How Risky is a Moisture Barrier Sandwich?
I was discussing the building envelope details of a client’s 6,000 s.f. house under construction in Durham, N.C. so I could build an energy model. I was hired to help him right-size his HVAC system. We started with the roof and worked our way down to the basement. I’m still waiting on the construction details (as it is built), but I am concerned about the foundation walls.
The solid concrete walls have ‘Bone Dry’ asphalt WP membrane applied with ‘Bone Dry’ Thermal Drain board (R-10) over it on the exterior. The spray foam contractor (who claims he has been working with spray foam for 30 years…) recommended closed cell spray foam on the interior of the wall, which they applied one-inch of.
Assuming they’ve properly built the wall with a capillary break at the top and bottom, what risks are there in this assembly? I know some depends on the detailing around the footings, but what about the moisture in the not-yet-cured concrete? Is there enough to worry about?
Thoughts?
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Replies
Chris, nobody should own 6,000 houses.
As for the concrete, think about bridges or basement walls in contact with damp earth. Concrete can stay wet and be fine.