Very very generally speaking - a foundation for a two story building would be at least 24" wide and 18" deep. It would include rebar... in some areas you'd need 24" depth...
A cubic yard of concrete would be 36"x36"x36".. .or 64,656 cubic inches.
So 24"x18"x12" of footing would take 5181 cubic inches of concrete per running foot. {about 12.5 feet per cubic yard}.
Your drawing shows 128 running foot of footer required or 663,552 cubic inches -divided by 64,656 equals 10.35 cubic yards of cement.
Around here 2500 psi concrete can run $95.00 per cubic yard.. plus you will have some waste.. so figure 11 cubic yards = $1045.00 for concrete.
I'd guess you would have a couple hundred dollars in rebar...
Labor to layout and dig the footers... three guys that knew what they were doing and had years of experience.... would be ready to pour concrete in a day. 3x8= 24 hours of labor. Pay them $25.00 per hour... $600.00
Add the cost of the forming materials... another couple hundred at most {reusable in many cases}...
At dead cost that gives you about $2000.00.... for the footer. So yes a reasonable price for a high quality concrete sub-contractor would be around $4000.00 The contractor will have all kinds of overhead to take out of that.... and by the time he's done, he'll be lucky to clear a 10 to 15% profit.
The floor
30x20 = 600 sq ft.
14x24 = 336 sq ft
= = = = = = 936 sq. ft...
If the same contractor pours the floor - figure $3.50 to $4.50 per sq ft. or another $3K to $4K.
If you add insulation or have problems with the ground for any reason it would go up accordingly.
OK - everyone feel free to correct anything...... my estimates are based on an area in which business is slow today and cash is king.
FWIW,
Carl B.
