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Community and Q&A

Thermasteel Pros/Cons + Flame Retardants Used?

Highgrove | Posted in Energy Efficiency and Durability on

I am developing several buildings on a remote farm in North Carolina where subs and skilled labor….or any labor can be very hard to come by. I have a full-time builder onsite and 1-2 skilled laborers so when I came across it seemed like a miracle product:

– They claim that one product is the structure, the insulation, the sheathing, and the vapor barrier all in one. This all comes with a 50+r-value and they provide roof and wall panels! All of this at about $10 per sf of surface area, delivered.

– The biggest attraction to me is the DIY aspect and light weight that would allow my onsite team to knock out all of the framing an insulation on a structure in a few days.

I had planned a more complex structure using plywood, prosoco WRB, exterior rockwool insulation, interior rockwool insulation, and 2×6 construction. This method is both an expensive and labor intensive application due to the many “layers” that require another pass.

I have two reservations that I would appreciate feedback on:

1. I generally am averse to foam for health reasons. In this case the foam is EPS, totally inert but also highly flamable. Thermasteel says that theirs is not flamable due to the addition of a flame retardant. Despite numerous emails requesting to know exactly what the flame retardant is, they have danced around the question and so far have not given me a direct answer. Does anyone have documentation on what they put in it? No chemicals are good, but there are some that may be a total deal-breaker!

2. My 2nd concern is that Thermasteel seems to get very little attention on forums such as GBA. With the seemingly incredible r-value, DIY option, and other benefits, why is there hardly a mention on this forum despite Thermasteel having been in business since 1971? Would love to hear from anyone who has used it, especially more than once!

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  1. rockies63 | | #1

    There's this website about a guy who built with Thermasteel.

    And this guy on Youtube who used them for his house.
    Part One.
    Part Two.

    It looks like a good product but I notice that there is no metal skin on either side of the panels - it's more of a metal "bracing system" to which I guess you'd have to attach exterior sheathing and interior drywall.

    There are SIP panel systems that have metal skins - that would enclosed any foam and prevent off-gassing. Some even have Rockwool interior cores. These ones are for walls only - not roofs.

    These metal SIP panels are "The Only Steel SIP ICC -ES Recognized and FCC Approved for Use as Structural Walls and Roof".

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