73 A Shell Rd
Mill Valley 94941 · Alto · Unincorporated Marin · Coordinates: 37.90602, -122.52384
Executive Verdict · Public-Records Synthesis
Zoned RA-B2 in Unincorporated Marin with likely ministerial ADU eligibility and mapped FEMA AO flood due diligence; benchmark value $2,322,000 ($2,043,000–$2,601,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone RA-B2 allows residential use qualifying for ministerial ADU review under state law (3 ADU permits permitted within ¼ mile in 36 months).
Source: Unincorporated Marin zoning · CA Gov. Code 66314
- ✓ Documented permitted upgrades (+$126,000 contributory est.)
Public building records show issued construction/renovation work on this parcel (1 total permit, latest Jun 24, 2022).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
Watchouts & Due Diligence
- ! FEMA Special Flood Hazard Area (AO, all of the lot of lot)
Zone AO: 1% annual chance flood (Special Flood Hazard Area) overlaps this parcel. Expect mandatory flood insurance for federally backed loans and floodplain elevation/mitigation rules for new units or SB 9 applications.
Source: FEMA National Flood Hazard Layer (parcel polygon)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: 25 new homes (0.49 mi SW, entitled). 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 (~$27,153/yr at $2,322,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,263/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:
- 12,676 sq ft (0.29 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 73A SHELL RD; 73 SHELL RD
Zoning & Land Use
RA-B2 — Residential Agriculture (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RA-B2 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotCan't tell
Zoned RA-B2 (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-B2 (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 AO: 1% annual chance flood (Special Flood Hazard Area) (all of the lot) · FIRM panel 06041C0469F, 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: $2,043,000 – $2,601,000 · Status: Off market
HUD Small Area FMR (ZIP 94941) · FY 2026
Studio $2,730 · 1BR $3,270 · 2BR $3,960 · 3BR $5,060 · 4BR $5,240
Developments Deserving Closer Investigation & Active Area Builders
- 25 new homes (Entitled)0.49 mi SW
In "Entitled" for 3.5 yr (since May 6, 2023), exceeding the 292d median and 313d 90th percentile for new multifamily / condos / mixed-use permits in Unincorporated Marin (n=21). High-impact scale (25 housing units, 6 deed-restricted affordable across 0 permits).
- New home at 30 Shell Rd (Issued)0.29 mi E
Active in "Issued" for 2.4 yr (first record Jul 5, 2024) with no new permit activity recorded in 22 mo. High-impact scale (1 housing unit, $2,800,000 declared valuation across 1 permit).
- Accessory dwelling unit at 55 Plaza Dr (adu 55a) (Issued)0.34 mi E
Active in "Issued" for 2.6 yr (first record Apr 17, 2024) with no new permit activity recorded in 19 mo. High-impact scale (1 housing unit, $790,000 declared valuation across 1 permit).
- Accessory dwelling unit at 70 Shell Rd (Applied)190 ft NE
In "Applied" for 4.2 yr (since Aug 18, 2022), 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: Barker Odonoghue Master Builder (1 on parcel, 1 in ½ mi · Remodel / interior alteration); Owner Builder (18 in ½ mi · Addition (adds square footage)); Owner (9 in ½ mi · Addition (adds square footage)); Kurt Jehling Construction (4 in ½ mi · Remodel / interior alteration); Drosihn Construction (3 in ½ mi · New garage / accessory structure).
Permit & Project History on This Parcel (1 permits, 1 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| 171763 | Remodel / interior alteration | Issued | Iss. Jun 24, 2022 | $400,000 | Remodel; Add A D U; Remodel Garage; Repair Covered Porches; Skylights |
State HCD Housing Element APR records on this parcel: 2 entries (report years 2021, 2022).