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Moisture on rim joist


CHI
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Not sure what would be the cause of this. New construction, cement siding. Approximately 45 degrees outside, lows overnight in the 30's. The rim joist and sill were soaking wet at nearly all locations in the crawl. You can see water stains on the foundation wall at several locations. The ends of the insulation were dripping wet when pulled back. I'm assuming it has to due with a lack of vapor barrier at the exterior?

Anyone got the answer??

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That's exactly where you'd find condensation in most finished basement houses in a heating climate if you were to cut into the ceiling and explore the rim joist area. An alternative possibility is rain that's leaking in at the sills. Did the siding extend below the sill or did they stop it right at the sill where moisture draining off the drip edge of the siding will wick directly into the sills?

Found exactly the same thing two weeks ago on the rim of a crawl behind a concrete porch without any vents.

ONE TEAM - ONE FIGHT!!!

Mike

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Yeah,

Fix the barrier, make sure you don't have any windows or doors leaking into the walls and make sure the insulation is against the underside of the floors and not flush with the bottom of the joists with a two inch space above it for warm moist air to migrate into from above and head straight for the cold rims.

OT - OF!!!

M.

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Tell them to go to the Building Science site and study the concept of "Vapor Diffusion" and that, once they understand it, fire the insulation sub they're using and bring in another to get all of the insulation under all of those homes pushed up against the underside of the floors where it's supposed to be. Look at your first picture - that tells the tale.

ONE TEAM - ONE FIGHT!!!

Mike

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