1 Sulphur Spa Rd
San Anselmo 94960 · Sleepy Hollow · Unincorporated Marin · Coordinates: 38.01545, -122.59613
Executive Verdict · Public-Records Synthesis
Zoned RSP-0.25 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and mapped CAL FIRE moderate fire hazard severity zone (state responsibility area) due diligence; benchmark value $1,792,000 ($1,577,000–$2,007,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned RSP-0.25 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 224,160 sq ft lot. Local precedent is active with 3 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ 6 documented municipal building permits on file
On-parcel permit history is indexed through Nov 6, 2025, 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)
- ✓ Above-average reinvestment in Sleepy Hollow
32 substantial renovation & housing permits over 24 months (32.7 per 1,000 parcels vs. 16.3 citywide baseline) (#4 of 22 neighborhoods).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (Sleepy Hollow)
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 (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)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: New home at 99 Garden Rock Rd (0.16 mi E, applied). 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 (~$21,058/yr at $1,792,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$1,755/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:
- 224,160 sq ft (5.15 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 1 SULPHUR SPA RD
Zoning & Land Use
RSP-0.25 — Residential Single Family Planned (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RSP-0.25 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned RSP-0.25, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned RSP-0.25, a single-family residential zone. The lot is 224,160 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
- Moderate 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 06041C0288D, 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: $1,577,000 – $2,007,000 · Status: Off market
HUD Small Area FMR (ZIP 94960) · FY 2026
Studio $2,510 · 1BR $3,010 · 2BR $3,640 · 3BR $4,650 · 4BR $4,820
Developments Deserving Closer Investigation & Active Area Builders
- New home at 99 Garden Rock Rd (Applied)0.16 mi E
In "Applied" for 3.1 yr (since Oct 11, 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, $1,200,000 declared valuation across 1 permit).
- Demolition at 240 Van Winkle Dr (Applied)0.16 mi S
In "Applied" for 12.2 yr (since Aug 28, 2014), exceeding the 55d median and 261d 90th percentile for demolition permits in Unincorporated Marin (n=130).
- Accessory dwelling unit at 150 Van Winkle Dr (Applied)0.29 mi SE
In "Applied" for 4.6 yr (since Mar 31, 2022), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
- Accessory dwelling unit at 40 Garden Rock Rd (Applied)0.29 mi E
In "Applied" for 5.4 yr (since Jun 8, 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: Peter Levi Plumbing (2 on parcel, 2 in ½ mi · HVAC / heat pump); Ground Up Construction Development (1 on parcel, 1 in ½ mi · Roof replacement); Preferred Plumbing And Drain (1 on parcel, 1 in ½ mi · Plumbing / water heater / sewer); Gagne Brothers Enterprises (1 on parcel, 1 in ½ mi · Plumbing / water heater / sewer); Eco Heating And Air (1 on parcel, 1 in ½ mi · HVAC / heat pump).
Permit & Project History on This Parcel (6 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B44698 | Plumbing / water heater / sewer | Issued | Iss. Nov 6, 2025 | $3,700 | INSTALL TANKLESS WATER HEATER WITH 199K BTUS — Replace Plumbing Fixtures(s) |
| B35880 | HVAC / heat pump | Issued | Iss. Oct 24, 2023 | $20,000 | Replace ductwork in attic and crawlspace. 7 runs in attic and 11 in crawlspace. — Replace Ductwork |
| B20833 | Plumbing / water heater / sewer | Issued | Iss. Jan 20, 2020 | $23,861 | Replacement of Gas line — New Gas Service, Replace Plumbing Fixtures(s) |
| B17667 | Roof replacement | Issued | Iss. May 2, 2019 | $7,500 | Remove and replace aprox 14500 sq ft of roofing material. — ReRoofing |
| 149646 | HVAC / heat pump | Issued |