307 Island Dr
Mill Valley 94941 · Strawberry · Unincorporated Marin · Coordinates: 37.89093, -122.50391
Executive Verdict · Public-Records Synthesis
Zoned RSP-1-BFC in Unincorporated Marin with likely ministerial ADU eligibility and mapped FEMA AE flood due diligence; benchmark value $2,370,000 ($2,086,000–$2,654,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone RSP-1-BFC allows residential use qualifying for ministerial ADU review under state law (1 ADU permit permitted within ¼ mile in 36 months).
Source: Unincorporated Marin zoning · CA Gov. Code 66314
- ✓ 1 documented municipal building permit on file
On-parcel permit history is indexed through Nov 30, 2025, letting you verify roof, HVAC, electrical, or structural work against seller disclosures.
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
- ✓ Above-average reinvestment in Strawberry
43 substantial renovation & housing permits over 24 months (28.4 per 1,000 parcels vs. 16.4 citywide baseline) (#1 of 22 neighborhoods).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (Strawberry)
Watchouts & Due Diligence
- ! FEMA Special Flood Hazard Area (AE, about 48% of the lot of lot)
Zone AE: 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: New home at 218 Meda Ln (0.25 mi NW, applied). 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 (~$27,705/yr at $2,370,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,309/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:
- 37,244 sq ft (0.86 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 307 ISLAND DR; 309 ISLAND DR
Zoning & Land Use
RSP-1-BFC — Residential Single Family Planned (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RSP-1-BFC (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotPossible, with conditions
Zoned RSP-1-BFC, a single-family residential zone. FEMA Special Flood Hazard Area (Zone AE) covers about 48% of the lot: the project must meet the National Flood Insurance Program floodplain standards, or the lot needs a map revision.
- SB 9: split into two lotsPossible, with conditions
Zoned RSP-1-BFC, a single-family residential zone. The lot is 37,244 sq ft by the assessor, room for two lots of at least 1,200 sq ft, each at least 40% of the original. FEMA Special Flood Hazard Area (Zone AE) covers about 48% of the lot: the project must meet the National Flood Insurance Program floodplain standards, or the lot needs a map revision.
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 AE: 1% annual chance flood (Special Flood Hazard Area) (about 48% of the lot); Zone X: minimal flood hazard (about 52% 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: $2,086,000 – $2,654,000 · 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 218 Meda Ln (Applied)0.25 mi NW
In "Applied" for 6.5 yr (since Apr 30, 2020), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121). High-impact scale (1 housing unit, $850,000 declared valuation across 1 permit).
- New home at 82 Vista Del Sol (Issued)0.45 mi NW
Active in "Issued" for 12.3 yr (first record Aug 7, 2014) with no new permit activity recorded in 12.1 yr. High-impact scale (1 housing unit, $1,000,000 declared valuation across 1 permit).
- New home at 153 Richardson Dr (adu 153a) (Issued)0.49 mi N
Active in "Issued" for 3.4 yr (first record Jun 5, 2023) with no new permit activity recorded in 16 mo. High-impact scale (1 housing unit, $1,493,000 declared valuation across 1 permit).
- New commercial building at 118 E Strawberry Dr (Applied)0.5 mi N
Active in "Applied" for 8.1 yr (first record Oct 3, 2018) with no new permit activity recorded in 8.1 yr. High-impact scale ($1,600,000 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: Tech Air (1 on parcel, 1 in ½ mi · HVAC / heat pump); Regency General Contractors (151 in ½ mi · Remodel / interior alteration); Owner Builder (39 in ½ mi · Remodel / interior alteration); Owner (33 in ½ mi · Remodel / interior alteration); Lek Enterprises (24 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (1 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B44951 | HVAC / heat pump | Issued | Iss. Nov 30, 2025 | $15,250 | Replace furnace and ducting — Mechanical Appliance |