1433 Butterfield Rd
San Anselmo 94960 · Sleepy Hollow · Unincorporated Marin · Coordinates: 38.01434, -122.58603
Executive Verdict · Public-Records Synthesis
Zoned RSP-1 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 $2,071,000 ($1,822,000–$2,320,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned RSP-1 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 43,255 sq ft lot. Local precedent is active with 1 ADU permit within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$74,680 contributory est.)
Public building records show issued construction/renovation work on this parcel (7 total permits, latest Oct 16, 2025).
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. 16.4 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)
- ! Delayed or open permit activity on this parcel
Windows / doors / siding (178422): Issued after 3 mo — slower than 90% of windows / doors / siding permits in Unincorporated Marin (median 0d, 90th pct 5d, n=1,476).
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: New home at 99 Garden Rock Rd (0.4 mi W, 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)
Parcel & Assessor
- Lot size:
- 43,255 sq ft (0.99 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 1433 BUTTERFIELD RD
Zoning & Land Use
RSP-1 — Residential Single Family Planned (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RSP-1 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned RSP-1, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned RSP-1, a single-family residential zone. The lot is 43,255 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 06041C0289D, 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: $1,822,000 – $2,320,000 · 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)0.4 mi W
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).
- Windows / doors / siding (178422) (Issued)On this parcel
Issued after 3 mo — slower than 90% of windows / doors / siding permits in Unincorporated Marin (median 0d, 90th pct 5d, n=1,476).
- Solar / battery storage (91868) (Applied)On this parcel
Pending in review for 2.8 yr — slower than 90% of solar / battery storage permits in Unincorporated Marin (median 0d, 90th pct 2d, n=2,977).
- New commercial building at 1500 Butterfield Rd (Issued)0.17 mi N
Active in "Issued" for 4 yr (first record Oct 25, 2022) with no new permit activity recorded in 12 mo. High-impact scale ($2,700,000 declared valuation across 2 permits).
Entity-resolved builders & contractors in ½ mile: Avila And Wadlington Contractors (1 on parcel, 2 in ½ mi · New garage / accessory structure); Ernest Ongaro And Sons (2 on parcel, 2 in ½ mi · HVAC / heat pump); Robert Federighi (1 on parcel, 1 in ½ mi · Windows / doors / siding); Sunshine Roofing (1 on parcel, 1 in ½ mi · Roof replacement); Distribugen (1 on parcel, 1 in ½ mi · Solar / battery storage).
Permit & Project History on This Parcel (7 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B44403 | HVAC / heat pump | Issued | Iss. Oct 16, 2025 | $18,000 | Replace furnace and AC w/ air handler and heat pump — Replace Mechanical Appliance |
| 178422 | Windows / doors / siding | Issued | Iss. Jan 16, 2025 | $254,215 | Replace Windows, Doors, Garage Door - Sheetrock & Siding Only In Areas Affected By Window Work |
| B36866 | Solar / battery storage | Issued | Iss. Feb 15, 2024 | $15,000 | 7kw roof mount solar array with energy storage system(3 Tesla powerwalls) |
| 91868 | Solar / battery storage | Applied | App. Jan 30, 2024 | — | 7.6kw Rooftop Photovoltaic & Energy Storage System |
| B35721 | Roof replacement | Issued |