20 Calle Del Sierra
Stinson Beach 94970 · Stinson Beach · Unincorporated Marin · Coordinates: 37.89924, -122.64441
Executive Verdict · Public-Records Synthesis
Zoned C-R2 in Unincorporated Marin and mapped FEMA AO flood / CAL FIRE very high fire hazard severity zone (local responsibility area) due diligence; benchmark value $2,774,000 ($2,441,000–$3,107,000).
Upsides & Opportunities
- ✓ Documented permitted upgrades (+$45,144 contributory est.)
Public building records show issued construction/renovation work on this parcel (2 total permits, latest May 8, 2019).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
Watchouts & Due Diligence
- ! FEMA Special Flood Hazard Area (AO, all of the lot of lot)
Zone AO: 1% annual chance flood (Special Flood Hazard Area) overlaps this parcel. Expect mandatory flood insurance for federally backed loans and floodplain elevation/mitigation rules for new units or SB 9 applications.
Source: FEMA National Flood Hazard Layer (parcel polygon)
- ! CAL FIRE Very High Fire Hazard Severity Zone (Local 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 Mar 24, 2025)
- ! Delayed or open permit activity on this parcel
Remodel / interior alteration (161467): Issued after 9 mo (3.5× 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)
- ! 4 slow or stalled nearby projects within ½ mile
Closest lead: New home at 25 Lincoln Ave (0.25 mi E, 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:
- 2,352 sq ft (0.05 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 20 CALLE DEL SIERRA
Zoning & Land Use
C-R2 — Residential Two Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADUPossible, with conditions
Zoned C-R2 (two-family residential): state law allows ADUs where homes are allowed. Very High Fire Hazard Severity Zone covers all of the lot: cities may limit ADUs here for fire safety and evacuation.
- SB 9: two homes on the lotCan't tell
Zoned C-R2 (two-family residential): we can't tell whether it counts as a single-family zone for SB 9. Residential Two Family.
- SB 9: split into two lotsCan't tell
Zoned C-R2 (two-family residential): we can't tell whether it counts as a single-family zone for SB 9. Residential Two Family.
Mapped Hazard Zones on This Lot
- CAL FIRE Fire Hazard Severity Zone
- Very High Fire Hazard Severity Zone (Local Responsibility Area) (all of the lot, map Mar 24, 2025)
- FEMA National Flood Hazard Layer
- Zone AO: 1% annual chance flood (Special Flood Hazard Area) (all of the lot) · FIRM panel 06041C0444E, effective August 15, 2017
- CGS Alquist-Priolo Earthquake Fault Zone
- Not in an Alquist-Priolo Earthquake Fault Zone
Surrounding Rent & Value Benchmarks (Public Records)
Range: $2,441,000 – $3,107,000 · Status: Off market
HUD Small Area FMR (ZIP 94970) · FY 2026
Studio $2,090 · 1BR $2,510 · 2BR $3,030 · 3BR $3,870 · 4BR $4,010
Developments Deserving Closer Investigation & Active Area Builders
- Remodel / interior alteration (161467) (Issued)On this parcel
Issued after 9 mo (3.5× the 83d median) — slower than 90% of remodel / interior alteration permits in Unincorporated Marin (median 83d, 90th pct 266d, n=1,054).
- HVAC / heat pump (157652) (Issued)On this parcel
Issued after 4 mo — slower than 90% of hvac / heat pump permits in Unincorporated Marin (median 0d, 90th pct 0d, n=2,946).
- New home at 25 Lincoln Ave (Issued)0.25 mi E
Active in "Issued" for 7.3 yr (first record Jul 22, 2019) with no new permit activity recorded in 7.1 yr. High-impact scale (1 housing unit, $969,000 declared valuation across 1 permit).
- Mixed-use development at 3466 State Route 1 & (Issued)0.3 mi E
Active in "Issued" for 6.1 yr (first record Sep 23, 2020) with no new permit activity recorded in 5.1 yr. High-impact scale (1 housing unit, $1,000,000 declared valuation across 2 permits).
Entity-resolved builders & contractors in ½ mile: Tim Trumbo (1 on parcel, 4 in ½ mi · Addition (adds square footage)); Owner Builder (17 in ½ mi · Commercial tenant improvement); Owner (9 in ½ mi · New garage / accessory structure); Gubbins Building (6 in ½ mi · New garage / accessory structure); George T Flynn Construction (4 in ½ mi · New garage / accessory structure).
Permit & Project History on This Parcel (2 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| 161467 | Remodel / interior alteration | Issued | Iss. May 8, 2019 | $114,000 | Struc Roof, Insulate, Wndws/Door, Siding T.D. 1/9/2019 |
| 157652 | HVAC / heat pump | Issued | Iss. Feb 8, 2018 | $40,000 | Voluntary Raise Found; Struct Wndws; Mech; Plumbing T.D. 11/17/17 |