665 Butterfield Rd
San Anselmo 94960 · Sleepy Hollow · Unincorporated Marin · Coordinates: 38.00010, -122.57603
Executive Verdict · Public-Records Synthesis
Zoned R1-BD 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 $1,997,000 ($1,757,000–$2,237,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1-BD supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 38,246 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
- ✓ 3 documented municipal building permits on file
On-parcel permit history is indexed through Dec 16, 2021, 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. 16.4 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)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: New home at 830 Butterfield Rd (0.23 mi N, issued). 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 (~$23,416/yr at $1,997,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$1,951/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:
- 38,246 sq ft (0.88 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 665 BUTTERFIELD RD
Zoning & Land Use
R1-BD — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R1-BD (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R1-BD, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1-BD, a single-family residential zone. The lot is 38,246 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: $1,757,000 – $2,237,000 · 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 830 Butterfield Rd (Issued)0.23 mi N
Active in "Issued" for 8.3 yr (first record Aug 9, 2018) with no new permit activity recorded in 7.6 yr. High-impact scale (1 housing unit, $1,097,000 declared valuation across 2 permits).
- New home at 116 Holstein Rd (Issued)0.33 mi SE
Active in "Issued" for 12.9 yr (first record Dec 24, 2013) with no new permit activity recorded in 12.4 yr. High-impact scale (1 housing unit, $800,000 declared valuation across 1 permit).
- Demolition at 111 Deer Hollow Rd (Applied)0.2 mi E
In "Applied" for 6 yr (since Nov 9, 2020), exceeding the 55d median and 261d 90th percentile for demolition permits in Unincorporated Marin (n=130).
- Demolition at 854 Butterfield Ln (Applied)0.26 mi NE
In "Applied" for 2.3 yr (since Aug 1, 2024), exceeding the 55d median and 261d 90th percentile for demolition permits in Unincorporated Marin (n=130).
Entity-resolved builders & contractors in ½ mile: Dan Young Construction (1 on parcel, 1 in ½ mi · Addition (adds square footage)); Ernest Ongaro And Sons (1 on parcel, 1 in ½ mi · HVAC / heat pump); Oconnell Plumbing (1 on parcel, 1 in ½ mi · Plumbing / water heater / sewer); Owner Builder (26 in ½ mi · Remodel / interior alteration); Owner (8 in ½ mi · Addition (adds square footage)).
Permit & Project History on This Parcel (3 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B28106 | HVAC / heat pump | Issued | Iss. Dec 16, 2021 | $9,820 | Replace failed furnace and ducting with new Air handler and ducting, install heat pump new — Replace Ductwork, Mechanica… |
| 143269 | Addition (adds square footage) | Issued | Iss. Jul 9, 2014 | $145,000 | Addition, Interior Remodel, (N) Deck, (N) A/C Condenser T.D. 6/26/14 |
| 142667 | Plumbing / water heater / sewer | Issued | Iss. May 20, 2014 | $7,200 | New Water Service |