23 Jefferson Ave
San Rafael 94903 · Santa Venetia · Unincorporated Marin · Coordinates: 37.99895, -122.52846
Executive Verdict · Public-Records Synthesis
Zoned RA-B1 in Unincorporated Marin with likely ministerial ADU eligibility and zero mapped flood, fire, or fault hazard overlaps; benchmark value $1,194,000 ($1,051,000–$1,337,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone RA-B1 allows residential use qualifying for ministerial ADU review under state law (4 ADU permits permitted within ¼ mile in 36 months).
Source: Unincorporated Marin zoning · CA Gov. Code 66314
- ✓ Documented permitted upgrades (+$5,120 contributory est.)
Public building records show issued construction/renovation work on this parcel (10 total permits, latest Sep 15, 2026).
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)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: New commercial building at 170 N San Pedro Rd (0.27 mi E, 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 (~$14,181/yr at $1,194,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$1,182/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:
- 7,536 sq ft (0.17 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 23 JEFFERSON AVE
Zoning & Land Use
RA-B1 — Residential Agriculture (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RA-B1 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotCan't tell
Zoned RA-B1 (single-family residential): we can't tell whether it counts as a single-family zone for SB 9. Residential agriculture, estate and restricted: large-lot residential; confirm SB 9 with the county.
- SB 9: split into two lotsCan't tell
Zoned RA-B1 (single-family residential): we can't tell whether it counts as a single-family zone for SB 9. Residential agriculture, estate and restricted: large-lot residential; confirm SB 9 with the county.
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 06041C0457E, effective March 16, 2016
- CGS Alquist-Priolo Earthquake Fault Zone
- Not in an Alquist-Priolo Earthquake Fault Zone
Surrounding Rent & Value Benchmarks (Public Records)
Range: $1,051,000 – $1,337,000 · Status: Off market
HUD Small Area FMR (ZIP 94903) · FY 2026
Studio $2,880 · 1BR $3,450 · 2BR $4,180 · 3BR $5,340 · 4BR $5,530
Developments Deserving Closer Investigation & Active Area Builders
- New commercial building at 170 N San Pedro Rd (Issued)0.27 mi E
Active in "Issued" for 5 yr (first record Dec 1, 2021) with no new permit activity recorded in 4.4 yr. High-impact scale ($18,000,000 declared valuation across 1 permit).
- New commercial building at 10 Ave Of The Flags (Issued)0.36 mi NW
Active in "Issued" for 5.6 yr (first record Mar 26, 2021) with no new permit activity recorded in 5.5 yr. High-impact scale ($2,000,000 declared valuation across 1 permit).
- Accessory dwelling unit at 15 Roosevelt Ave (Applied)0.14 mi NE
In "Applied" for 4.3 yr (since Jul 13, 2022), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
- Accessory dwelling unit at 59 San Pablo Ave (Applied)0.22 mi S
In "Applied" for 2 yr (since Nov 27, 2024), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
Entity-resolved builders & contractors in ½ mile: Tesla Energy (3 on parcel, 3 in ½ mi · Electrical / panel); Yorkshire Roofing (2 on parcel, 2 in ½ mi · Roof replacement); Abc Cooling And Heating (1 on parcel, 1 in ½ mi · HVAC / heat pump); John Owens Services (1 on parcel, 1 in ½ mi · HVAC / heat pump); Haddon Heating And Cooling (1 on parcel, 1 in ½ mi · HVAC / heat pump).
Permit & Project History on This Parcel (10 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B48338 | HVAC / heat pump | Issued | Iss. Sep 15, 2026 | $10,500 | Replace Ductwork |
| B27378 | EV charger | Issued | Iss. Oct 11, 2021 | $1,500 | Install car charger in garage. Run 70A circuit to new subpanel in garage and add 60A breaker and car charger. — New Circ… |
| B23615 | HVAC / heat pump | Issued | Iss. Sep 21, 2020 | $8,755 | A/C Add on, 14 SEER — Mechanical Appliance |
| 156855 | Electrical / panel | Issued | Iss. Oct 24, 2017 | $2,000 | Main Panel Upgr From 200 A To 400 A |
| 156854 | Electrical / panel | Issued | Iss. Oct 24, 2017 | $7,000 |