1618 Mason St
San Francisco · Chinatown · San Francisco · Coordinates: 37.79855, -122.41171
Executive Verdict · Public-Records Synthesis
Zoned RM-2 in San Francisco with likely ministerial ADU eligibility and zero mapped flood, fire, or fault hazard overlaps; benchmark value $1,876,000 ($1,595,000–$2,157,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone RM-2 allows residential use qualifying for ministerial ADU review under state law (14 ADU permits permitted within ¼ mile in 36 months).
Source: San Francisco zoning · CA Gov. Code 66314
- ✓ Documented permitted upgrades (+$414,739 contributory est.)
Public building records show issued construction/renovation work on this parcel (12 total permits, latest May 22, 2026).
Source: San Francisco Department of Building Inspection, Building Permits (parcel APN)
- ✓ Above-average reinvestment in Chinatown
284 substantial renovation & housing permits over 24 months (283.7 per 1,000 parcels vs. 91.4 citywide baseline) (#12 of 37 neighborhoods).
Source: San Francisco Department of Building Inspection, Building Permits (Chinatown)
Watchouts & Due Diligence
- ! Mapped flood awareness zone (Zone X: minimal flood hazard)
all of the lot of the parcel intersects Zone X: minimal flood hazard. Outside mandatory federal SFHA insurance rules, but check local drainage and finished-floor requirements.
Source: FEMA National Flood Hazard Layer (parcel polygon)
- ! Delayed or open permit activity on this parcel
Accessory dwelling unit at 1632 Mason St: Active in "Issued" for 5.6 yr (first record Apr 19, 2021) with no new permit activity recorded in 4.4 yr.
Source: San Francisco Department of Building Inspection, Building Permits (review-time benchmark)
- ! 4 slow or stalled nearby projects within ½ mile
Closest lead: 425 Broadway (Mod) (0.41 mi E, entitled). Inspect timeline history before assuming near-term completion.
Source: San Francisco Department of Building Inspection, Building Permits · HCD APR (½-mile radius)
- ! Year 1 Prop 13 tax reset (~$22,587/yr at $1,876,000)
Sale triggers reassessment to 1.00% base + ~0.18% voter debt (~$1,882/mo). Confirm exact Mello-Roos / CFD special assessments on the county tax bill.
Source: CA Const. Art. XIIIA (Prop 13) · County Tax Collector
Parcel & Assessor
- Lot size:
- —
- Assessor use:
- —
- Addresses on lot:
- 1618 MASON ST; 1632 MASON ST
Zoning & Land Use
RM-2 — RESIDENTIAL- MIXED, MODERATE DENSITY (Residential)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RM-2 (multifamily residential): state law allows ADUs where homes are allowed. On a multifamily lot the state allowance is different: ADUs in non-living space of the building, plus up to eight detached ADUs.
- SB 9: two homes on the lotUnlikely
Zoned RM-2 (multifamily residential), not a single-family residential zone.
- SB 9: split into two lotsUnlikely
Zoned RM-2 (multifamily residential), not a single-family residential zone.
Mapped Hazard Zones on This Lot
- CAL FIRE Fire Hazard Severity Zone
- Not in a State-mapped fire hazard severity zone
- FEMA National Flood Hazard Layer
- Zone X: minimal flood hazard (all of the lot) · FIRM panel 0602980116A, effective March 23, 2021
- CGS Alquist-Priolo Earthquake Fault Zone
- Not in an Alquist-Priolo Earthquake Fault Zone
Surrounding Rent & Value Benchmarks (Public Records)
Range: $1,595,000 – $2,157,000 · Status: Off market
HUD Metro FMR (San Francisco, CA HUD Metro FMR Area) · FY 2026
Studio $2,485 · 1BR $2,977 · 2BR $3,604 · 3BR $4,604 · 4BR $4,772
Nearby Activity (½ mile radius, since November 2024)
52 active or recent development projects (502 housing units across completed, permitted, and pipeline stages) and 1,984 total building permits recorded within ½ mile.
- New construction2 permits (177 units)
- Adds housing (ADU)33 permits (57 units)
Developments Deserving Closer Investigation & Active Area Builders
- Accessory dwelling unit at 1632 Mason St (Issued)On this parcel
Active in "Issued" for 5.6 yr (first record Apr 19, 2021) with no new permit activity recorded in 4.4 yr.
- Accessory dwelling unit at 1618 Mason St (Issued)On this parcel
Active in "Issued" for 5.6 yr (first record Apr 9, 2021) with no new permit activity recorded in 4.5 yr.
- 425 Broadway (Mod) (Entitled)0.41 mi E
Active in "Entitled" for 16 mo (first record Jul 10, 2025) with no new permit activity recorded in 16 mo. High-impact scale (75 housing units across 0 permits).
- 28 new homes (Entitled)0.47 mi S
Active in "Entitled" for 2.1 yr (first record Sep 26, 2024) with no new permit activity recorded in 2.1 yr. High-impact scale (28 housing units, 5 deed-restricted affordable across 0 permits).
Permit & Project History on This Parcel (12 permits, 2 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| 202605221767 | Roof replacement | complete | Iss. May 22, 2026 | $60,000 | reroof hot works. |
| 202104198852 | Accessory dwelling unit (new or conversion) | issued | Iss. Jul 1, 2022 | $195,000 | addition of (1) adu in existing basement. |
| 202104098281 | Accessory dwelling unit (new or conversion) | issued | Iss. Jun 1, 2022 | $275,000 | addition of (2) adu's in existing basement. |
| M1021167 |