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Vaulted ceiling ventilation


fyrmnk
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Hi all. I inspected a 40 year home with a 2 year old comp roof with a full vaulted ceiling throughout. No vents anywhere high or low, and some spongy sheeting when walking. I recommended further evaluation of need and type of ventilation.

I don't see too many full vaulted ceilings. What is the general requirement for venting the underside of the decking? Vapor barrier/insulation gap below decking(not accessible to view)? Any other input? Thanks.

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I don't know how ya'll do it up North. Most builders here will run baffles up the rafter bays, vent the blocking (if any) and continue the baffles right up to the main attic. Soffits on the bottom and what ever type of upper attic exhaust venting that particular builder uses.

The baffles, if installed correctly, should give you an inch or more of space. Just food for though because we're in a hot/humid climate so your needs may be different.

Donald

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Thanks for the replies. There is no attic at all, it is fully vaulted ceilings.

The home is 40 years old. No inspection was needed after the roof replacement 2 years ago. It's unknown whether there was venting before the tear off and re-roof. Thanks again, any other input is appreciated.

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Originally posted by fyrmnk

Thanks for the replies. There is no attic at all, it is fully vaulted ceilings.

The home is 40 years old. No inspection was needed after the roof replacement 2 years ago. It's unknown whether there was venting before the tear off and re-roof. Thanks again, any other input is appreciated.

Even if there is no attic, a 1" air space is currently required between insulation and roof sheathing. Without destructive investigation, you cannot know what the current air space is between the insulation and sheathing. My experience is that a 40 year old house roof was not adequately ventilated when built and there are likely to be concealed problems such as rot, mildew, and/or mold.

You asked what are the ventilation requirements, not what were they when the house was built. I would not refer to current code requirements, just good construction practice and potential problems caused by inadequate ventilation.

Just CYA and write about the possible concealed problems that may not be discovered within the scope of your inspection.

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Originally posted by Steven Hockstein

Originally posted by fyrmnk

Thanks for the replies. There is no attic at all, it is fully vaulted ceilings.

The home is 40 years old. No inspection was needed after the roof replacement 2 years ago. It's unknown whether there was venting before the tear off and re-roof. Thanks again, any other input is appreciated.

Even if there is no attic, a 1" air space is currently required between insulation and roof sheathing. Without destructive investigation, you cannot know what the current air space is between the insulation and sheathing. My experience is that a 40 year old house roof was not adequately ventilated when built and there are likely to be concealed problems such as rot, mildew, and/or mold.

You asked what are the ventilation requirements, not what were they when the house was built. I would not refer to current code requirements, just good construction practice and potential problems caused by inadequate ventilation.

Just CYA and write about the possible concealed problems that may not be discovered within the scope of your inspection.

Is there any possibility that it is one of the blown in insulations that do not require venting?

Pete

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I'm not aware of any blown in insulations that wouldn't require venting. Icynene, if properly applied could be used in an unvented attic with a meticulously installed vapor barrier on the bottom of the ceiling joists with excellent detailing at the wall to truss or rafter junction. Given the age of the home it's far more likely that the vents were omitted during a re-roof or never existed

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