16 A Shell Rd
Mill Valley 94941 · Alto · Unincorporated Marin · Coordinates: 37.90691, -122.51705
Parcel & Assessor
- Lot size:
- 15,115 sq ft (0.35 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 16A SHELL RD; 16 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 X: minimal flood hazard (all of the lot) · FIRM panel 06041C0467F, 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: $2,285,000 – $2,909,000 · 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
- Accessory dwelling unit at 16 Shell Rd ( Adu 16a) (Issued)On this parcel
Active in "Issued" for 20 mo (first record Mar 7, 2025) with no new permit activity recorded in 15 mo.
- New home at 30 Shell Rd (Issued)480 ft W
Active in "Issued" for 2.3 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)0.18 mi S
Active in "Issued" for 2.5 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).
- New home at 55 Thomas Dr (Applied)0.28 mi E
Active in "Applied" for 6.2 yr (first record Sep 1, 2020) with no new permit activity recorded in 6.2 yr. High-impact scale (1 housing unit, $1,000,000 declared valuation across 1 permit).
Permit & Project History on This Parcel (5 permits, 1 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| 181490 | Windows / doors / siding | Issued | Iss. Apr 16, 2026 | $15,000 | Siding On Accessory Structure |
| 181489 | Electrical / panel | Issued | Iss. Apr 16, 2026 | $12,000 | Automatic Vehicle Gate |
| 181488 | Remodel / interior alteration | Issued | Iss. Apr 16, 2026 | $223,000 | Remodel Kitchen, Bathroom, Laundry; Replace Fireplace; Reroof; Lighting; Repl Main Panel, Gas Meter |
| 179653 | New garage / accessory structure | Issued | Iss. Jul 17, 2025 | $100,000 | Replace Carport With Garage |