Foundation Cost Estimator

Price the part of the building you'll never see again. Pick a foundation type and structure size — get concrete volume, granular base tonnage, and an itemized 2026 cost estimate with editable prices. Not sure which type? The slab vs frost wall guide resolves that decision first.

Structure & Foundation

Foundation Type

The standard for detached garages on drained sites.

Length (ft)

Width (ft)

Slab thickness

Granular base depth

Adjust unit prices (CAD, editable)

Concrete, delivered ($/m³)

Forming, placing & finishing ($/sq ft)

Contractor labour for slab work. Set lower if DIY.

Mesh / rebar allowance ($/sq ft)

Granular, delivered ($/tonne)

Frost wall, formed ($/lin ft per ft of depth)

Includes excavation, forming, concrete, backfill.

Per pier, installed ($)

Wood floor system ($/sq ft)

PT skids, joists, sheathing — materials + modest labour.

Estimated foundation cost

—

Quantities & Cost Breakdown

Item	Quantity	Cost

Refine the rest of the build: price the granular base order in the Fill & Gravel Calculator, the walls in the Wall Framing Calculator, the roof in the Roof Cost Estimator — or get the whole-building ballpark in the Garage Cost Calculator.

Disclaimer: This is a planning-level quantity and cost estimate using typical assumptions (thickened-edge floating slab, standard forming). It is not a structural design — slab thickness, reinforcement, frost depth, and pier sizing are set by your soil, your provincial code, and your permit drawings. Piers exclude beams and floor framing. Confirm with your building department and local contractors.

How this estimate works

Slab: concrete volume = area × thickness (+10% waste), granular base = area × depth × 1.8 t/m³ with compaction allowance, plus mesh/rebar and forming/finishing labour at your editable rates. Frost wall adds perimeter × depth × the formed-wall rate to a standard slab. Piers: perimeter ÷ spacing, at your per-pier installed price. Wood floating floor prices the PT skid-and-joist system per square foot — common for sheds under ~160 sq ft where code permits (see the permits guide). The result is shown ±15%.

What drives the number

Frost depth decides the whole problem. A foundation in Canada exists mainly to keep the building above ground that freezes and heaves. Local frost depth — which varies enormously across the country — sets how deep a frost wall must go, and depth drives excavation volume, formwork area, and concrete quantity all at once. It's also why the same garage costs meaningfully different amounts in different provinces before a single price changes.

Perimeter drives frost wall cost; area drives slab cost. These scale differently, and it matters when comparing designs. A long narrow building has more perimeter per square foot than a square one, so it costs disproportionately more to put on a frost wall and about the same to put on a slab. If you're on the edge of affording a frost wall, a squarer footprint is a free saving.

Granular base is a bigger line than people expect, especially on soft ground where you're excavating out unsuitable material and replacing it. Compacted granular under a slab does two jobs — it spreads load and it breaks capillary rise so water can't wick up into the concrete. Under-building it is the usual cause of a slab that cracks or a floor that's permanently damp. Price the material with the Fill & Gravel Calculator.

Concrete is priced by the cubic metre and delivered by the truck, which means partial loads, short-load surcharges, and pump rental where a truck can't reach the forms. Access is a genuine cost variable: a pour a truck can chute directly into is cheaper than the identical pour that needs a pump or wheelbarrows.

The choice may not be yours. Whether a slab-on-grade is acceptable, or whether you need footings below frost, is set by your municipality, the structure's size and use, and your soil — not your budget. Confirm before you price. Our slab vs. frost wall guide walks through when each is permitted and why.

Wood floating floors are a narrow exception, not a general option. A pressure-treated skid-and-joist system is common and sensible for small sheds where code permits it, and entirely unsuitable for anything you'll drive a vehicle into. Check the size threshold locally before assuming it applies.

What this estimate does not include

Site access and excavation beyond the foundation footprint — stripping topsoil, removing trees or stumps, cutting a path for equipment, and hauling spoil away.
Rock. Bedrock or large boulders turn routine excavation into breaking or hammering, at a completely different rate. Nothing here can predict it.
Dewatering on high-water-table sites, and the drainage that may be required around a frost wall — weeping tile, drainage stone, damp-proofing.
Under-slab services: plumbing rough-ins, conduit, radiant tubing, and any sleeving that has to be in place before the pour. Adding these after concrete is expensive and ugly.
Rigid insulation under or around the slab, which is required for heated slabs and is a good idea for many others.
Engineered design. Prescriptive footing tables cover standard cases; unusual soils, poor bearing, or non-standard structural conditions need a professional engineer.
Permits, surveys, and inspections. Most municipalities inspect footings and formwork before the pour — schedule it, because pouring ahead of inspection can mean exposing the work again.
Curing time. Not a cost line, but a schedule one, and cold-weather pours add heating, blankets, or admixtures.

For where the foundation sits in a whole-building budget, see the Garage Cost Calculator.