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Attic question


Mark P
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This house has cathedral ceilings throughout, except for this small attic area above the master bedroom. As you can see it has OSB attached to the rafters and laid out as flooring. It is around 3’ high in the center, so it won’t ever be more than a storage area. There is no insulation under the flooring and I could not see between the rafters. There is no ventilation to the outside; there is one vent between the attic and the living room. I have not come across this before and would appreciate your thoughts...

Thank you,

Mark

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Hi Mark,

Is there a possibility that this is a SIPS (Structural Insulated Panel System) house or are there definitely rafters with the OSB attached? A SIPS structure has the insulation between inner and outer OSB panels, so you wouldn't be able to see any insulation and there wouldn't be any on the ceilings below the attic space.

OT - OF!!!

M.

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Hum, That give me some food for thought. I guess it is a possibility, but without removing a section of OSB I can't tell. Are SIPS houses not vented? The house was built in 1984, if that offers any clues? It has no roof/ridge/gabel/ vents at all since all the ceilings are cathedral.

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Nope,

SIPS homes are not vented. To get around the need for roof ventilation they sometimes use vented nailbase insulation over the SIPS. The technology has been around since the 80's but didn't really start taking off until the 90's.

Some folks living in SIPS homes - in heating climates especially - have experienced problems with the envelope rotting due to poorly sealed joints between panels. Warm-humid inside air moves up through poorly sealed joints and then condenses inside the joint near the outside face of the membrane and the moisture soaks into the outer face of the panels and causes them to rot. A bunch of folks up in Alaska had serious problems with that back around 2000. The situation was so bad that the SIPS industry association had to get involved in diagnosing and helping to design fixes.

That's neither here nor there though until you determine whether it actually is a SIPS house. For all you know at this point, it could be a conventionally built home with fiberglass in the roof plane and no ventilation at all, in which case, I'd be very interested to see what the condition is of the roof decking.

OT - OF!!!

M.

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