2490 Spanish Trail Rd
Tiburon 94920 · Unincorporated Tiburon · Unincorporated Marin · Coordinates: 37.87901, -122.44655
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 $3,128,000 ($2,753,000–$3,503,000).
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 11,021 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
- ✓ 2 documented municipal building permits on file
On-parcel permit history is indexed through Mar 22, 2026, 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)
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 (0.41 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 (~$36,422/yr at $3,128,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$3,035/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:
- 11,021 sq ft (0.25 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 2490 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 11,021 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: $2,753,000 – $3,503,000 · 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
Nearby Activity (½ mile radius, since November 2024)
9 active or recent development projects (9 housing units across completed, permitted, and pipeline stages) and 34 total building permits recorded within ½ mile.
- New construction1 permit
- Additions & renovations3 permits
- Building systems24 permits
- Repairs1 permit
- Other5 permits
Developments Deserving Closer Investigation & Active Area Builders
- New home (Entitled)0.41 mi SW
In "Entitled" for 2.3 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)0.41 mi SW
In "Entitled" for 2.3 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 at 2448 Spanish Trl Rd Aka (Issued)170 ft SE
Active in "Issued" for 8.2 yr (first record Sep 18, 2018) with no new permit activity recorded in 7.5 yr.
- Accessory dwelling unit at 2398 Vista Del Mar Ln (was 2401 Paradise Dr) (Issued)0.11 mi SE
Active in "Issued" for 6 yr (first record Nov 16, 2020) with no new permit activity recorded in 5.6 yr.
Entity-resolved builders & contractors in ½ mile: Xmag Construction (1 on parcel, 1 in ½ mi · Other); Ernest Ongaro And Sons (1 on parcel, 1 in ½ mi · Plumbing / water heater / sewer); Owner Builder (8 in ½ mi · Accessory dwelling unit (new or conversion)); Owner (2 in ½ mi · Addition (adds square footage)); Kelly Domer Partners Dba Pacific Constr (2 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (2 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B46261 | Other | Issued | Iss. Mar 22, 2026 | $50,000 | — |
| B36910 | Plumbing / water heater / sewer | Issued | Iss. Feb 5, 2024 | $2,500 | Replaced failed tank wh, Installed new 50 Gal WH in same location — Replace Plumbing Fixtures(s) |