I'm thinking about building 900sq ft basement and will live in it for a while before finishing the top of house later down the road. What would the cost be for ten ft walls and slab verses the conventional concrete walls.
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Looking for construction cost online is not very practical due to the fact that cost of concrete work or cost of construction in general vary widely from state to state as well as city to city.
Instead of providing an estimate, I can provide ways you can get the estimate in your area. The first step is figure the cost of concrete. This can be determined by calculating the length of your footing and foundation walls.
The 900 square feet mentioned does not tell me how long the footing and foundation walls. Assume the basement is 20x45feet which will yield the 900 square feet. Your footing and foundation walls length will be 130 feet.
Most basement footings are 10x20 inches (10” deep x 20” wide). The formula to figure how much concrete you need for footing is LxWxH.
Applying the above info to the formula yields 10/12 x 20/12 x 130 = 181 cubic feet divide by 27 yields 6.7 cubic yards. Since 10 and 20 were in inches, the divide by 12 converts to feet. To convert cubic feet to cubic yards, divide by 27 because concrete are sold in the US in yardage.
To estimate the concrete for the foundation walls use the same formula above. Since most foundation walls are 8 inches thick, we have 8/12x10x130 = 867.7 cubic feet divide by 27 =
32 cubic yards.
To figure the concrete for your slab, you use the same formula above, 4/12x900sf = 300 cubic feet/27 = 11.1 cubic yards.
As far as concrete cost you will need 6.7+32+11.1 = 49.8 cubic yards of concrete. If concrete cost $100 per yard in your area, your concrete alone will cost $5,000+ tax.
The other things needed for concrete are anchor bolts and rebars for reinforcements. Rebars normally spaced at 24 inches on center horizontally and vertically for walls and footings.
You will need about 2000 feet of rebar at about 40 cents a foot will add another $800 to cost of materials.
Other things that need to consider is how far your property from concrete supplier and if the concrete can be delivered to your site without the need of concrete pump. All of these will affect the cost.
Concrete labor also varies from state to state, suppose it cost $20 per foot for footing and foundation walls, your labor cost will be $2,600.
Rather than looking online for cost that my not apply in your particular area, you can figure the material quantity and call concrete suppliers at your area and get a more realistic material cost.
You can follow the same way by calling concrete contractor and ask for a labor cost to go with the material cost that you calculated.
One more thing, mentioned above is about concrete only and does not include excavations and roof. To make your basement livable, it needs a roof. Whether you are going to use the floor for above as roof for now it still needs to be considered in the plan.