273 Greene St
Mill Valley 94941 · Almonte · Unincorporated Marin · Coordinates: 37.88207, -122.52788
Executive Verdict · Public-Records Synthesis
Zoned R1-B1 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and zero mapped flood, fire, or fault hazard overlaps; benchmark value $2,116,000 ($1,862,000–$2,370,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1-B1 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 6,882 sq ft lot. Local precedent is active with 11 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$13,200 contributory est.)
Public building records show issued construction/renovation work on this parcel (6 total permits, latest Jan 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 home at 217 Cleveland Ave (0.21 mi N, 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 (~$24,784/yr at $2,116,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,065/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:
- 6,882 sq ft (0.16 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 273 GREENE ST
Zoning & Land Use
R1-B1 — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R1-B1 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R1-B1, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1-B1, a single-family residential zone. The lot is 6,882 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
- 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: $1,862,000 – $2,370,000 · 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
- New home at 217 Cleveland Ave (Issued)0.21 mi N
Active in "Issued" for 9.7 yr (first record Feb 21, 2017) with no new permit activity recorded in 2.3 yr. High-impact scale (1 housing unit, $875,000 declared valuation across 1 permit).
- Accessory dwelling unit at 131 Yale Ave A (Issued)0.41 mi N
Active in "Issued" for 4.8 yr (first record Jan 19, 2022) with no new permit activity recorded in 3.4 yr. High-impact scale (1 housing unit, $1,000,000 declared valuation across 1 permit).
- New home at 249 Perry St (Applied)0.12 mi NE
In "Applied" for 2 yr (since Oct 31, 2024), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
- Accessory dwelling unit at 242 Morning Sun Ave (Applied)0.15 mi NE
In "Applied" for 2 yr (since Nov 21, 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: I Construction And Structural (1 on parcel, 1 in ½ mi · New garage / accessory structure); Able Roofing (1 on parcel, 1 in ½ mi · Roof replacement); Renewal By Andersen (1 on parcel, 1 in ½ mi · Windows / doors / siding); Divine Electric (1 on parcel, 1 in ½ mi · EV charger); Fwh Acquisition (1 on parcel, 1 in ½ mi · Plumbing / water heater / sewer).
Permit & Project History on This Parcel (6 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B45497 | Roof replacement | Issued | Iss. Jan 15, 2026 | $23,175 | REMOVE AND REPLACE CLASS A COMP SHINGLE ROOF. — ReRoofing; With Electronic Inspection |
| 171622 | New garage / accessory structure | Issued | Iss. Jun 9, 2022 | $60,000 | Repair/Replace [E] Car Deck |
| 167100 | Remodel / interior alteration | Issued | Iss. Feb 8, 2021 | $30,000 | Bath Rmdl |
| B20217 | Plumbing / water heater / sewer | Issued | Iss. Oct 29, 2019 | $1,640 | REMOVE/REPLACE GAS WATER HEATER — Replace Plumbing Fixtures(s) |
| B19942 | EV charger | Issued | Iss. Sep 24, 2019 |