and two turbines. The house is approximately 1500 sf.

    In 2010, new cellulose insulation was sprayed into the attic high enough to adequately cover the joists. The cellulose insulation was sprayed all the way up next to where the roof edge and wall of the house unite.

    My problem: I started noticing severe cupping of my indoor ceilings this last summer, and the roof can be seen from the outside to be cupping along with numerous nail popping.

    Up in the attic, I pulled some insulation away from where roof and wall unite and noticed there is a 2-inch cavity between the wall and attic floor. I immediately felt cool air coming up and out of this gap.

    My question: is this cavity/gap a ventilation property of the house that has been blocked off by spraying in the new insulation and causing possible blocked ventilation? Alternatively, is there another reason for the sudden cupping and nail popping?

    Thank you for your generous advice.

  2. #2
    Join Date
    Jul 2004
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    To be honest, I'm not sure I'm grasping your verbal description of the house construction totally. So I'll just say this. There are two boundaries that need to be established in the building. One is the thermal boundary between conditioned (heated or cooled) air or surfaces and non-conditioned air or surfaces. The second consideration is the moisture barrier of the home. That's where moisture within the home is stopped. Now that moisture must at some point be allowed to escape or it would ultimately condense and you'd have moisture damage and/or standing water in places.

    It could well be that if the cellulose was added willy-nilly, one or both barriers were affected. That is to say that if the moisture barrier was established a the ceiling of the top floor rooms and from thence the moisture was to escape into the attic, then vented out the gable vents, you may have trapped moisture and are suffering the consequences. But just to be clear, I'm only painting with a very wide brush here as I'm not sure I understand the full construction techniques used on your home. Sorry. Maybe some pictures would help.
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  3. #3
    Join Date
    Jan 2012
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    Thread Starter
    Thanks skippedover

    Yes, I know I need to get hold of a better description of the house construction and I am working on that. The house has a brick covering and there appears to be a gap/cavity space between the inside brick wall and outer stud walls. From the attic floor, I can put my hand down between the two. Initially, I removed some fascia siding for gutter repair and then removed a section of fascia header from a rafter outlook end and found this opening.

    I hypothesize that crawlspace air is not able to rise up this cavity and not being pulled up the inside of the attic roof to adequately ventilate winter/summer air and moisture out the turbines and gables. This issue did not exist prior to adding the new insulation.

    What do you mean by “It could well be that if the cellulose was added willy-nilly.”

    Thank you Sir.

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