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Community and Q&A

Rockwool airgap

FreedomForward | Posted in Energy Efficiency and Durability on

We are building an air tight home that has zip board on eaves and roof.  Everything is taped and caulked in.  We want to do a conditioned attic and are using rockwool in between rafters.  Rockwool says we need an air vent behind insulation.  What is proper way to install to prevent moisture?  We are installing fresh air return and have dehumidifier.  We don’t have ridge vents if course, wanting to do like Rissinger projects.   Thanks!

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  1. Expert Member
    Michael Maines | | #1

    If you hadn't already installed the roofing, you could over-vent the roof, letting moisture work through the sheathing to be evacuated in a venting layer under the roofing. But in your case it's too late for that. If you don't want to vent your roof, you need to use spray foam.

    What climate zone are you in? In warmer climates, open cell foam is code-compliant and some experts consider it to be safe from moisture accumulation. In colder climates, you need closed-cell foam or a mix of closed-cell foam and mineral wool (or other fluffy insulation).

    More info here, and at the related links:

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