2431 Mar East St
Tiburon 94920 · Unincorporated Tiburon · Unincorporated Marin · Coordinates: 37.87750, -122.44440
Executive Verdict · Public-Records Synthesis
Zoned R2 in Unincorporated Marin with likely ministerial ADU eligibility and mapped CAL FIRE moderate fire hazard severity zone (local responsibility area) due diligence; benchmark value $2,998,000 ($2,638,000–$3,358,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone R2 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
- ✓ Documented permitted upgrades (+$17,280 contributory est.)
Public building records show issued construction/renovation work on this parcel (5 total permits, latest Jan 15, 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 (0.46 mi W, 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 (~$34,927/yr at $2,998,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,911/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:
- 5,924 sq ft (0.14 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 2431 MAR EAST ST
Zoning & Land Use
R2 — Residential Two Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R2 (two-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotCan't tell
Zoned R2 (two-family residential): we can't tell whether it counts as a single-family zone for SB 9. Residential Two Family.
- SB 9: split into two lotsCan't tell
Zoned R2 (two-family residential): we can't tell whether it counts as a single-family zone for SB 9. Residential Two Family.
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: $2,638,000 – $3,358,000 · 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)
7 active or recent development projects (7 housing units across completed, permitted, and pipeline stages) and 27 total building permits recorded within ½ mile.
- Additions & renovations3 permits
- Building systems19 permits
- Other5 permits
Developments Deserving Closer Investigation & Active Area Builders
- New home (Entitled)0.46 mi W
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)0.46 mi W
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).
- Accessory dwelling unit at 2398 Vista Del Mar Ln (was 2401 Paradise Dr) (Issued)380 ft W
Active in "Issued" for 6 yr (first record Nov 16, 2020) with no new permit activity recorded in 5.6 yr.
- New home (Issued)480 ft SW
Active in "Issued" for 2 yr (first record Oct 28, 2024) with no new permit activity recorded in 2 yr.
Entity-resolved builders & contractors in ½ mile: Owner (2 on parcel, 4 in ½ mi · Addition (adds square footage)); Earthwise Energy Solutions (2 on parcel, 2 in ½ mi · Electrical / panel); Nc Roofing Solution (1 on parcel, 1 in ½ mi · Roof replacement); Owner Builder (8 in ½ mi · Accessory dwelling unit (new or conversion)); Sausalito Construction (2 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (5 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B45429 | Electrical / panel | Issued | Iss. Jan 15, 2026 | $5,250 | Like for Like Main Panel Replacement |
| B44240 | Solar / battery storage | Issued | Iss. Oct 7, 2025 | $62,870 | 9.1 kW Solar Project including a 30 kWh Battery System |
| B43495 | Plumbing / water heater / sewer | Issued | Iss. Aug 15, 2025 | $400 | Installation of automatic water shut off valve — New Plumbing Fixture(s) |
| B43494 | Electrical / panel | Issued | Iss. Aug 15, 2025 | $700 | Installation of seismic shut off valve to gas meter — New Gas Service |
| B43314 | Roof replacement | Issued | Iss. Aug 1, 2025 | $29,000 | Reroof 2000 sqft install new shingles. 600 sqft Install new torch down — ReRoofing |