The national range
National cost guides put a concrete slab at about $4 to $12 per square foot installed, with most homeowner pads landing toward the middle. Basic thin pads with easy access sit at the bottom; reinforced, thickened or finished slabs, and small jobs, sit at the top.
Common sizes
| Slab | Area | At $4–$12 per sq ft |
|---|---|---|
| 8 × 8 hot tub pad | 64 sq ft | $256–$768, often subject to a job minimum |
| 10 × 12 shed pad | 120 sq ft | $480–$1,440 |
| 12 × 24 RV pad | 288 sq ft | $1,152–$3,456 |
| 24 × 24 garage slab | 576 sq ft | $2,304–$6,912 |
| 30 × 30 shop slab | 900 sq ft | $3,600–$10,800 |
| 40 × 60 pole barn floor | 2,400 sq ft | $9,600–$28,800 |
A 30 by 30 slab at 4 inches thick holds about 11 cubic yards of concrete before waste (900 sq ft × 0.333 ft ÷ 27). Thicker slabs scale up from there, which is one reason a shop floor specified at 5 or 6 inches costs more per square foot.
What moves a slab quote
- Thickness and edges. Building slabs often need thickened edges or footings to Boise's 24-inch frost depth.
- Base. Gravel depth and compaction; caliche or wet ground changes the dig.
- Reinforcement. Rebar grid or mesh, and dowels into an existing slab.
- Finish. Broom, smooth trowel for a shop floor, or decorative.
- Access. Long carries on acreage may need a pump.
- Extras. Floor drains, conduit for power, vapor barrier, sealing.
- Minimum charges. Small pads rarely benefit from the low end of the range.
For what the slab needs to be, see concrete slabs; for footings and pole barns, concrete foundations. For other concrete work, see concrete cost in Boise.
Back to the main guide: Boise concrete contractors.