Methodology

Model versioning

The crawl-space engine is version 1.0.0 (effective 2026-07-01, reviewed 2026-07-15). Content updatedAt dates are independent of model version. Wording edits do not bump the model. From 1.1.0 onward, prior model implementations or complete calculation snapshots will be retained so old saved results are never silently recomputed with new constants.

How rates are collected and validated

Every meaningful RateDefinition stores source IDs, a reviewedAt date, unit, low/typical/high cents, and notes describing cost-basis vs installed retail. National rates are calibrated across government wage relativity, industry cost data, manufacturer guidance, and publisher research summaries. No single contractor webpage sets a national rate.

Author Alan Lee maintains the registry; technical review checks that published claims still match the live model before money pages ship.

Independent scenario ranges

Low, typical, and high totals are each calculated from scenario-specific rate values. We do not apply a final percentage markup to a single mid estimate to create the range.

Overhead and installed retail

Project subtotal includes materials, labor, equipment, disposal, permits, and mobilization. Contractor overhead and margin apply to cost-basis subtotals. Rates marked installed retail (for example dehumidifier packages) do not receive another full markup.

Regionalization

Labor indices adjust labor only. Material indices adjust materials only. Climate and moisture context appear as explanations and never mutate dollars.

Unsupported projects

Commercial/multifamily, sizes beyond limits, inaccessible crawls, severe active flooding, major structural damage, unsupported states, and conditioned-air systems return no estimate. We do not emit an ultra-wide range as a substitute.

Sensitivity and confidence

Sensitivity drivers are counterfactual recalculations (typical with driver minus typical without). Only material impacts (≥ $100) are shown. Confidence (limited / moderate / strong) reflects input completeness and applicability—not source quality and never a percent accuracy claim.

Non-diagnostic statement

This model does not diagnose the correct moisture solution. An estimate prices the work you selected. It does not determine whether that work is the correct solution for the moisture source.

Rounding

Internal math uses integer cents. Display rounds line items to the nearest dollar, totals to the nearest $50, and $/sq ft to two decimals to avoid false precision.