53 Blackstone Dr
San Rafael 94903 · Marinwood · Unincorporated Marin · Coordinates: 38.03392, -122.54192
Executive Verdict · Public-Records Synthesis
Zoned RMP-6 in Unincorporated Marin with likely ministerial ADU eligibility and zero mapped flood, fire, or fault hazard overlaps; benchmark value $1,268,000 ($1,116,000–$1,420,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone RMP-6 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 (6 total permits, latest Sep 11, 2024).
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)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: 125 new homes (0.3 mi N, 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 (~$15,032/yr at $1,268,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$1,253/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:
- 523 sq ft (0.01 ac)
- Assessor use:
- Single Family Attached
- Addresses on lot:
- 53 BLACKSTONE DR
Zoning & Land Use
RMP-6 — Residential Multiple Planned (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RMP-6 (multifamily residential): state law allows ADUs where homes are allowed. On a multifamily lot the state allowance is different: ADUs in non-living space of the building, plus up to eight detached ADUs.
- SB 9: two homes on the lotUnlikely
Zoned RMP-6 (multifamily residential), not a single-family residential zone.
- SB 9: split into two lotsUnlikely
Zoned RMP-6 (multifamily residential), not a single-family residential zone.
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 X: minimal flood hazard (all of the lot) · FIRM panel 06041C0291D, effective May 4, 2009
- CGS Alquist-Priolo Earthquake Fault Zone
- Not in an Alquist-Priolo Earthquake Fault Zone
Surrounding Rent & Value Benchmarks (Public Records)
Range: $1,116,000 – $1,420,000 · 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
- 125 new homes (Entitled)0.3 mi N
In "Entitled" for 23 mo (since Dec 6, 2024), exceeding the 292d median and 313d 90th percentile for new multifamily / condos / mixed-use permits in Unincorporated Marin (n=21). High-impact scale (125 housing units, 124 deed-restricted affordable across 0 permits).
- New home at 111 Erin Ct (Applied)0.45 mi SW
In "Applied" for 3 yr (since Nov 28, 2023), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121). High-impact scale (1 housing unit, $56,632,994 declared valuation across 1 permit).
- New home at 115 Erin Ct (Applied)0.45 mi SW
In "Applied" for 3 yr (since Nov 28, 2023), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121). High-impact scale (1 housing unit, $55,415,888 declared valuation across 1 permit).
- New home at 3 Erin Dr (Applied)0.45 mi SW
In "Applied" for 3 yr (since Oct 31, 2023), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121). High-impact scale (1 housing unit, $2,993,758 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: Tesla Energy (3 on parcel, 3 in ½ mi · Solar / battery storage); Northern Pacific Roofing (1 on parcel, 1 in ½ mi · Roof replacement); Earth Star Electric (1 on parcel, 1 in ½ mi · Electrical / panel); Owner Builder (38 in ½ mi · Remodel / interior alteration); Owner (30 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (6 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| 177562 | Solar / battery storage | Issued | Iss. Sep 11, 2024 | $500 | Misc - Permanent Removal Of Pv Solar System |
| B20646 | Electrical / panel | Issued | Iss. Dec 20, 2019 | $3,000 | Electrical service upgrade (replacement) 100A, like-for-like. — Service Upgrade |
| 163603 | Electrical / panel | Issued | Iss. Dec 18, 2019 | $2,000 | Electrical Upgrade |
| 163602 | Solar / battery storage | Issued | Iss. Dec 18, 2019 | $11,190 | Rooftop Solar 7.56 K W - Fastrack |
| B17463 | Roof replacement | Issued | Iss. Apr 10, 2019 | $14,000 |