860 Butterfield Ln
San Anselmo 94960 · Sleepy Hollow · Unincorporated Marin · Coordinates: 38.00391, -122.57350
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 $2,173,000 ($1,912,000–$2,434,000).
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 25,831 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 (+$175,980 contributory est.)
Public building records show issued construction/renovation work on this parcel (6 total permits, latest Feb 9, 2026).
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
Remodel / interior alteration (166530): Pending in review for 6 yr (26.3× the 83d median) — slower than 90% of remodel / interior alteration permits in Unincorporated Marin (median 83d, 90th pct 266d, n=1,054).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (review-time benchmark)
- ! 5 slow or stalled nearby projects within ½ mile
Closest lead: New home at 666 Fawn Dr (0.41 mi SE, 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:
- 25,831 sq ft (0.59 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 860 BUTTERFIELD LN
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 25,831 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: $1,912,000 – $2,434,000 · 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 666 Fawn Dr (Applied)0.41 mi SE
In "Applied" for 7.5 yr (since Apr 29, 2019), 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, $1,000,000 declared valuation across 1 permit).
- Remodel / interior alteration (166530) (Applied)On this parcel
Pending in review for 6 yr (26.3× 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)370 ft SW
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).
- Demolition at 854 Butterfield Ln (Applied)190 ft SW
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: Owner Builder (2 on parcel, 29 in ½ mi · Remodel / interior alteration); Level House Construction (2 on parcel, 2 in ½ mi · Addition (adds square footage)); Solarcraft Services (1 on parcel, 1 in ½ mi · Solar / battery storage); Tamura Construction Services (1 on parcel, 1 in ½ mi · Other); Owner (11 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (6 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B45804 | Other | Issued | Iss. Feb 9, 2026 | $15,000 | — |
| B43428 | Solar / battery storage | Issued | Iss. Aug 12, 2025 | $47,000 | NEW FLUSH MOUNTED PV SYSTEM WITH NEW BATTERY STORAGE, GRID TIED HYBRID INVERTERS, TO MAIN SERVICE PANEL. |
| 166530 | Remodel / interior alteration | Applied | App. Nov 24, 2020 | $10,000 | Struct. Inter. Remdl: N/Bdrm, Closet, & Den |
| 165581 | Addition (adds square footage) | Issued | Iss. Sep 1, 2020 | $250,000 | Addtn, Rmdl Kitch, Mstr Bth, Vault Lvg Rm Clg, Add Skylight T.D. 6/23/20 |
| 161766 | Demolition | Issued | Iss. Jun 10, 2019 |