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Product Guide

How to Choose Insulation

We asked five builders for their go-to insulation strategies. Here's what they said.

Continuous exterior insulation is a familiar detail in high-performance houses, this one designed by Armando Cobo. The insulation reduces the transfer of heat through the building's framing. Photo courtesy of Armando Cobo.

Insulating a new house used to be a no-brainer. It was that step between installing windows and hanging drywall, when the crew spent a few days stapling fiberglass batts between studs and joists. In no time it was out of sight and out of mind.

That was before blower-door tests, performance metrics like LEED and Passive House, and a better understanding of air and moisture movement in buildings. What once was an afterthought is now rife with opportunities to screw up.

The type of insulation, and how it is installed, dictates comfort, energy efficiency, and building durability. And unlike many building materials, this one often is buried in places that are difficult and expensive to revisit. Whoever lives in the house is going to be stuck with the insulation decision for a long time.

The choices aren’t unlimited, but it may seem that way. In addition to ever-popular fiberglass batts, there’s blown-in fiberglass, cellulose, spray polyurethane foam, rigid foam, fiberboard, and mineral wool. Most of those come in more than one variety, and that doesn’t count more exotic options, like denim, wool, mushrooms, and hemp.

Where do you start? That’s the question we posed to five builders and designers who work in a range of climate zones. While their houses are typically designed to exceed code minimums, few construction budgets are unlimited. Spending constraints often have much to do with what kind of insulation is used—especially in a competitive market. Builders often find themselves looking for insulation packages that are affordable as well as effective.

Minimums outlined in the International Residential Code (IRC) are a place to start, but model building codes only describe required R-values of various building assemblies. How builders get there is another question altogether. For R-values and other details on specific…

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  1. Dan Kolbert | | #1

    Great piece - thanks!

  2. Tyler Keniston | | #2

    I agree, nice to see how real-world builders/designers approach this.
    The arguments against not considering embodied carbon seems to be little more than an unwillingness to do so. I won't fault one for such, given they are trying to run a viable businesses and build buildings that work consistently and go together predictably. But as the conversation continues, hopefully it becomes common-place for production builders to consider.
    The Maine based wood-fiber start up is worth keeping an eye on.

    1. User avater GBA Editor
      Brian Pontolilo | | #3

      Hi Tyler.

      I agree with you on the reluctance to consider embodied carbon expressed in the article. I have to wonder if it is inertia. For so long, builders focused on operational energy because we were taught that this is how we can make a difference with the work that we do. The news that embodied carbon may be more important to consider given the current understanding of climate issues is relatively new in the building industry at large. Hopefully it spreads and becomes an increasingly significant part of the conversation.

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