Concrete Slab Foundation Cost 2026: 1,200 Sq Ft $8,150 to $19,220
A 1,200 sq ft (30×40) concrete slab foundation costs $8,150 to $19,220 for the slab, typically $11,970, or $6.80 to $16.01 a sq ft, at prices read in October 2026. That covers a monolithic slab with rebar, vapor retarder, stone base and thickened edges. Excavation, deeper footings, under-slab plumbing and permits are extra, and frost depth decides which foundation you can use.
Slab Foundation Cost by Footprint
| Footprint | Sq Ft | Typical | Low to high | Per sq ft | For |
|---|---|---|---|---|---|
| 20×40 | 800 | $8,350 | $5,650 to $13,330 | $7.06–$16.67 | Cottage, small addition |
| 30×40 | 1,200 | $11,970 | $8,150 to $19,220 | $6.80–$16.01 | Small single-storey home |
| 30×50 | 1,500 | $14,760 | $10,060 to $23,220 | $6.70–$15.48 | Mid-size home |
| 40×50 | 2,000 | $19,310 | $13,170 to $30,390 | $6.58–$15.20 | Larger single-storey footprint |
| 50×50 | 2,500 | $23,810 | $16,280 to $36,980 | $6.51–$14.79 | Large footprint |
| 50×60 | 3,000 | $28,360 | $19,390 to $44,150 | $6.46–$14.72 | Very large footprint |
Monolithic slab: 4-inch 3,000 PSI floor, #4 rebar at 18 inches, 6-mil poly, 4-inch stone base, edge thickened 12 in wide x 8 in below the floor (our assumption), national prices. For a 1,000 sq ft slab see the 1,000 sq ft slab page.
Slab, T-Shaped, Crawl Space or Basement
| Foundation | Price | How it is built | Used where |
|---|---|---|---|
| Monolithic slab (thickened edge) | $8,150 to $19,220 for 30×40 | Floor and edge poured together; the edge is thickened to act as the footing | Where frost is shallow, or with a frost-protected shallow foundation (IRC R403.3) |
| T-shaped (footing, stem wall, slab) | Quote: no primary price found | Footing poured below the frost line, a short wall on top, then the floor slab | Where frost runs deep: the footing bears below the local frost line (IRC R403.1.4.1) |
| Crawl space | Quote: no primary price found | Perimeter footings and walls with a framed floor above a ventilated or conditioned space | Sloping lots, or where access to plumbing under the floor matters |
| Basement | Quote: no primary price found | Deep excavation, full-height walls, waterproofing and a basement floor slab | Deep frost, or where the extra space is wanted |
We price only what our inputs cover. Footings, stem walls, crawl spaces and basements depend on frost depth, soil and the design, and we found no published price list or public bid for them, so ask your builder to price the options on the same footprint.
Concrete Footings
A footing is the wider strip of concrete the walls or the slab edge bear on. In a monolithic slab the thickened edge is the footing, and its cost is in the table above. In a T-shaped foundation the footing is poured first, below the frost line your building department sets, with a stem wall on top; its size comes from the plans. Ask for footings as their own line on the quote, with the width, depth and steel stated, so you can check the concrete volume against the per-yard prices on our concrete cost per yard page.
Frost Depth Sets the Foundation Type
Frost depth is set locally, not nationally: each jurisdiction records its design frost depth in its climate table (IRC Table R301.2(1)). Under IRC R403.1.4.1 a foundation must be protected from frost by extending below that frost line, by being built as a frost-protected shallow foundation to R403.3 (written mainly for heated buildings), by design to ASCE 32, or by bearing on solid rock. A plain monolithic slab whose thickened edge stops above the frost line meets none of these, and is exposed to frost heave.
Ask your building department for the local frost depth before pricing, and have a structural engineer or designer specify new-construction foundations. This is not a DIY decision.
Sources: International Residential Code (ICC) sections R109.1.1, R301.2, R401.4, R403.1.4.1, R403.3 and R506.1, checked on 13 October 2026 against state- and county-published adopted text (Minnesota Rules ch. 1309, the California Residential Code, Los Angeles County Residential Code Manual R401.4). Local amendments can differ. The R506.1 slab minimum was checked by hand on 13 October 2026 against the adopted code text, which writes it as "a minimum 3½ inches (89 mm) thick" (Minnesota Residential Code 2020, adopting the 2018 IRC, R506.1, as published by UpCodes; the 2025 California Residential Code R506.1 gives the same 3½-inch figure).
How We Price a Slab
Every installed price on this site comes from one model: published ready-mix and materials prices, plus crew hours priced at Bureau of Labor Statistics wages, plus overhead and margin. The low figure uses the lowest published input and our lowest assumption at every step; the high figure uses the highest. The crew hours, overage and margin are our own estimates, not published figures, and are listed below so you can check them against your quote. Worked example: a 30 x 40 ft (1,200 sq ft) foundation slab (4-inch floor (above the IRC R506.1 minimum of 3.5 inches), 3,000 PSI, #4 rebar, 6-mil vapor retarder, 4-inch stone base, thickened edge 12 in wide x 8 in below the slab (assumed; your plans set it)).
| Line | Low | Typical | High | Basis |
|---|---|---|---|---|
| Ready-mix concrete | $2,437 | $2,789 | $3,316 | 18.27 cu yd plus 5 to 10% overage, at published per-yard prices |
| Delivery and small-load charges | $0 | $70 | $1,257 | Per-truck charges from the same price lists (10 yd per truck) |
| Crushed-stone base | $782 | $975 | $1,329 | 4 in compacted crusher run |
| Reinforcement | $890 | $890 | $890 | #4 bar at 18 in each way, laps and chairs |
| Form lumber | $53 | $80 | $106 | Perimeter boards, shared across reuses |
| Vapor retarder | $86 | $86 | $86 | 6-mil polyethylene |
| Crew labour | $2,546 | $4,320 | $6,741 | Crew hours x BLS wages x employer costs |
| Overhead and margin | $1,359 | $2,763 | $5,490 | 20% to 40% on direct cost |
| Installed total | $8,150 | $11,970 | $19,220 | Rounded to the nearest $10 |
Not included: excavation and soil haul-off, removing an old slab, permits, pumping, decorative finishes and sealing. Totals are national; the calculators’ state option swaps in that state’s BLS wages and leaves concrete and materials at the published lists.
Published inputs (read 13 October 2026)
- Ready-mix, per cubic yard: 3,000 PSI $127.05 to $165.00, 4,000 PSI $132.00 to $175.00, from Supreme Concrete (Los Angeles, CA), Minimix Concrete (Pequannock, NJ), Gehring Construction & Ready-Mix (Columbus, NE, list dated 2026-01-01), Scenic City Ready Mix (Tennessee, list dated 2024-08-03).
- Small orders and trucks: short-load charge $50 under 4 yd (Gehring) or $100 at 5 yd or less, plus $100 more at 2 yd or less (Scenic City); per truck, no charge within 20 miles (Gehring), a $35 surcharge (Scenic City), or $363.88 Zone A delivery plus a $55 environmental fee (Supreme).
- Crushed-stone base: $44.00 to $74.75 per cubic yard from D & L Supply (Central New York, $44.00/yd), JMJ Companies (Lynchburg, VA, $39.50/ton), Golden Landscaping Supply (Cumming, GA, $50.00/ton), Yard Works Landscape Supply (Fort Mill, SC, $74.75/yd); per-ton prices converted at 2,450 lb per yard.
- Steel, forms, poly: #4 rebar 20 ft $8.99, 6x6 10-gauge mesh 4x8 panel $6.99, 2x6x12 $14.32, 2x4x16 $12.13, 6-mil poly 8 ft 4 in x 100 ft $59.99, rebar chair $0.33 (Menards online prices; Home Depot and Lowe’s pages could not be read that day). That works out to $0.24 per sq ft for mesh and $0.74 per sq ft for a rebar grid, materials only.
- Wages: BLS OEWS 47-2051 cement masons (May 2025) 25th percentile $22.60, median $27.41, 75th $32.15 an hour; 47-2061 construction laborers $18.57, $22.66, $28.72. Employer costs from BLS ECEC June 2026, construction industry ($51.96 total compensation per $36.13 of wages, x1.44): a crew hour costs $29.60 to $43.77.
Our assumptions (estimates, not published figures)
- Crew: half cement masons, half laborers.
- Setup per job: 8 to 16 crew hours (layout, stripping, cleanup).
- Per 100 sq ft: 4-inch 4 to 7 crew hours, 6-inch 5 to 8.5, 8-inch 6 to 10; add 0.5 to 1 for mesh or 1.5 to 2.5 for rebar.
- Concrete overage 5% to 10%; base stone ordered at 1.2x its compacted volume; form boards charged at half to all of their price.
- Overhead and margin 20% to 40% of direct cost.
- 6-inch and thicker slabs use 4,000 PSI mix; thinner slabs 3,000 PSI.
Sources: BLS OEWS 47-2051 cement masons (May 2025), BLS OEWS 47-2061 construction laborers (May 2025), BLS ECEC, construction (June 2026), ready-mix price lists from Supreme Concrete, Minimix Concrete, Gehring Construction & Ready-Mix, Scenic City Ready Mix, crusher-run prices from D & L Supply, JMJ Companies, Golden Landscaping Supply, Yard Works Landscape Supply, Menards mesh, rebar, lumber and poly prices. All read 13 October 2026. Crew hours, overage, overhead and margin are our estimates and are listed in the method above.