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Community and Q&A

ICF’s vs SBC with outside insulation. Dry Stacked Surface Bonded CMU

mikeolder | Posted in General Questions on

Hello everyone.

I was wondering if anyone had experience with SBC? Looks very DIY friendly.  I planned on 2×6 walls with the Bonfiglioli approach inside my new house, but I live in tornado alley and I may have more time on my hands than I had planned on soon.

Some people have mentioned SBC walls could not be as strong or monolithic as ICF, but that’s not entirely true imo. If you used “speed blocks“, or open ended H blocks, the poured concrete would flow behind all the cmu seams similar to ICF.. Yes, there’s a big web in the center of a H block for rerod, compared to many plastic ties with the ICF which could leak.. But I plan on insulating the outside with rock wool, which above grade would then be sealed with a WRB, and below grade with a rolled on bituthene and peel & stick before 2″ of rockwool. So I’m not very concerned with this one web per block possibly leaking, or how much less strength CMU vs ICF is when installing a bond beam in every course..

What I’m more concerned with is the squareness and size irregularities of the blocks even if its only 1/16″. This inaccuracy will multiply with each course and was brought up by I think Lynn Graves at Sort of why some tile are rectified or precision ground to a consistent size for narrow grout lines. And the reason they used mortar lol. But adhering the blocks may eliminate the racking of inaccurate blocks.

So I’m not touting dry stacked and surface bonded is perfect for diy, but pretty close.. For the healthy retired diy type with allot of time on their hands, SBC might be a method to save allot of money and has thermal mass built in. What’s all that thermal mass worth? Over 10% of your energy usage according to what Ive learned, but not with ICF due to the interior foam.. Especially if a block adhesive was used and someone manufactured a true 8×16 H block specifically for SBC.. But wouldn’t you have to run your utilities inside the cmu wall and use the surface bonding cement as the interior stucco/plaster finish to allow heat to readily flow? And the frost footings would have to be insulated to not act like heat sinks etc..

Anyway, has anyone had experience, thoughts or considerations with SBC?


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