667 Butterfield Rd
San Anselmo 94960 · Sleepy Hollow · Unincorporated Marin · Coordinates: 38.00037, -122.57584
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 $2,129,000 ($1,874,000–$2,384,000).
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 39,465 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
- ✓ Documented permitted upgrades (+$132,200 contributory est.)
Public building records show issued construction/renovation work on this parcel (6 total permits, latest Apr 22, 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
Pool / spa (92406): Pending in review for 2.3 yr (6.2× the 136d median) — slower than 90% of pool / spa permits in Unincorporated Marin (median 136d, 90th pct 393d, n=162).
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 830 Butterfield Rd (0.21 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)
Parcel & Assessor
- Lot size:
- 39,465 sq ft (0.91 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 667 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 39,465 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: $1,874,000 – $2,384,000 · 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
- Pool / spa (92406) (Applied)On this parcel
Pending in review for 2.3 yr (6.2× the 136d median) — slower than 90% of pool / spa permits in Unincorporated Marin (median 136d, 90th pct 393d, n=162).
- Remodel / interior alteration (174248) (Issued)On this parcel
Issued after 11 mo (4.2× the 83d median) — slower than 90% of remodel / interior alteration permits in Unincorporated Marin (median 83d, 90th pct 266d, n=1,054).
- New home at 830 Butterfield Rd (Issued)0.21 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).
Entity-resolved builders & contractors in ½ mile: Owner Builder (3 on parcel, 26 in ½ mi · Remodel / interior alteration); Tesla Energy Operations (1 on parcel, 1 in ½ mi · Solar / battery storage); Lutz Electric (1 on parcel, 1 in ½ mi · Electrical / panel); Owner (8 in ½ mi · Addition (adds square footage)); Summit Professional Builders (4 in ½ mi · New garage / accessory structure).
Permit & Project History on This Parcel (6 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B42119 | Solar / battery storage | Issued | Iss. Apr 22, 2025 | $14,000 | Install 2 battery backups |
| B39633 | Electrical / panel | Issued | Iss. Sep 29, 2024 | $8,000 | New 400 amp main service panel with overhead mast. Remove existing Zinsco sub panel @ garage ( safety issue ) — New Circ… |
| 92406 | Pool / spa | Applied | App. Jul 17, 2024 | $75,000 | Pool; Stairs Between Pool And House |
| 174250 | New garage / accessory structure | Issued | Iss. Jun 9, 2023 | $2,000 | Freestanding Trellis; Firepit |
| 174249 | Addition (adds square footage) | Issued | Iss. Jun 9, 2023 |