251 Shoreline Hwy
Mill Valley 94941 · Tamalpais · Unincorporated Marin · Coordinates: 37.88171, -122.52512
Executive Verdict · Public-Records Synthesis
Zoned RMPC-6 in Unincorporated Marin with likely ministerial ADU eligibility and mapped FEMA AE flood due diligence; benchmark value $2,180,000 ($1,918,000–$2,442,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone RMPC-6 allows residential use qualifying for ministerial ADU review under state law (6 ADU permits permitted within ¼ mile in 36 months).
Source: Unincorporated Marin zoning · CA Gov. Code 66314
- ✓ 2 documented municipal building permits on file
On-parcel permit history is indexed through Sep 9, 2026, 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 Tamalpais
50 substantial renovation & housing permits over 24 months (20.5 per 1,000 parcels vs. 16.4 citywide baseline) (#3 of 22 neighborhoods).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (Tamalpais)
Watchouts & Due Diligence
- ! FEMA Special Flood Hazard Area (AE, all of the lot of lot)
Zone AE: 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)
- ! Delayed or open permit activity on this parcel
Electrical / panel (182526): Issued after 2 mo — slower than 90% of electrical / panel permits in Unincorporated Marin (median 0d, 90th pct 2d, n=3,019).
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 334 Dolan Ave (0.26 mi W, 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 (~$25,520/yr at $2,180,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,127/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:
- 11,805 sq ft (0.27 ac)
- Assessor use:
- Commercial - Improved
- Addresses on lot:
- 251 SHORELINE HWY
Zoning & Land Use
RMPC-6 — Residential Commercial Multiple Planned (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RMPC-6 (mixed use): state law allows ADUs where homes are allowed. On a multifamily lot the state allowance is different: ADUs in non-living space of the building, plus up to eight detached ADUs.
- SB 9: two homes on the lotUnlikely
Zoned RMPC-6 (mixed use), not a single-family residential zone.
- SB 9: split into two lotsUnlikely
Zoned RMPC-6 (mixed use), not a single-family residential zone.
Mapped Hazard Zones on This Lot
- CAL FIRE Fire Hazard Severity Zone
- Not in a State-mapped fire hazard severity zone
- FEMA National Flood Hazard Layer
- Zone AE: 1% annual chance flood (Special Flood Hazard Area) (all of the lot) · FIRM panel 06041C0469F, effective March 16, 2016
- CGS Alquist-Priolo Earthquake Fault Zone
- Not in an Alquist-Priolo Earthquake Fault Zone
Surrounding Rent & Value Benchmarks (Public Records)
Range: $1,918,000 – $2,442,000 · Status: Off market
HUD Small Area FMR (ZIP 94941) · FY 2026
Studio $2,730 · 1BR $3,270 · 2BR $3,960 · 3BR $5,060 · 4BR $5,240
Developments Deserving Closer Investigation & Active Area Builders
- Electrical / panel (182526) (Issued)On this parcel
Issued after 2 mo — slower than 90% of electrical / panel permits in Unincorporated Marin (median 0d, 90th pct 2d, n=3,019).
- New home at 334 Dolan Ave (Issued)0.26 mi W
Active in "Issued" for 8.2 yr (first record Sep 5, 2018) with no new permit activity recorded in 8 yr. High-impact scale (1 housing unit, $759,000 declared valuation across 1 permit).
- New home at 217 Cleveland Ave (Issued)0.29 mi NW
Active in "Issued" for 9.7 yr (first record Feb 21, 2017) with no new permit activity recorded in 2.3 yr. High-impact scale (1 housing unit, $875,000 declared valuation across 1 permit).
- Accessory dwelling unit at 131 Yale Ave A (Issued)0.48 mi NW
Active in "Issued" for 4.8 yr (first record Jan 19, 2022) with no new permit activity recorded in 3.4 yr. High-impact scale (1 housing unit, $1,000,000 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: Owner Builder (1 on parcel, 74 in ½ mi · Remodel / interior alteration); Cascade Roofing (1 on parcel, 1 in ½ mi · Roof replacement); Owner (46 in ½ mi · Remodel / interior alteration); Lek Enterprises (6 in ½ mi · Remodel / interior alteration); Lamperti Contracting And Design (4 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (2 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| 182526 | Electrical / panel | Issued | Iss. Sep 9, 2026 | $100 | Relocation Of One Gas Price Sign And Removal Of 2nd Gas Price Sign Per Code Enforcement And Planning Dept. (N) Sign Base… |
| 153799 | Roof replacement | Issued | Iss. Nov 9, 2016 | $10,000 | Reroof***Expired |