{ "schema_version": "0.5.0", "analysis_version": "spike-0.1", "generated_at": "2026-10-14T19:08:52+00:00", "uptake": { "default": 0.02, "min": 0.005, "max": 0.1, "step": 0.005, "horizon_years": 10, "basis": "Share of buildable lots that add an ADU within 10 years. Observed US rates after reform are roughly 2-3% over a decade (Seattle 2019-2024; lowest-value California neighborhoods), with rare outliers near 8%. This is an assumption, not a forecast.", "sources": [ { "name": "Seattle OPCD ADU Annual Report 2024", "url": "https://seattle.gov/documents/Departments/OPCD/OngoingInitiatives/EncouragingBackyardCottages/OPCD-ADUAnnualReport2024.pdf", "retrieved_at": "2026-10-13", "vintage": "2024", "caveat": null }, { "name": "Terner Center, Reaching California's ADU Potential (2020)", "url": "https://ternercenter.berkeley.edu/wp-content/uploads/pdfs/Reaching_Californias_ADU_Potential_2020.pdf", "retrieved_at": "2026-10-13", "vintage": "2020", "caveat": null }, { "name": "NYU Furman Center, Evaluating California's ADU Reforms", "url": "https://furmancenter.org/files/Evaluating_California%E2%80%99s_Accessory_Dwelling_Unit_Reforms_508.pdf", "retrieved_at": "2026-10-13", "vintage": "2018-2021 permits", "caveat": null } ] }, "formulas": { "modeled_adus": "round(buildable × uptake_rate); at most one ADU per lot", "housing_growth_pct": "modeled_adus / baseline.housing_units × 100; unknown when baseline is null" }, "cities": [ { "id": "cleveland_heights", "name": "Cleveland Heights", "coverage": "partial", "bbox": [ -81.603198, 41.48277, -81.529655, 41.545292 ], "summary_path": "cities/cleveland_heights/summary.json", "lots_index_path": "cities/cleveland_heights/lots/index.json", "hexes_path": "cities/cleveland_heights/hexes.geojson", "boundary_path": "cities/cleveland_heights/boundary.geojson" }, { "id": "lakewood", "name": "Lakewood", "coverage": "partial", "bbox": [ -81.843982, 41.463247, -81.768572, 41.500048 ], "summary_path": "cities/lakewood/summary.json", "lots_index_path": "cities/lakewood/lots/index.json", "hexes_path": "cities/lakewood/hexes.geojson", "boundary_path": "cities/lakewood/boundary.geojson" }, { "id": "cleveland", "name": "Cleveland", "coverage": "partial", "bbox": [ -81.878984, 41.390628, -81.532744, 41.604436 ], "summary_path": "cities/cleveland/summary.json", "lots_index_path": "cities/cleveland/lots/index.json", "hexes_path": "cities/cleveland/hexes.geojson", "boundary_path": "cities/cleveland/boundary.geojson" }, { "id": "shaker_heights", "name": "Shaker Heights", "coverage": "partial", "bbox": [ -81.593724, 41.457152, -81.506914, 41.492952 ], "summary_path": "cities/shaker_heights/summary.json", "lots_index_path": "cities/shaker_heights/lots/index.json", "hexes_path": "cities/shaker_heights/hexes.geojson", "boundary_path": "cities/shaker_heights/boundary.geojson" }, { "id": "parma", "name": "Parma", "coverage": "partial", "bbox": [ -81.785057, 41.350697, -81.684575, 41.419415 ], "summary_path": "cities/parma/summary.json", "lots_index_path": "cities/parma/lots/index.json", "hexes_path": "cities/parma/hexes.geojson", "boundary_path": "cities/parma/boundary.geojson" }, { "id": "university_heights", "name": "University Heights", "coverage": "partial", "bbox": [ -81.556092, 41.486946, -81.516536, 41.503685 ], "summary_path": "cities/university_heights/summary.json", "lots_index_path": "cities/university_heights/lots/index.json", "hexes_path": "cities/university_heights/hexes.geojson", "boundary_path": "cities/university_heights/boundary.geojson" }, { "id": "south_euclid", "name": "South Euclid", "coverage": "partial", "bbox": [ -81.546381, 41.50135, -81.507061, 41.54649 ], "summary_path": "cities/south_euclid/summary.json", "lots_index_path": "cities/south_euclid/lots/index.json", "hexes_path": "cities/south_euclid/hexes.geojson", "boundary_path": "cities/south_euclid/boundary.geojson" }, { "id": "garfield_heights", "name": "Garfield Heights", "coverage": "partial", "bbox": [ -81.638124, 41.384553, -81.567944, 41.441854 ], "summary_path": "cities/garfield_heights/summary.json", "lots_index_path": "cities/garfield_heights/lots/index.json", "hexes_path": "cities/garfield_heights/hexes.geojson", "boundary_path": "cities/garfield_heights/boundary.geojson" }, { "id": "euclid", "name": "Euclid", "coverage": "partial", "bbox": [ -81.553655, 41.545331, -81.48794, 41.635076 ], "summary_path": "cities/euclid/summary.json", "lots_index_path": "cities/euclid/lots/index.json", "hexes_path": "cities/euclid/hexes.geojson", "boundary_path": "cities/euclid/boundary.geojson" }, { "id": "fairview_park", "name": "Fairview Park", "coverage": "partial", "bbox": [ -81.875359, 41.417648, -81.815803, 41.467043 ], "summary_path": "cities/fairview_park/summary.json", "lots_index_path": "cities/fairview_park/lots/index.json", "hexes_path": "cities/fairview_park/hexes.geojson", "boundary_path": "cities/fairview_park/boundary.geojson" } ], "validation": { "method": "A reviewer judged a stratified random sample of single-family lots from aerial imagery, before seeing the screen's answer: is there room behind the house for a ~20 x 20 ft cottage, or a detached garage to convert? Agreement is weighted by each stratum's share of screened lots; lots the screen marks unknown are excluded.", "caveat": "Checks the screen against the same kind of evidence it uses (overhead photos and county building outlines, a few years old). It supports neighborhood-scale totals; it does not certify any single lot.", "as_of": "2026-10-14", "lots_sampled": 300, "lots_reviewed": 300, "agreement": 0.9547, "agreement_ci95": [ 0.9367, 0.9728 ], "cities": [ { "id": "cleveland_heights", "agreement": 0.9787, "agreement_ci95": [ 0.969, 0.9884 ], "lots_judged": 49, "screen_plausible_lots": 12132, "reviewer_implied_plausible_lots": 12482 }, { "id": "lakewood", "agreement": 0.9803, "agreement_ci95": [ 0.9665, 0.9941 ], "lots_judged": 50, "screen_plausible_lots": 8738, "reviewer_implied_plausible_lots": 8920 }, { "id": "cleveland", "agreement": 0.9344, "agreement_ci95": [ 0.9033, 0.9654 ], "lots_judged": 51, "screen_plausible_lots": 67761, "reviewer_implied_plausible_lots": 74461 }, { "id": "shaker_heights", "agreement": 0.9769, "agreement_ci95": [ 0.9665, 0.9874 ], "lots_judged": 49, "screen_plausible_lots": 6587, "reviewer_implied_plausible_lots": 6858 }, { "id": "parma", "agreement": 0.9864, "agreement_ci95": [ 0.979, 0.9937 ], "lots_judged": 51, "screen_plausible_lots": 27019, "reviewer_implied_plausible_lots": 27474 } ] } }