CMU stands for Concrete Masonry Unit… AKA: a cinder block.
Refresher: we found over 100 brand new(ish) 8″ CMUs on our land… so we figured (since things seem to be falling into place with our home just the way they are supposed to) we might as well use them for our foundation! We got caught up in the inspection red-tape due to this change as we decided to veer from our city approved plans (constructing a monolithic slab built with filled concrete forms). We had to wait another day to have our newly engineered plans (changed to use our 8″ CMU’s for our slab walls) approved by the city and inspected again. This delay ended up being for the best as the first night after our footer pour was just below freezing (totally fine) and the second and third nights have been over 40 degrees! Perfection.
We will drill holes into our footer for rebar to be epoxied into. This will tie the CMU wall to the footer.
We will then build a CMU wall on top of our slab footer filling it with rebar and concrete and wet-setting in our fabricated steel plates to weld our containers to. Once the CMU wall is done we will put 2″ rigid insulation on the inside and outside of it and fill it with back-fill. We were considering using road-bond for our back-fill and tamping it down, but we can’t find it anywhere around here for sale so we are considering using recycled concrete aggregate as opposed to #57 gravel. It would be cheaper and yet another recycled item we could use as a building material.
We will then put 2″ rigid insulation on top of the back-fill to isolate the slab. We will put our 20mil vinyl (a couple of recycled billboards) vapor barrier between the rigid insulation (sitting on top of the back-fill) and below the bottom surface of the concrete, and we will set up some welded wire mesh over the vapor barrier. After everything is set with the slab, we will build our sonotubes rebar skeletons, and erect our sonotubes. Finally we will pour our slab and the sonotubes at the same time and wet-set the rest of our fabricated steel plates in the tops of the sonotubes. We will have finishers come in and make our slab all nice and smooth and our foundation will be complete!
Next step… buying the containers, shipping them to Asheville, NC. and chopping them up!