520 San Geronimo Valley Dr
San Geronimo 94963 · San Geronimo Village · Unincorporated Marin · Coordinates: 38.01368, -122.66435
Executive Verdict · Public-Records Synthesis
Zoned R1-B2-SGV in Unincorporated Marin with likely ADU & SB 9 infill eligibility and mapped CAL FIRE high fire hazard severity zone (state responsibility area) due diligence; benchmark value $1,368,000 ($1,204,000–$1,532,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1-B2-SGV supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 18,774 sq ft lot. Local precedent is active with 3 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$15,663 contributory est.)
Public building records show issued construction/renovation work on this parcel (4 total permits, latest Aug 10, 2023).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
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)
- ! CAL FIRE High Fire Hazard Severity Zone (State Responsibility Area) (all of the lot of lot)
Located in a mapped Fire Hazard Severity Zone. Expect Chapter 7A ignition-resistant building standards, defensible-space inspections, and stricter property insurance underwriting.
Source: CAL FIRE FHSZ (map Apr 1, 2024)
- ! 2 slow or stalled nearby projects within ½ mile
Closest lead: Demolition at 625 San Geronimo Valley Dr (0.18 mi W, issued). Inspect timeline history before assuming near-term completion.
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · HCD APR (½-mile radius)
- ! Year 1 Prop 13 tax reset (~$16,182/yr at $1,368,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$1,349/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:
- 18,774 sq ft (0.43 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 520 SAN GERONIMO VALLEY DR
Zoning & Land Use
R1-B2-SGV — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R1-B2-SGV (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R1-B2-SGV, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1-B2-SGV, a single-family residential zone. The lot is 18,774 sq ft by the assessor, room for two lots of at least 1,200 sq ft, each at least 40% of the original.
Mapped Hazard Zones on This Lot
- CAL FIRE Fire Hazard Severity Zone
- High Fire Hazard Severity Zone (State Responsibility Area) (all of the lot, map Apr 1, 2024)
- FEMA National Flood Hazard Layer
- Zone X: minimal flood hazard (all of the lot) · FIRM panel 06041C0275D, effective May 4, 2009
- CGS Alquist-Priolo Earthquake Fault Zone
- Not in an Alquist-Priolo Earthquake Fault Zone
Surrounding Rent & Value Benchmarks (Public Records)
Range: $1,204,000 – $1,532,000 · Status: Off market
HUD Small Area FMR (ZIP 94963) · FY 2026
Studio $2,500 · 1BR $3,000 · 2BR $3,630 · 3BR $4,630 · 4BR $4,800
Developments Deserving Closer Investigation & Active Area Builders
- Demolition at 625 San Geronimo Valley Dr (Issued)0.18 mi W
Active in "Issued" for 4.9 yr (first record Dec 6, 2021) with no new permit activity recorded in 3.9 yr.
- Accessory dwelling unit at 320 Meadow Way (Applied)0.19 mi W
In "Applied" for 22 mo (since Jan 9, 2025), exceeding the 253d median and 456d 75th percentile for new single-family home permits in Unincorporated Marin (n=121).
- Accessory dwelling unit at 567 San Geronimo Valley Dr (Applied)460 ft W
work_desc changed to "Convert Existing Garage Space To A D U." in snapshot Oct 31, 2026.
- New home at 11 Deer Camp Dr (Applied)0.31 mi S
High-impact scale (1 housing unit, $1,400,000 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: Tesla Energy (2 on parcel, 2 in ½ mi · Roof replacement); Crown Ridge Roofing (1 on parcel, 1 in ½ mi · Roof replacement); Lema Construction (1 on parcel, 1 in ½ mi · Remodel / interior alteration); Owner Builder (5 in ½ mi · Demolition); Dolan Construction (1 in ½ mi · New garage / accessory structure).
Permit & Project History on This Parcel (4 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B35025 | Roof replacement | Issued | Iss. Aug 10, 2023 | $21,450 | tear off existing and reroof with class A composition shingles — ReRoofing |
| 167343 | Roof replacement | Issued | Iss. Mar 9, 2021 | $8,380 | Reroof |
| 167342 | Solar / battery storage | Issued | Iss. Mar 9, 2021 | $26,550 | 5.32kw Rooftop Photovoltaic & Energy Storage System |
| 152358 | Remodel / interior alteration | Issued | Iss. Jun 15, 2016 | $18,500 | 2-Bath Remodel |