3 Heatherstone Ln
San Rafael 94903 · Marinwood · Unincorporated Marin · Coordinates: 38.04203, -122.54137
Executive Verdict · Public-Records Synthesis
Zoned RMP-0.1 in Unincorporated Marin with likely ministerial ADU eligibility and mapped CAL FIRE high fire hazard severity zone (state responsibility area) due diligence; benchmark value $1,411,000 ($1,242,000–$1,580,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone RMP-0.1 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
- ✓ Documented permitted upgrades (+$12,088 contributory est.)
Public building records show issued construction/renovation work on this parcel (1 total permit, latest Sep 10, 2025).
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)
- ! CAL FIRE High Fire Hazard Severity Zone (State Responsibility Area) (all of the lot of lot)
Located in a mapped Fire Hazard Severity Zone. Expect Chapter 7A ignition-resistant building standards, defensible-space inspections, and stricter property insurance underwriting.
Source: CAL FIRE FHSZ (map Apr 1, 2024)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: 125 new homes (0.26 mi S, 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 (~$16,677/yr at $1,411,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$1,390/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:
- 70,393 sq ft (1.62 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 3 HEATHERSTONE LN
Zoning & Land Use
RMP-0.1 — Residential Multiple Planned (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RMP-0.1 (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-0.1 (multifamily residential), not a single-family residential zone.
- SB 9: split into two lotsUnlikely
Zoned RMP-0.1 (multifamily residential), not a single-family residential zone.
Mapped Hazard Zones on This Lot
- CAL FIRE Fire Hazard Severity Zone
- High Fire Hazard Severity Zone (State Responsibility Area) (all of the lot, map Apr 1, 2024)
- FEMA National Flood Hazard Layer
- Zone X: minimal flood hazard (all of the lot) · FIRM panel 06041C0291D, effective May 4, 2009
- CGS Alquist-Priolo Earthquake Fault Zone
- Not in an Alquist-Priolo Earthquake Fault Zone
Surrounding Rent & Value Benchmarks (Public Records)
Range: $1,242,000 – $1,580,000 · Status: Off market
HUD Small Area FMR (ZIP 94903) · FY 2026
Studio $2,880 · 1BR $3,450 · 2BR $4,180 · 3BR $5,340 · 4BR $5,530
Developments Deserving Closer Investigation & Active Area Builders
- 125 new homes (Entitled)0.26 mi S
In "Entitled" for 23 mo (since Dec 6, 2024), exceeding the 292d median and 313d 90th percentile for new multifamily / condos / mixed-use permits in Unincorporated Marin (n=21). High-impact scale (125 housing units, 124 deed-restricted affordable across 0 permits).
- Accessory dwelling unit at 2558 Heatherstone Dr (Applied)0.41 mi S
In "Applied" for 5.5 yr (since Apr 29, 2021), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
- Demolition at 249 Johnstone Dr (Issued)0.21 mi SE
Active in "Issued" for 8.7 yr (first record Mar 15, 2018) with no new permit activity recorded in 8.6 yr.
- New home at 251 Johnstone Ct (Issued)0.22 mi SE
Active in "Issued" for 8.4 yr (first record Jun 12, 2018) with no new permit activity recorded in 7.7 yr.
Entity-resolved builders & contractors in ½ mile: Empower Solar (1 on parcel, 1 in ½ mi · Solar / battery storage); Owner Builder (29 in ½ mi · Remodel / interior alteration); Owner (19 in ½ mi · Remodel / interior alteration); Kl Construction (3 in ½ mi · Addition (adds square footage)); Swan Pools (3 in ½ mi · Pool / spa).
Permit & Project History on This Parcel (1 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B43808 | Solar / battery storage | Issued | Iss. Sep 10, 2025 | $27,982 | 24 module 9.72 kWDC Roof Mount Solar / (1) Tesla Powerwall 3 Battery / (N) Tesla Backup Switch (1624171-XX-Y) |