20 Summer St
Dillon Beach 94929 · Dillon Beach · Unincorporated Marin · Coordinates: 38.25105, -122.96588
Executive Verdict · Public-Records Synthesis
Zoned C-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 $1,396,000 ($1,228,000–$1,564,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned C-R1-BD supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 4,922 sq ft lot.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ 1 documented municipal building permit on file
On-parcel permit history is indexed through Feb 28, 2019, 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)
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 40 Sea Bluff (0.15 mi S, 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 (~$16,504/yr at $1,396,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$1,375/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:
- 4,922 sq ft (0.11 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 20 SUMMER ST
Zoning & Land Use
C-R1-BD — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned C-R1-BD (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned C-R1-BD, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned C-R1-BD, a single-family residential zone. The lot is 4,922 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 06041C0040E, 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: $1,228,000 – $1,564,000 · Status: Off market
HUD Small Area FMR (ZIP 94929) · FY 2026
Studio $2,050 · 1BR $2,510 · 2BR $2,990 · 3BR $4,010 · 4BR $4,280
Developments Deserving Closer Investigation & Active Area Builders
- New home at 40 Sea Bluff (Issued)0.15 mi S
Active in "Issued" for 3.4 yr (first record Jun 2, 2023) with no new permit activity recorded in 3.1 yr. High-impact scale (1 housing unit, $1,600,000 declared valuation across 1 permit).
- New home at 20 Sea Bluff (Issued)0.15 mi S
Active in "Issued" for 3.5 yr (first record May 16, 2023) with no new permit activity recorded in 3.2 yr. High-impact scale (1 housing unit, $1,420,000 declared valuation across 1 permit).
- New home at 314 Oceana Dr (Issued)0.22 mi N
Active in "Issued" for 3.4 yr (first record Jun 6, 2023) with no new permit activity recorded in 2.1 yr. High-impact scale (1 housing unit, $1,783,932 declared valuation across 1 permit).
- New home at 429 Oceana Dr (Issued)0.32 mi NE
Active in "Issued" for 4 yr (first record Nov 29, 2022) with no new permit activity recorded in 2.3 yr. High-impact scale (1 housing unit, $1,000,000 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: David Penny Construction Services (1 on parcel, 1 in ½ mi · Windows / doors / siding); Owner Builder (19 in ½ mi · Remodel / interior alteration); Owner (9 in ½ mi · New garage / accessory structure); Roseberry Construction (5 in ½ mi · New garage / accessory structure); Carreiro Tom Const (2 in ½ mi · New garage / accessory structure).
Permit & Project History on This Parcel (1 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| 160868 | Windows / doors / siding | Issued | Iss. Feb 28, 2019 | $2,000 | Wndw Install.***Bwop T.D. 2/27/19 |