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Community and Q&A

Cold Climate Crawl Space Ventilation

user-6445625 | Posted in General Questions on

Hey folks
I know the consensus here is to NOT vent a crawl space to the outside through the foundation wall, which I agree with, but I wanted to check in to see, aside from the building science, where the code permits no venting. We are in NY State in climate zone 5A with a crawl. Are people referring to code section 1202.4.2 Ventilation in Cold Climate, which permits a sealed crawl as long as it has mechanical ventilation tied to the house above?

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  1. Expert Member


    IRC Section 308.3, Unventilated Crawl Spaces

    "This paragraph makes provisions for situations in which builders and homeowner prefer to omit vents in crawl spaces, usually because they wish to prevent thermal heat loss or to prevent insects and other vermin from gaining access to the crawl space.

    Builders are now allowed the option of creating non-vented crawl spaces, provided they follow the following procedures:

    Mechanically circulating air should be established between the upper conditioned area of the home and crawl space.
    The air-circulating device must move at least 1 cubic foot of air per 50 square feet of crawl space area.
    The crawl space floor area must be completely sealed with a vapor-retarding material.
    The edges of the vapor retarder must be lapped up against the inner foundation walls. Overlapped separate sheets must be lapped at least 6 inches. The seams must be sealed.
    All crawl space walls must be insulated to appropriate R-values for the regional climate."

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