1,810 square feet building footprint, 6 inches thick. 2 pours. Roughly 66 yards total. Starting November 2017.
$21,365 for slab, footers, concrete pumper (twice), fibermesh, hot water and other accelerators (~freezing during pour), blankets, saw cuts, foundation bolts, curing sealer, and some rebar in the footings. Concrete guy also ordered a richer mix due to the cold.
Dirtwork was about $10,000; excavate to 30 inches, bring in and compact fill, bring in water line, and connect to sewer. Fill ranged from 2 to 18 inches over the original ground level.
I provided steel mesh to tie PEX for hydronic heat, 2" insulation for slab, and vapor barrier. I installed the vapor barrier, slab insulation, steel mesh, tied the PEX to the mesh, and put the mesh on "dobies" (pieces of cement pavers left over from another project).
Rough plumbing under the slab for a bathroom and a sink was $1,760 and a survey for lot line setback was $810.
That's $33,935 excluding the stuff that I provided. I probably provided less than $4,000 in materials. 33,935/1,810 = $18.75 per square foot.
Tradesman and scarce and busy around here. Curse you Tesla with your gigafactory!
I tried to get this project going back in June. The slab is sitting there waiting for framers. If the weather holds, the framers should show up in about 3 weeks. My contractor wants enough calm weather to frame the walls and get the trusses on so the walls don't blow out. It gets breezy around here. The design wind speed here is 125 MPH (i.e. cat 3 hurricane) which affects the size of the footings. We also have 41 psf for snow load.
After my general contractor got time to work on my project, it took about 6 weeks to find someone to do the dirt work. I lucked out that the concrete guy had an opening shortly after the dirt work was done or I might still be looking at a bare pad.
Your bid of ~$6 per square foot sounds like a steal to me but it all depends on the market where you are.
I am in Richmond Va so I would assume that competition would keep the cost down.
