2580 Mar East St
Tiburon 94920 · Unincorporated Tiburon · Unincorporated Marin · Coordinates: 37.88015, -122.44337
Executive Verdict · Public-Records Synthesis
Zoned RSP-5.8-BFC in Unincorporated Marin with likely ministerial ADU eligibility and mapped FEMA VE flood / CAL FIRE moderate fire hazard severity zone (state responsibility area) due diligence; benchmark value $3,095,000 ($2,724,000–$3,466,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone RSP-5.8-BFC allows residential use qualifying for ministerial ADU review under state law (2 ADU permits 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 Oct 20, 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)
Watchouts & Due Diligence
- ! FEMA Special Flood Hazard Area (VE, about 41% of the lot of lot)
Zone VE: 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)
- ! CAL FIRE Moderate 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: New home at 2448 Spanish Trl Rd Aka (0.19 mi SW, issued). 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 (~$36,043/yr at $3,095,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$3,004/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:
- 9,583 sq ft (0.22 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 2580 MAR EAST ST
Zoning & Land Use
RSP-5.8-BFC — Residential Single Family Planned (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RSP-5.8-BFC (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotPossible, with conditions
Zoned RSP-5.8-BFC, a single-family residential zone. FEMA Special Flood Hazard Area (Zone VE) covers about 41% 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-5.8-BFC, a single-family residential zone. The lot is 9,583 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 VE) covers about 41% 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
- Moderate Fire Hazard Severity Zone (State Responsibility Area) (all of the lot, map Apr 1, 2024)
- FEMA National Flood Hazard Layer
- Zone VE: 1% annual chance flood (Special Flood Hazard Area) (about 41% of the lot); Zone X: minimal flood hazard (about 59% 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: $2,724,000 – $3,466,000 · 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 at 2448 Spanish Trl Rd Aka (Issued)0.19 mi SW
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)0.22 mi SW
Active in "Issued" for 6 yr (first record Nov 16, 2020) with no new permit activity recorded in 5.6 yr.
- New home (Issued)0.26 mi SW
Active in "Issued" for 2 yr (first record Oct 28, 2024) with no new permit activity recorded in 2 yr.
- New home (Issued)0.34 mi SW
Active in "Issued" for 22 mo (first record Jan 14, 2025) with no new permit activity recorded in 22 mo.
Entity-resolved builders & contractors in ½ mile: Freemodel (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); Sausalito Construction (2 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (1 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B44383 | Plumbing / water heater / sewer | Issued | Iss. Oct 20, 2025 | $15,000 | Remove existing alcove tub in Primary Bathroom and replace it with a freestanding tub. Re-tile the floor under the tub. |