172 Cobblestone Dr
San Rafael 94903 · Marinwood · Unincorporated Marin · Coordinates: 38.03556, -122.53872
Executive Verdict · Public-Records Synthesis
Zoned R1 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and zero mapped flood, fire, or fault hazard overlaps; benchmark value $1,380,000 ($1,214,000–$1,546,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 7,971 sq ft lot. Local precedent is active with 2 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$96,800 contributory est.)
Public building records show issued construction/renovation work on this parcel (5 total permits, latest Oct 10, 2023).
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)
- ! Delayed or open permit activity on this parcel
Electrical / panel (91565): Pending in review for 3.1 yr — slower than 90% of electrical / panel permits in Unincorporated Marin (median 0d, 90th pct 2d, n=3,019).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (review-time benchmark)
- ! 4 slow or stalled nearby projects within ½ mile
Closest lead: 125 new homes (0.24 mi NW, 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 (~$16,320/yr at $1,380,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$1,360/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:
- 7,971 sq ft (0.18 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 172 COBBLESTONE DR
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 lotLikely eligible
Zoned R1, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1, a single-family residential zone. The lot is 7,971 sq ft by the assessor, room for two lots of at least 1,200 sq ft, each at least 40% of the original.
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: $1,214,000 – $1,546,000 · 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)0.24 mi NW
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).
- Electrical / panel (91565) (Applied)On this parcel
Pending in review for 3.1 yr — slower than 90% of electrical / panel permits in Unincorporated Marin (median 0d, 90th pct 2d, n=3,019).
- Remodel / interior alteration (174697) (Issued)On this parcel
Issued after 11 mo (3.9× the 83d median) — slower than 90% of remodel / interior alteration permits in Unincorporated Marin (median 83d, 90th pct 266d, n=1,054).
- New commercial building at 200 Marinwood Ave (Applied)0.14 mi SW
Active in "Applied" for 3.9 yr (first record Dec 14, 2022) with no new permit activity recorded in 3.9 yr. High-impact scale ($35,000,000 declared valuation across 2 permits).
Entity-resolved builders & contractors in ½ mile: James Wimmer (2 on parcel, 2 in ½ mi · HVAC / heat pump); Solarcity (1 on parcel, 1 in ½ mi · Solar / battery storage); Deabreu Construction (1 on parcel, 1 in ½ mi · Demolition); Owner Builder (39 in ½ mi · Remodel / interior alteration); Owner (23 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (5 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B35725 | HVAC / heat pump | Issued | Iss. Oct 10, 2023 | $7,500 | Update existing electrical panel with new panel. Move HVAC furnace from existing interior closet to garage. new ductwork… |
| 91565 | Electrical / panel | Applied | App. Oct 10, 2023 | — | Update Elec Service Panel & Move H V A C From Inteior Closet To Garage |
| 174697 | Remodel / interior alteration | Issued | Iss. Aug 7, 2023 | $200,000 | Remodel: Kitchen, Bath, & Dining Room; Relocate Laundry |
| 151872 | Demolition | Issued | Iss. May 5, 2016 | $4,300 | Pool Demo |
| 144088 | Solar / battery storage | Issued | Iss. Sep 10, 2014 |