12' x 14' x 6" concrete slab approx cost

I recently had some concrete work done, and for a 4” slab every contractor I spoke with came in at $8.50/sqft. So I’d imagine higher than that for 6”.

18’x25’ slab cost me $3,800.

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Why 6”?

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The slab is for a swim spa - basically a big hot tub with water jets creating a current to swim against. Figured I would need at least a 6" slab.

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Figured I would need at least a 6" slab.

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Your driveway is only 4” thick and has a lot of heavy shite on it.

Any steel?

$6-8/sqft is pretty normal for a 4” slab. 6” is just the extra cost for concrete. Probably around $2-3/sqft extra.

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No steel

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You at least need some mesh to hold it together. Concrete has no tensile strength so it will crack up and settle unevenly.

Just got quotes around $2500 for 12x12. I think I can find cheaper

Typically mesh is held up in a slab. I feel like you will want some mesh lower in your concrete especially around the perimeter of the spa. This will keep the edges of your slab from flexing upward as your spa sinks the middle. This will depend on the distance from the edge of the spa to the edge of the concrete and what’s under your concrete.

On something so thin as 4” any mesh should be placed at mid depth

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I thought concrete, dirt etc was sold by the cubic yard instead of square foot?

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The concrete itself, yes. The steel and labor are not. Since most concrete slabs are a set thickness, it’s easy to convert that cuyd concrete cost to sqft, then add steel and labor on top of that. It gives a much easier number for bids and people to calculate.