Transparent model and evidence standards

MetalCalc cost methodology

MetalCalc produces an early project-planning range, not a contractor quote, appraisal, bid, engineering opinion or promise of market price. The calculator applies one documented model to the dimensions, scope and options selected by the user. The same assumptions drive the homepage calculator and every preconfigured size guide.

What the three ranges mean

Low, Typical and High are three independent scenarios. Each scenario uses the matching price tier for the building package, concrete, erection, optional systems and fixed allowances. Planning contingencies of 5%, 10% and 15% are added respectively. They are not statistical confidence intervals. The range stays deliberately broad because supplier scope, code requirements, site conditions and labor availability differ.

How pricing evidence is selected

MetalCalc uses publicly reviewable supplier prices, government fee schedules, government labor data, contractor-published ranges and specialist cost guides. A source is useful only when its scope can be identified. Material-only prices are not averaged with installed prices; installed tubular packages are not averaged with red-iron kits; and a concrete surface price is not presented as a complete structural foundation.

Government and supplier-published records receive the most weight when their date, unit and inclusions are clear. Contractor ranges help define variation. Editorial cost guides are used as cross-checks rather than as the sole basis for Typical. Anonymous claims and prices without a usable scope do not set the published ranges.

Representative public evidence

• U.S. Bureau of Labor Statistics — state occupational employment and wage data: Used only as a broad labor-market proxy; wages are not treated as installed contractor prices.
• City of Columbus — commercial building and trade permit fee schedule: A government-fee reference used to test the scale of building and trade permit allowances.
• City of Commerce, Georgia — public concrete services price sheet: A public-procurement reference for four-inch and reinforced six-inch concrete unit prices; it is not treated as a universal building-slab quote.
• Mason Steel Buildings — published 30×40 red-iron starting price: A supplier-published package reference normalized as kit pricing rather than a completed-project total.
• Simpson Steel — published 40×60×16 building kit: A larger-kit reference with shipping separated from the advertised package price.
• Alan's Factory Outlet — installed tubular metal buildings: An example of tubular pricing that advertises delivery and installation together, which must not receive a second erection charge.

This list shows representative inputs, not every record in the research dataset and not an endorsement of a vendor. Public prices can change after review. A written local proposal with a defined scope should take priority over a planning allowance.

Geometry and structural package

Floor area equals width multiplied by length. Building perimeter equals twice the width plus twice the length. Roof and wall areas use a conceptual symmetrical 4:12 roof. Structure rates are multiplied by continuous floor-area and eave-height factors. Linear interpolation prevents a small change in size from crossing a pricing boundary and producing an unrealistic drop in the structural total.

Frame and scope treatment

Tubular installed-shell research commonly packages erection with the building price, so MetalCalc does not add a second erection charge. Red-iron projects show the kit and erection separately. Kit Only, Erected Shell and Turnkey Planning remain separate scopes. When frame type is unknown, the calculator presents complete tubular and red-iron alternatives instead of combining a low value from one system with a high value from another.

Foundation planning

A floor slab is not treated as a complete structural foundation. Four-inch and six-inch selections include the slab, a conceptual perimeter-based structural-footing allowance and foundation engineering. Heavy Duty includes a wider slab and footing allowance. None of these choices determine concrete strength, reinforcement, footing dimensions, piers, grade beams, anchors, frost protection or soil suitability.

Location and optional systems

The state selection maps to a broad labor region. That proxy adjusts only itemized red-iron erection and site-preparation labor. It does not automatically change steel, concrete, freight, permits or optional systems. Electrical combines a fixed service allowance with a floor-area allowance. HVAC uses conditioned area and adds a separate equipment allowance for the commercial selection.

Worked calculation example

For a 30×40 building, floor area is 1,200 square feet and perimeter is 140 linear feet. A red-iron erected-shell scenario first applies the selected kit rate to 1,200 square feet, then applies the continuous size and height factors. Erection is calculated separately because it is not bundled with the red-iron kit. If delivery or manufacturer plans are unconfirmed, their allowances remain visible. The scenario subtotal receives its matching contingency only after every included category is assembled.

If the same project changes to Turnkey Planning with a four-inch slab, the model adds site preparation, 1,200 square feet of slab allowance, 140 linear feet of conceptual footing allowance plus mobilization, foundation engineering and a building-permit allowance. This explains why the completed-project range cannot be inferred from an advertised kit price alone.

Supported range and exclusions

The numeric model supports 600–10,000 square feet, 8–24 foot eave heights and the contiguous United States. Alaska, Hawaii, larger industrial work and custom aircraft-hangar doors require project-specific pricing. Sales tax, land, financing, demolition, utility extensions, interior finishes, fire sprinklers and unusual remediation are excluded unless a result explicitly says otherwise.

Brand-level review and corrections

The pricing configuration is maintained under the MetalCalc brand. Each scheduled review checks source availability, dates, scope consistency, outliers and regression results before a new version is published. A price change requires a new version, an updated review date and a repeatable calculator test. Dates are not changed merely to make content appear newer.

Reports of a broken source, calculation error or unclear inclusion can be sent through the contact page. A correction is evaluated against the same scope rules before it changes the calculator. Review the full estimate disclaimer before relying on any result for a purchasing or construction decision.