23 Heron Dr
Mill Valley 94941 · Strawberry · Unincorporated Marin · Coordinates: 37.87983, -122.49742
Executive Verdict · Public-Records Synthesis
Zoned RMP-4-BFC in Unincorporated Marin with likely ministerial ADU eligibility and zero mapped flood, fire, or fault hazard overlaps; benchmark value $2,280,000 ($2,006,000–$2,554,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone RMP-4-BFC allows residential use qualifying for ministerial ADU review under state law.
Source: Unincorporated Marin zoning · CA Gov. Code 66314
- ✓ 5 documented municipal building permits on file
On-parcel permit history is indexed through Feb 1, 2022, 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
- ! 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 (0.25 mi NW, 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 (~$26,670/yr at $2,280,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,223/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:
- 14,767 sq ft (0.34 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 23 HERON DR
Zoning & Land Use
RMP-4-BFC — Residential Multiple Planned (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RMP-4-BFC (multifamily residential): state law allows ADUs where homes are allowed. On a multifamily lot the state allowance is different: ADUs in non-living space of the building, plus up to eight detached ADUs.
- SB 9: two homes on the lotUnlikely
Zoned RMP-4-BFC (multifamily residential), not a single-family residential zone.
- SB 9: split into two lotsUnlikely
Zoned RMP-4-BFC (multifamily residential), not a single-family residential zone.
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 06041C0488E, 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: $2,006,000 – $2,554,000 · 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 (Entitled)0.25 mi NW
In "Entitled" for 5.1 yr (since Sep 30, 2021), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
- Demolition at 171 Great Cir Dr (Applied)0.28 mi NW
In "Applied" for 15 mo (since Aug 14, 2025), exceeding the 55d median and 261d 90th percentile for demolition permits in Unincorporated Marin (n=130).
- New home at 61 Liberty Dock (Applied)0.47 mi SW
In "Applied" for 11.5 yr (since May 6, 2015), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
- New home at 2 Nina Ct (Issued)250 ft SW
Active in "Issued" for 3.9 yr (first record Dec 9, 2022) with no new permit activity recorded in 13 mo.
Entity-resolved builders & contractors in ½ mile: San Francisco Investment (1 on parcel, 2 in ½ mi · New garage / accessory structure); Building Efficiency (1 on parcel, 1 in ½ mi · HVAC / heat pump); Sustainable Living Builders (1 on parcel, 1 in ½ mi · Roof replacement); Divine Electric (1 on parcel, 1 in ½ mi · Electrical / panel); Evcharge4u (1 on parcel, 1 in ½ mi · EV charger).
Permit & Project History on This Parcel (5 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B28492 | Electrical / panel | Issued | Iss. Feb 1, 2022 | $1,958 | -Add manual transfer switch and 30A inlet at exterior of Garage for 4 Circuit transfer switch — New Circuits / Outlets |
| B28048 | HVAC / heat pump | Issued | Iss. Dec 8, 2021 | $35,000 | Change-Out and install (2) new high furnace and air conditioner — Replace Mechanical Appliance |
| B27931 | Roof replacement | Issued | Iss. Nov 30, 2021 | $27,530 | Removal of the current flat roof, installation of Polyglass 2 ply roofing system, 2680 square feet. — ReRoofing |
| 169888 | New garage / accessory structure | Issued | Iss. Nov 12, 2021 | $65,000 | Remove Stair; Add Elevator |
| B13864 | EV charger |