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Concrete Slab Cost · New Hampshire

Concrete Slab Cost in New Hampshire (2026)

Concrete Slab in New Hampshire typically runs $9,200–$21,500 for a typical 1,200 sq ft footprint (excavation, gravel base, vapor barrier, rebar, formwork, 4-inch pour, finish). That works out to roughly $7.87–$16.93 per sq ft installed.

Concrete slab foundation pour showing rebar grid and form boards

New Hampshire context that moves a concrete slab foundation cost

Climate: Cold New England climate with heavy snowfall, deep frost lines, and short building season. White Mountains region has extreme weather conditions.

Labor market: Above national average.

Permits & codes: New Hampshire follows the State Building Code based on the IRC. The state has no sales tax, making material purchases tax-free. Local enforcement varies — some towns have minimal oversight while others (especially in southern NH) have comprehensive requirements.

About a concrete slab foundation in New Hampshire

A concrete slab-on-grade is the cheapest residential foundation. For a typical 1,200 sq ft house footprint, budget $6,000 to $15,000 with a national midpoint around $8/sq ft installed. The job takes 5–10 days end-to-end including cure time.

Slabs are the southern foundation default — Florida, Texas, Arizona, and the Gulf Coast use them almost universally because the frost line is shallow and the soil works well. In the Northeast and Midwest, slabs are common for accessory buildings (garages, sheds, additions) but full basements still dominate primary home foundations.

What moves the price

Frost line depth

A slab in Florida sits on 4–6 inches of compacted gravel and a thickened perimeter footing 18 inches deep. The same scope in Minnesota needs footings 48–60 inches deep to get below frost, which doubles the excavation and concrete in the perimeter alone. The biggest single regional cost driver.

Concrete strength and thickness

Residential standard is 3,000–4,000 psi, 4 inches thick. Garage slabs and shop floors go 5 inches at 4,000+ psi. Seismic zones (Pacific states) often require 6 inches at 4,500 psi with additional rebar. Each inch of thickness adds about $1.50/sq ft.

Vapor barrier and insulation

Code now requires a 10-mil polyethylene vapor barrier under the slab. Many cold-climate jurisdictions also require R-10 rigid foam under the perimeter or full slab. Sub-slab foam adds $1.50–$3.50/sq ft.

Finishing tier

Broom finish (rough): included in base price. Smooth troweled finish for exposed floors: $1–$2/sq ft. Stained or polished concrete: $4–$10/sq ft additional. Decorative stamped concrete: $12–$25/sq ft additional.

Site conditions

A flat, accessible lot with truck access within 50 feet of the pour is the base price. Add $1,500–$5,000 for sites with significant slope, rock, or required pumping of concrete over 100+ feet. Coastal flood zones may require elevated slab on piers, which doubles the cost.

Post-tension cabling

Required in expansive-soil areas (north and central Texas, Oklahoma, parts of Colorado and Wyoming) because it lets the slab flex without cracking as soil moves. Adds 20–35% to the slab cost but is non-negotiable in expansive-clay regions.

Concrete Slab cost across New Hampshire metros

Within New Hampshire the spread between metros is usually 25–40% of the state midpoint. Major metros pay more than rural areas because of labor demand, permit complexity, and material delivery overhead.

  • Manchester / Nashua — typical home build $180–$410/sq ft range
  • Concord — typical home build $165–$380/sq ft range
  • Seacoast (Portsmouth) — typical home build $200–$460/sq ft range
  • Lakes Region — typical home build $190–$430/sq ft range

Frequently asked questions

How much does a concrete slab cost in New Hampshire?
A typical 1,200 sq ft slab foundation in New Hampshire runs $9,200–$21,500 — about $7.87–$16.93 per sq ft installed. Includes excavation, gravel base, vapor barrier, rebar, formwork, the pour, and a broom finish.
Slab vs crawlspace vs basement in New Hampshire?
Slab-on-grade is cheapest in warm climates. In New Hampshire's climate (Cold New England climate with heavy snowfall, deep frost lines, and short building season), the frost line and soil type determine whether a slab is even practical. In cold climates where deep footings are required anyway, crawlspace becomes cost-competitive with slab; basements are more expensive but recover floor area.
How long does a slab pour take in New Hampshire?
From excavation to finished slab: 5–10 days for a typical 1,200 sq ft footprint. Excavation 1 day, gravel and prep 1–2 days, formwork and rebar 1–2 days, pour and finish 1 day, cure 3–7 days before framing can start. Cold-weather pours in New Hampshire need extra cure time or admixtures.
Can a slab be poured in New Hampshire's winter?
Yes, with calcium chloride or non-chloride accelerators added to the mix ($25–$60 per yard premium) and insulating blankets covering the slab while it cures. Below 25°F, the cost can climb 15–25% above warm-weather work. New Hampshire's climate (specifically Cold New England climate with heavy snowfall, deep frost lines, and short building season) affects whether winter pours are routine or unusual.
Do I need a permit for a concrete slab in New Hampshire?
Yes for any structural foundation supporting a habitable building. Permits run $200–$700 in most New Hampshire jurisdictions. Slabs for sheds, patios, or driveways often don't require permits but check with your local building department first. Larger residential and any commercial pours always require permits and inspection.

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Related

See the full 50-state a concrete slab foundation cost comparison to see how New Hampshire stacks up nationally.

For broader benchmarks across New Hampshire, see the cost to build a house in New Hampshire.

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