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Contractors, expertise, and details for exterior rigid foam on roof

philray | Posted in Green Building Techniques on

Zone 5a, Southest Michigan. Based on the article Combining Exterior Rigid Foam With Fluffy Insulation, I’d like to have two 2″ layers of polyiso installed on the exterior of the roof sheathing when we re-roof our 1958 tri-level (along with fluffy insulation inside). We’ll likely do some additional envelope and mechanical improvements, but first priority is the roof.

I’m having trouble finding the right trades or expertise on this. Am I looking for a roofer, an insulation specialist, or a general builder/renovator?

Local builders and renovation contractors with a reputation for quality and/or green practices seem to be working only larger jobs (>$100k). Insulation contractors in the area seem to be all about spray foam. One particularly reputable roofer I talked with seemed somewhat open to working with rigid foam, but also made it clear that they’d be out of their area of expertise. A related concern is getting the details right. There’s a poorly implemented chase that’s been added on between two sections of roof (to carry a/c ducts in the unconditioned attic), and I want to get both the aesthetics and the continuous air barrier right at the eaves. I want to do this right, but I haven’t been able to connect with the right expertise yet. Advice?

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  1. peterbauer | | #1

    go here for an option. you get insulation and roof cladding.

  2. GBA Editor
    Martin Holladay | | #2

    You have accurately described the situation for any homeowner looking for a contractor to do this type of work. I wrote about the problem you describe back in 2009 (see "Roofing and Siding Jobs Are Energy-Retrofit Opportunities"), and the situation hasn't gotten any better since then.

    One option is to consider installing nailbase. (Nailbase resembles SIPs, except with OSB on one side instead of two.) You might contact a nailbase manufacturer to ask about contractors in your area who have purchased or installed nailbase.

    You might also look for a contractor with experience installing SIPs. Such a contractor might be willing to undertake a nailbase installation job.

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