530 A Blackstone Dr
San Rafael 94903 · Marinwood · Unincorporated Marin · Coordinates: 38.04040, -122.54997
Executive Verdict · Public-Records Synthesis
Zoned RMP-0.1 in Unincorporated Marin with likely ministerial ADU eligibility and mapped CAL FIRE high fire hazard severity zone (state responsibility area) due diligence; benchmark value $1,255,000 ($1,104,000–$1,406,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone RMP-0.1 allows residential use qualifying for ministerial ADU review under state law.
Source: Unincorporated Marin zoning · CA Gov. Code 66314
- ✓ 5 documented municipal building permits on file
On-parcel permit history is indexed through Oct 9, 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 High 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)
- ! 1 slow or stalled nearby project within ½ mile
Closest lead: 125 new homes (0.48 mi E, 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 (~$14,883/yr at $1,255,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$1,240/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:
- 139,828 sq ft (3.21 ac)
- Assessor use:
- Exemption - Improved
- Addresses on lot:
- 530A BLACKSTONE DR; 530 BLACKSTONE DR
Zoning & Land Use
RMP-0.1 — Residential Multiple Planned (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RMP-0.1 (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-0.1 (multifamily residential), not a single-family residential zone.
- SB 9: split into two lotsUnlikely
Zoned RMP-0.1 (multifamily residential), not a single-family residential zone.
Mapped Hazard Zones on This Lot
- CAL FIRE Fire Hazard Severity Zone
- High Fire Hazard Severity Zone (State Responsibility Area) (all of the lot, map Apr 1, 2024)
- 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: $1,104,000 – $1,406,000 · 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
Nearby Activity (½ mile radius, since November 2024)
3 active or recent development projects (126 housing units across completed, permitted, and pipeline stages) and 131 total building permits recorded within ½ mile.
- New construction4 permits
- Adds housing (ADU)1 permit (1 units)
- Demolition1 permit
- Additions & renovations10 permits
- Building systems92 permits
- Repairs4 permits
- Other19 permits
Developments Deserving Closer Investigation & Active Area Builders
- 125 new homes (Entitled)0.48 mi E
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 530 Blackstone Dr (Issued)On this parcel
High-impact scale ($3,000,000 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: De Mello Roofing (2 on parcel, 2 in ½ mi · Roof replacement); Wormood (1 on parcel, 1 in ½ mi · New multifamily / condos / mixed-use); Owner Builder (16 in ½ mi · Remodel / interior alteration); Owner (14 in ½ mi · Remodel / interior alteration); Roland Franz Construction (2 in ½ mi · Addition (adds square footage)).
Permit & Project History on This Parcel (5 permits, 1 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| 94566 | Other | Applied | App. Oct 9, 2026 | — | Legalize A D U - A B-2533 B W O P Related |
| 94553 | Remodel / interior alteration | Applied | App. Oct 5, 2026 | $10,000 | * B W O P* Non Structural Remodel. New Kitchen In Prayer House. Legalization Of Kitchen In Existing Structure. |
| 180996 | New multifamily / condos / mixed-use | Issued | Iss. Jan 28, 2026 | $3,000,000 | Struct Interior Remod- , New Deck W/Stairs. (N) Driveway "Catholic Charities" |
| B17789 | Roof replacement | Issued | Iss. May 16, 2019 | $12,440 | TEAR-OFF EXISTING BUILT-UP ROOF INSTALL BUILT-UP ROOF CLASS A — ReRoofing |
| 149041 | Roof replacement | Issued | Iss. Sep 21, 2015 | $31,100 | Tear-Off & Re-Roof W/ Comp Shngls |