215 Mark Twain Ave
San Rafael 94903 · Santa Venetia · Unincorporated Marin · Coordinates: 38.00540, -122.52476
Executive Verdict · Public-Records Synthesis
Zoned R1 in Unincorporated Marin with likely ministerial ADU eligibility and mapped FEMA AE flood due diligence; benchmark value $1,227,000 ($1,080,000–$1,374,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone R1 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 (+$13,120 contributory est.)
Public building records show issued construction/renovation work on this parcel (4 total permits, latest Jun 5, 2023).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
Watchouts & Due Diligence
- ! FEMA Special Flood Hazard Area (AE, about 24% of the lot of lot)
Zone AE: 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)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: New home at 16 Crestview Way (0.41 mi NE, 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 (~$14,561/yr at $1,227,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$1,213/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:
- 9,845 sq ft (0.23 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 215 MARK TWAIN AVE
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 lotPossible, with conditions
Zoned R1, a single-family residential zone. FEMA Special Flood Hazard Area (Zone AE) covers about 24% 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 R1, a single-family residential zone. The lot is 9,845 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 AE) covers about 24% 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
- Not in a State-mapped fire hazard severity zone
- FEMA National Flood Hazard Layer
- Zone AE: 1% annual chance flood (Special Flood Hazard Area) (about 24% of the lot); Zone X: 0.2% annual chance flood hazard (shaded X) (about 76% of the lot) · FIRM panel 06041C0294E, 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: $1,080,000 – $1,374,000 · 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
- New home at 16 Crestview Way (Issued)0.41 mi NE
Active in "Issued" for 2.5 yr (first record May 20, 2024) with no new permit activity recorded in 15 mo. High-impact scale (1 housing unit, $770,000 declared valuation across 1 permit).
- New commercial building at 170 N San Pedro Rd (Issued)0.42 mi S
Active in "Issued" for 4.9 yr (first record Dec 1, 2021) with no new permit activity recorded in 4.4 yr. High-impact scale ($18,000,000 declared valuation across 1 permit).
- Demolition at 13 Edward Ave (Applied)0.28 mi S
In "Applied" for 3.8 yr (since Jan 23, 2023), exceeding the 55d median and 261d 90th percentile for demolition permits in Unincorporated Marin (n=130).
- Accessory dwelling unit at 321 N San Pedro Rd (Applied)0.3 mi NE
In "Applied" for 5.8 yr (since Feb 9, 2021), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
Entity-resolved builders & contractors in ½ mile: Sunpower (1 on parcel, 1 in ½ mi · Solar / battery storage); Tesla Energy Operations (1 on parcel, 1 in ½ mi · Solar / battery storage); Lcx Energy (1 on parcel, 1 in ½ mi · Electrical / panel); ARS Rescue Rooter (1 on parcel, 1 in ½ mi · Plumbing / water heater / sewer); Owner Builder (38 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (4 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B34165 | Electrical / panel | Issued | Iss. Jun 5, 2023 | $5,675 | Electrical service panel replacement 200A Electrical sub-panel 200A for existing loads. — Service Upgrade |
| B33686 | Solar / battery storage | Issued | Iss. May 1, 2023 | $8,880 | Install roof mount solar panels at 6 kW and battery |
| 164448 | Solar / battery storage | Issued | Iss. Mar 11, 2020 | $14,000 | Rooftop Solar 3.50 K W - Express |
| 150442 | Plumbing / water heater / sewer | Issued | Iss. Jan 20, 2016 | $1,500 | Sewer Cleanout |