What BarnCost estimates
The calculator turns a structured project — size, use, scope, slab, insulation, electrical, and openings — into a low / expected / high range and a component breakdown. Pages for sizes and building types read the same structured objects. Articles do not keep their own pricing tables.
What the estimate includes
Included items depend on scope and on whether a documented cost component exists for the selected feature. If a feature is selected but has no sourced unit cost, BarnCost states that the input is missing instead of filling the gap with a guess.
What it does not include
Land, unusual excavation, long utility extensions, living quarters, full HVAC, sales tax, and local permit variance beyond a documented allowance are excluded unless they are later added as sourced components.
Kit, installed shell, and finished building
- DIY kit: materials or package pricing.
- Installed shell: the structural building erected.
- Turnkey / finished: a more complete project with selected features.
These are different products. BarnCost will not blend kit pricing and completed-project pricing into one average.
Low, expected, and high
Every money range must satisfy low ≤ expected ≤ high. Expected is a central value from the sourced component, not a promise that a bid will land on that number. Ranges exist because construction pricing is variable.
Sources
Production cost components must point at CostSource records. A number without a source id is invalid data and fails catalog validation. Source types include manufacturers, builders, contractors, government publications, trade publications, suppliers, cost databases, real projects, and expert input.
Regional adjustments
Geography resolves metro → state → national. A factor is applied only when it includes a documented material or labor multiplier. A national placeholder without multipliers does not silently pretend that every market prices the same.
Estimate confidence
Confidence is low, medium, or high, with reasons such as national fallback, limited regional data, or missing feature components. BarnCost does not automatically label estimates as high-confidence.
Data versions and dates
Each catalog has a pricing data version and optional effective and last-updated dates. Updating inputs should not silently erase the version that produced an estimate.
Real-project data later
Completed projects will eventually sit on the same CalculatorConfig shape so they can be compared with estimates. No real-build records are published until they exist.
Why ranges instead of exact prices
Construction pricing varies by location, builder, site conditions, material markets and project specifications. BarnCost provides estimated ranges rather than claiming to provide an exact contractor quote.