2380 Spanish Trail Rd
Tiburon 94920 · Unincorporated Tiburon · Unincorporated Marin · Coordinates: 37.87785, -122.44594
Executive Verdict · Public-Records Synthesis
Zoned R1 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and mapped CAL FIRE moderate fire hazard severity zone (local responsibility area) due diligence; benchmark value $3,262,000 ($2,871,000–$3,653,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 17,990 sq ft lot. Local precedent is active with 2 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$16,560 contributory est.)
Public building records show issued construction/renovation work on this parcel (4 total permits, latest Jul 9, 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)
- ! CAL FIRE Moderate Fire Hazard Severity Zone (Local 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 Mar 24, 2025)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: New home (0.39 mi SW, 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 (~$37,963/yr at $3,262,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$3,164/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:
- 17,990 sq ft (0.41 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 2380 SPANISH TRAIL RD
Zoning & Land Use
R1 — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R1 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R1, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1, a single-family residential zone. The lot is 17,990 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
- Moderate Fire Hazard Severity Zone (Local Responsibility Area) (all of the lot, map Mar 24, 2025)
- FEMA National Flood Hazard Layer
- Zone X: minimal flood hazard (all of the lot) · FIRM panel 06041C0489E, 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: $2,871,000 – $3,653,000 · Status: Off market
HUD Small Area FMR (ZIP 94920) · FY 2026
Studio $2,820 · 1BR $3,380 · 2BR $4,100 · 3BR $5,230 · 4BR $5,420
Developments Deserving Closer Investigation & Active Area Builders
- New home (Entitled)0.39 mi SW
In "Entitled" for 2.2 yr (since Aug 13, 2024), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
- New home (Entitled)0.39 mi SW
In "Entitled" for 2.2 yr (since Aug 13, 2024), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
- Accessory dwelling unit at 2398 Vista Del Mar Ln (was 2401 Paradise Dr) (Issued)130 ft SE
Active in "Issued" for 6 yr (first record Nov 16, 2020) with no new permit activity recorded in 5.6 yr.
- New home at 2448 Spanish Trl Rd Aka (Issued)280 ft N
Active in "Issued" for 8.2 yr (first record Sep 18, 2018) with no new permit activity recorded in 7.5 yr.
Entity-resolved builders & contractors in ½ mile: Chalstrom Builders (1 on parcel, 1 in ½ mi · Remodel / interior alteration); Ilum Solar (1 on parcel, 1 in ½ mi · Solar / battery storage); Dkj Associates (1 on parcel, 1 in ½ mi · Windows / doors / siding); Jemico (1 on parcel, 1 in ½ mi · Windows / doors / siding); Owner Builder (8 in ½ mi · Accessory dwelling unit (new or conversion)).
Permit & Project History on This Parcel (4 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B47447 | Windows / doors / siding | Issued | Iss. Jul 9, 2026 | $7,470 | Non-structural Door/Window Replacement |
| B37320 | Solar / battery storage | Issued | Iss. Mar 13, 2024 | $40,600 | Installing 8.4kw roof mounted solar PV with peak shaving ESS |
| B31798 | Windows / doors / siding | Issued | Iss. Nov 16, 2022 | $11,000 | Replacement of (3) windows, tempered, FF. Wood Clad. Like for like, no change to size or location. — Non-structural Door… |
| 148704 | Remodel / interior alteration | Issued | Iss. Sep 2, 2015 | $127,588 | Rmdl Kit; Move & Add Kitch Wndws |