San Francisco · Castro/Upper Market · Block/lot 2751/021 · San Francisco
Since October 2024 within ½ mile: 25 homes completed, 17 permitted, 17 proposed or in review; 1 demolition.
40 projects with a record in this window, grouped by us from permits and State housing reports. Units are as proposed on each project's latest record and counted at its current stage.
1,628 permits within ½ mile since October 2024
The map shows new construction, ADUs, demolitions, additions, and renovations. Routine systems work (roofs, HVAC, water heaters) is counted but not mapped. Unit counts are as stated on permits.
Source: San Francisco Department of Building Inspection, Building Permits · Geography: permits located by parcel, ½ mile radius · Retrieved Oct 28, 2026
Permit counts, by the date issued (or applied, if not yet issued). Lot splits are planning cases, which we don't have.
We read public zoning and hazard maps against state law (ADUs: Gov. Code 66314; SB 9: Gov. Code 65852.21 and 66411.7). Local rules, title, tenancy history and site conditions can change the answer. Check with San Francisco's planning department before relying on it.
Sources: San Francisco Planning, Zoning Map – Zoning Districts (retrieved Oct 28, 2026) · CAL FIRE Office of the State Fire Marshal, Fire Hazard Severity Zones in the State Responsibility Area (effective 2024-04-01) (retrieved Oct 26, 2026) · CAL FIRE Office of the State Fire Marshal, Fire Hazard Severity Zones in the Local Responsibility Area (map dated 2025-03-24) (retrieved Oct 26, 2026) · FEMA, National Flood Hazard Layer — flood hazard zones (retrieved Oct 26, 2026) · FEMA, National Flood Hazard Layer — FIRM panels (retrieved Oct 26, 2026) · California Geological Survey, Alquist-Priolo Earthquake Fault Zones (retrieved Oct 26, 2026) · Zoning classes: our classification of RH-3 as multifamily residential, checked against the zone description on Oct 24, 2026
HUD Metro Fair Market Rent · San Francisco, CA HUD Metro FMR Area
HUD FY 2026 · 40th-percentile gross rentCensus ACS 5-year median gross rent (all bedroom counts combined):
Area home-value benchmarks (not an appraisal)
ZIP & neighborhood mediansUnder California Proposition 13, the seller's historical assessed value does not carry over to a buyer. On sale, the parcel is reassessed at the purchase price: 1.00% base rate ($16,700/yr) + local voter-approved bond debt ($3,006/yr) + fixed direct levies/Mello-Roos ($450/yr).
Insurance & hazard context:
−$90,032/yr
Cash needed: $367,400
NOI: $11,301/yr
P&I: $8,444/mo
For $0/mo net cash flow
At $3,600/mo rent
| Scenario | Assumptions | Year 1 Rent | Year 1 Cash Flow | Cash-on-Cash | Break-Even Rent | Year 5 Cash Flow |
|---|---|---|---|---|---|---|
| Conservative | −8% starting rent, +3% vacancy, +3% combined maintenance/CapEx, 1.5%/yr rent growth | $3,312/mo | −$7,916/mo | -25.9% | $14,362/mo | −$7,923/mo |
| Base (your inputs) | Your entered assumptions, 3.0%/yr rent growth | $3,600/mo | −$7,503/mo | -24.5% | $13,293/mo | −$7,305/mo |
| Optimistic (cap-limited) | +6% starting rent, 3% vacancy, 4.2%/yr rent growth (capped by local ordinance ceiling of 4.2%/yr) | $3,816/mo | −$7,265/mo | -23.7% | $12,985/mo | −$6,877/mo |
Rental regulatory context (informational only — not legal advice):
California AB 1482 (Tenant Protection Act, Civ. Code § 1947.12) caps annual rent increases at 5% + local CPI (max 10%) on covered properties. In San Francisco: San Francisco Rent Ordinance (Admin. Code Ch. 37) — annual allowable increase is 60% of Bay Area CPI (capped at 7%) for covered pre-June 1979 buildings. Official program rules ↗
Applied2 unitsAug 7, 2026 – Aug 7, 2026
We group related permits and State housing reports into projects. That grouping is our inference, not an official record.
legalization udu on 1/f and addition of state adu at basement lvl. excavate (e) slab and add (n),convert into habitable space. modify front & side elevations, access stairs & add landscaping. new laundry.
to comply with nov# 202653232: repair deck and stairs, <50%, not street visible.
replace (3) windows with retrofit vinyl windows. not street visible. u-factor <0.30.
Source: San Francisco Department of Building Inspection, Building Permits · Geography: parcel (APN) · Retrieved Oct 28, 2026 · Filed, issued, and status dates come from the Department of Building Inspection, which dates each status change.
No housing activity reported to the State for this parcel (2018–2025 reports).
Source: California HCD, Housing Element Annual Progress Report — Table A2 · Geography: project (parcel) · Retrieved Oct 26, 2026 · From San Francisco's Housing Element Annual Progress Reports. A project can appear in several report years as it moves from entitlement to permit to completion.
Source: San Francisco Planning, Zoning Map – Zoning Districts · Geography: zoning district polygon at parcel point · Retrieved Oct 28, 2026
4345 20TH ST; 4347 20TH ST
Source: San Francisco Planning / DataSF, Parcels – Active and Retired · Geography: parcel · Retrieved Oct 28, 2026
Zoning, permits, planning cases, and assessor data for this lot (SF Planning)
Look up block/lot 2751/021. Assessed value is not market value.
Search by block/lot 2751/021 (SF Treasurer & Tax Collector)
Search building permits, complaints, and inspections by address or block/lot
The official flood hazard map for this location. Our reading of it is under What could be built here.
This site does not show owner names.