55 A Plaza Dr
Mill Valley 94941 · Alto · Unincorporated Marin · Coordinates: 37.90433, -122.51792
Parcel & Assessor
- Lot size:
- 10,106 sq ft (0.23 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 55A PLAZA DR; 55 PLAZA DR
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 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: $2,138,000 – $2,722,000 · 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 55 Plaza Dr (adu 55a) (Issued)On this parcel
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 30 Shell Rd (Issued)0.15 mi N
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).
- New home at 55 Thomas Dr (Applied)0.33 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).
- New home at 55 S Knoll Rd (Issued)0.43 mi SE
Active in "Issued" for 11.9 yr (first record Dec 22, 2014) with no new permit activity recorded in 11.4 yr. High-impact scale (1 housing unit, $750,000 declared valuation across 1 permit).
Permit & Project History on This Parcel (4 permits, 1 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B45420 | Solar / battery storage | Issued | Iss. Jan 12, 2026 | $6,450 | Remove & Reinstall Existing Solar System |
| 178953 | Accessory dwelling unit (new or conversion) | Issued | Iss. Apr 3, 2025 | $790,000 | Addition & Remodel; Part Conversion Of Lower Lvl To A D U; New Roof Above Rear Deck; New Storage; Sheetrock Garage; Barb… |
| 167095 | Solar / battery storage | Issued | Iss. Feb 8, 2021 | $15,200 | Energy Storage System |
| 155117 | Solar / battery storage | Issued | Iss. Apr 6, 2017 | $27,996 |