Calibrate the DADU construction-cost screen
All 171,778 included parcels carry the published uncalibrated-cost caution, so the financial result remains a planning sensitivity rather than an empirical Seattle cost finding.
- Scale
- 171,778
- 100% of 171,778
- Geography
- Seattle
- citywide
- Constraint codes
- financial_cost_basis_uncalibrated
Missing capability
A licensed, reviewable Seattle-area DADU cost basis segmented by size, site complexity, soft costs, and observation date.
Current routes
- Versioned planning assumptions and financial sensitivity screen
- Parcel-specific contractor pricing and financing review
Next required artifact
A cost-calibration memo with source provenance, sample coverage, normalization method, uncertainty bands, and a decision on whether to revise gap-dadu-financial@v1.
Success: A reviewer can reproduce the calibrated range and quantify how the revised basis changes the financial stage without hiding uncertainty.
Source artifact: gap-atlas:backyard-cottage:v1
The parcel count measures exposure to an uncalibrated assumption, not financial failure. The current screen is not a bid, quote, appraisal, forecast, or observed project-outcome model. Calibration may change both blocked counts and range-straddle counts and therefore requires a new artifact version. The count tracks the declared denominator, which moved from 186,364 to 171,778 in gap-dadu-v1.3. The exposure remains every included parcel; only the universe changed. Current SMC 23.42.022 uses a 1,000-square-foot ADU cap across the reviewed residential zone families; the 600-square-foot screening unit remains below it.
Published 9/4/2026