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Vapor barrier in crawl space: Placement relative to insulation blocks

Vapor barrier in crawl space: Placement relative to insulation blocks


Old 10-30-19, 10:25 AM
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Question Vapor barrier in crawl space: Placement relative to insulation blocks

This question concerns a1955 house, in Virginia (zone 4). Currently it has an open (ventilated) crawl space, the height of the crawl space is 2 ft. Don’t see any water standing in crawl space.

I am about to put a new vapor barrier in my crawl space, and face some question. I try to put the vapor barrier up the wall of the crawl space (to 2” below the wood sill, per Virginia building code [2015, https://codes.iccsafe.org/content/VR...3_Ch04_SecR408 ]). Eventually I want to enclose & condition the crawl space, but not now. I read that insulation blocks are required on the wall and on the horizontal space at least 24”. I found James City County has a memo with illustration: https://jamescitycountyva.gov/Docume...quirements-PDF . (FYI: I am not in James City County, but this sounds relevant.)

Sorry for a long background. Here is the question: If there is insulation blocks, where to put them relative to the vapor barrier?

* Option 1: Vapor barrier between insulation blocks and brick wall?

* Option 2: Insulation blocks between vapor barrier and brick wall?

Does the building code say anything in this regard? It seems like either way is acceptable, because I did not see the code require exactly one of them. Any recommendation/comment?
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Old 11-02-19, 12:16 PM
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You want the water/water vapor to be kept away from the insulation so put the vapor barrier on the walls and then the insulation afterward.

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