Thoughts on Framecad cold formed steel for house framing?
Hello,
I’m planning to build a small two family house in upstate NY, zone 5. I have plenty of time to plan this and I’ve looked at modular methods and panelized methods.
I know this may raise ‘green’ hackles but I’m quite interested in framing the house with the Framecad cold formed steel system. Steel is 100% recyclable, and doesn’t creep or rot. The Framecad licensee can pre-build the wall panels at the factory which is ~ 75 miles from my job site.
I would apply 3 or 4 inch continuous insulation outside the sheathing and WRB so I’m not too concerned about thermal bridging of the steel. Also, the shear bracing of the walls can be done entirely with flat ‘X’ shapes of steel, meaning I would not need plywood or OSB sheathing, I could go straight onto the steel frame with Dens-Glas or equivalent.
Thoughts/opinions? I don’t know the pricing yet . . . .
Paul White
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Replies
Steel is recyclable. The problem is that its large global warming emissions--1 to 2 lbs of CO2 for every pound of steel--is emitted entirely in the present, when our climate can least afford it. That's for recycled steel. The same conditions that lead wood to rot will lead steel to rust. The exterior insulation you are likely considering is foam-based, another climate disaster. You can certainly build a house out of steel and foam, but you can't call it environmentally responsible.
Michael thanks for your responses.
As to the insulation, I'm confused. Haven't I seen many details and discussions on this GBA in which EPS and XPS foam is featured - under slab, outside basement walls, etc?
Perhaps I missed something?
Please clarify.
Instead of foam, would mineral wool boards be environmentally responsible?
thx,
P. W.
Below grade, EPS is a reasonable choice. Above grade there are many other options. Plenty of people choose to build with piles of foam, steel and concrete, but that doesn't mean it's necessary or good for the planet. Mineral wool is roughly comparable to rigid foams in terms of CO2 emissions; it takes a lot of energy to melt the rocks that make it up. Cellulose and wood fiber are two very low-carbon insulation materials that work extremely well, when designed and installed properly.