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Community and Q&A

Concrete SIPs and Air-Sealing

voldie997 | Posted in Green Building Techniques on

Hullo All,

I’ve been a long time lurker here. Thank you all for all the information that you share in these forums. There is so much to learn and I’m indebted to all your work.

We are building a home in Santa Clara County CA (Climate Zone 3C). I have decided to use concrete SIPs (e.g RSG 3D, Innstruct) to build our house. This is basically an EPS foam block covered on both sides by concrete. The goal is to add additional fire resistance to the building, but I also want to use this opportunity to build a passive, air tight, energy efficient home. I hope that I can connect with other folks here who might have used this building system.

This video provides a good description of this system for folks who might be unfamiliar with it.

Coming to my question: (first of many, I expect)

This will be a slab on grade foundation. What is the best way to ensure a very good seal between the flooring and the walls. I was thinking that we might employ a tape of some sort which can stick to the concrete on the floor level and the steel cage on the wall before the shotcrete is applied. However this does not seem very clean or elegant. Any other experiences or ideas?

Thank you!

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  1. orangutan_librarian | | #1

    whats the benefit of that method over icf?

    1. voldie997 | | #3

      The foam is on the inside, covered with concrete. This is better in areas with termites. There is exposed concrete thermal mass in the interior of the home, this helps regulate an even temperature inside the home. I'll cover it with plaster on both sides and be done, no more drywall and hopefully less expensive.

  2. GBA Editor
    Kiley Jacques | | #2

    Your wall assembly puts me in mind of a pretty wild panelized wall system I learned about when working on this story: A Holistic Approach to Housing. It’s a 28-ft.-tall by 18-ft.-wide gable wall with five windows, 12 in. of EPS foam (outboard of the structural interior concrete wall), and magnesium oxide board siding (selected because it is noncombustible, affordable, less energy-intensive in production than fiber-cement board, and it holds paint well). It might be interesting to you. If I recall correctly, the air-sealing strategy was AeroBarrier.

    1. voldie997 | | #4

      Thank you for your reply. I'll certainly be looking into Aerobarrier. I have not seen any uses of Aerobarrier in concrete buildings, but there are not that many concrete buildings to start with :) .

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