Transparent assumptions are more useful than a mysterious score.

1. Scope before price

Each checker begins with cost drivers a homeowner can reasonably identify: equipment type and capacity, project size, access constraints, included extras, urgency, and ZIP-code region. A result is only as relevant as those selections.

2. Component ranges

Equipment, labor, materials, permits, disposal, access, and optional work are represented as separate low-to-high allowances. Components are added—not hidden inside a proprietary score—so users can see why the range moved.

3. ZIP, trade wage, and regional adjustment

A recognized ZIP is mapped to a state and to a BEA regional-price area. Marked labor rows use a transparent weighted factor: 75% of the selected state's BLS occupational-wage ratio for the relevant trade and 25% of the BEA all-items Regional Price Parity. HVAC work uses the HVAC-mechanic occupation, plumbing work uses plumbers, electrical conversion work uses electricians, and tree work uses tree trimmers and pruners. Equipment and ordinary material allowances are not multiplied by this labor factor.

The weighting is a deterministic planning convention, not a statistical claim about a specific contractor's payroll or margin. BLS state wages improve trade specificity; BEA RPP retains a limited allowance for broader regional service overhead. If the live validated snapshot is unavailable, the page explicitly reports an embedded fallback and uses the older BEA regional proxy rather than silently inventing current local data.

4. Quote comparison

A quote inside the modeled range is marked “within estimated range.” Because estimates are rounded and real scopes rarely match perfectly, a quote up to 5% beyond either modeled boundary is labeled “near estimated range” instead of being treated as meaningfully outside it. A quote beyond that tolerance is still not automatically unfair or fraudulent. The report explains the difference and suggests scope items that may justify it. Unusually low offers trigger an exclusion check rather than an accusation.

5. Official and public data sources

• BLS Occupational Employment and Wage Statistics: national and state median hourly wages for plumbers, electricians, HVAC mechanics, and grounds-maintenance workers; annual release.
• BEA Regional Price Parities: metro and state all-items price levels.
• EIA residential electricity prices and residential natural-gas prices: state averages used only for clearly labeled operating-cost scenarios.
• ENERGY STAR certified water-heater data: product count, UEF, and annual-use summaries for current certified products.
• Curated US ZIP dataset: ZIP-to-state reference under CC BY 4.0.
• NBER county-to-CBSA crosswalk: based on Census delineations.

Every live report displays its model version, generation date, source periods, and whether the validated snapshot loaded successfully. ZIP data is a lookup convenience, not a legal boundary.

6. Service reference framework

Base component allowances are broad national planning guardrails cross-checked against multiple current consumer-cost references and public technical guidance. They are not copied price quotes, private contractor bills, or a real-time bid feed. The official automated snapshot changes regional labor, current state energy rates, and certified-product summaries; it does not scrape publishers or automatically overwrite base price bands from an unverified page.

• HVAC: Angi HVAC cost guide, HomeAdvisor heating and cooling guide, and ENERGY STAR quality-installation guidance.
• Tree removal: HomeGuide tree-removal cost guide, HomeAdvisor tree-removal guide, and Angi tree-removal guide.
• Water heaters: The Home Depot installation guide, Angi water-heater guide, and the U.S. Department of Energy's tankless sizing guide.
• Air ducts: the U.S. EPA consumer guide and Angi air-duct guide. Mold remediation, moisture correction, pest extermination, entry-point sealing, and damaged-duct repair are explicitly outside the cleaning allowance.

These sources help set scope and national guardrails. They cannot determine a binding local bid without an address, inspection, current equipment availability, and contractor-specific scope.

7. Automatic update and validation policy

The public data pipeline runs every Tuesday at 09:17 UTC. It downloads the official/public inputs, checks source availability, schema, units, state, metro, and ZIP coverage, plausible numeric bounds, and regression invariants, then publishes a versioned JSON snapshot only when every validation passes. A failed refresh leaves the last validated snapshot in place. No generative AI participates in extraction, pricing, scoring, or publication, and no manual approval is required for a valid run.

The source and validation code is publicly inspectable in the QuoteVerity data repository. EIA rates are checked weekly but typically change monthly; ENERGY STAR, ZIP, and BEA archives are checked weekly; BLS's release page is checked weekly and full wage series are downloaded only when a new annual release appears. A newer website date never substitutes for the period reported by the source.

8. Permits, codes, and licensing

Building, mechanical, plumbing, electrical, fuel-gas, energy, tree, right-of-way, and contractor rules may be adopted or enforced at state, county, city, district, utility, parcel, or address level. One ZIP can cross multiple jurisdictions. The result therefore provides a project-specific verification checklist but never claims that a permit is or is not legally required. Users should confirm the street address and written scope with the authority having jurisdiction before work begins.

9. Optional local document reader

The quote importer uses a locally executed PDF text reader and PaddleOCR PP-OCRv6 tiny models served from QuoteVerity. It is not generative AI and does not send a document to cloud OCR. OCR output is never treated as ground truth: the interface requires the user to review totals, amounts, model numbers, scope, exclusions, and warranty text before the calculator accepts the confirmed total.

Automatic pattern redaction removes common phone, email, street-address, account, signature, and payment lines as an additional safeguard. It cannot identify every private detail. Users are instructed to mask the original first. The importer, calculator, and PDF generator use browser memory only; no quote history, raw OCR, upload, or report is persisted by QuoteVerity.

10. Known limitations

• No property inspection, address-level jurisdiction lookup, physical measurement, or independent verification of a contractor document.
• OCR may omit or misread text, decimal points, totals, exclusions, models, dates, or handwriting; user confirmation is mandatory.
• No verification of concealed damage, structural conditions, final equipment sizing, code requirements, tax, inventory, insurance, license status, or workmanship.
• State occupational wages and metro price levels are regional aggregates, not a city-specific contractor quote.
• Water-heater operating costs are energy-only scenarios using current state averages and explicit product/use assumptions—not utility-bill forecasts.
• Rebates are never deducted automatically because eligibility depends on address, income, model, installation date, program funding, and tax circumstances.
• Unusual access, emergency supply conditions, financing, premium brands, negotiated discounts, and scope omissions can move a real quote outside the range.

Review date

National component guardrails and consumer-facing language were reviewed in August 2026. The report itself shows the current automated data-snapshot date. Results should be saved only as a point-in-time planning reference.