5 Ridge Ave
Mill Valley 94941 · Muir Woods Park · Unincorporated Marin · Coordinates: 37.89980, -122.56701
Executive Verdict · Public-Records Synthesis
Zoned R1-B3 in Unincorporated Marin and mapped CAL FIRE very high fire hazard severity zone (state responsibility area) due diligence; benchmark value $2,299,000 ($2,023,000–$2,575,000).
Upsides & Opportunities
- ✓ Documented permitted upgrades (+$17,127 contributory est.)
Public building records show issued construction/renovation work on this parcel (4 total permits, latest Nov 4, 2026).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
Watchouts & Due Diligence
- ! Mapped flood awareness zone (Zone D: possible but undetermined flood hazard)
all of the lot of the parcel intersects Zone D: possible but undetermined 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 Very High 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 65 Ridge Ave (0.22 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)
- ! Year 1 Prop 13 tax reset (~$26,889/yr at $2,299,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,241/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:
- 24,481 sq ft (0.56 ac)
- Assessor use:
- Multiple-Resid. - Improved
- Addresses on lot:
- 5 RIDGE AVE
Zoning & Land Use
R1-B3 — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADUPossible, with conditions
Zoned R1-B3 (single-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 lotPossible, with conditions
Zoned R1-B3, a single-family residential zone. Very High Fire Hazard Severity Zone (State responsibility area) covers all of the lot: SB 9 requires the project to meet the fire hazard mitigation standards.
- SB 9: split into two lotsPossible, with conditions
Zoned R1-B3, a single-family residential zone. The lot is 24,481 sq ft by the assessor, room for two lots of at least 1,200 sq ft, each at least 40% of the original. Very High Fire Hazard Severity Zone (State responsibility area) covers all of the lot: SB 9 requires the project to meet the fire hazard mitigation standards.
Mapped Hazard Zones on This Lot
- CAL FIRE Fire Hazard Severity Zone
- Very High Fire Hazard Severity Zone (State Responsibility Area) (all of the lot, map Apr 1, 2024)
- FEMA National Flood Hazard Layer
- Zone D: possible but undetermined flood hazard (all of the lot) · FIRM panel 06041C0465E, 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: $2,023,000 – $2,575,000 · 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
- New home at 65 Ridge Ave (Applied)0.22 mi SE
In "Applied" for 4 yr (since Oct 27, 2022), 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, $3,000,000 declared valuation across 1 permit).
- New home at 526 Panoramic Hwy (Issued)0.15 mi NW
Active in "Issued" for 4.6 yr (first record Apr 21, 2022) with no new permit activity recorded in 2.1 yr. High-impact scale (1 housing unit, $1,329,450 declared valuation across 2 permits).
- New home at 49 Ridge Ave (Applied)0.13 mi S
In "Applied" for 5.1 yr (since Oct 15, 2021), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
- Demolition at 688 Sequoia Valley Rd (Applied)0.47 mi E
In "Applied" for 3.2 yr (since Sep 6, 2023), exceeding the 55d median and 261d 90th percentile for demolition permits in Unincorporated Marin (n=130).
Entity-resolved builders & contractors in ½ mile: Ernest Ongaro And Sons (2 on parcel, 2 in ½ mi · Other); Vital Energy Solutions (1 on parcel, 1 in ½ mi · Solar / battery storage); Moore Services (1 on parcel, 1 in ½ mi · HVAC / heat pump); Owner Builder (28 in ½ mi · Remodel / interior alteration); Owner (9 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (4 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B49007 | Other | Issued | Iss. Nov 4, 2026 | $10,000 | Mechanical Appliance, Replace Mechanical Appliance |
| B47367 | Plumbing / water heater / sewer | Issued | Iss. Jul 1, 2026 | $9,239 | Replace Plumbing Fixtures(s) |
| B44265 | Solar / battery storage | Issued | Iss. Oct 8, 2025 | $39,645 | Roof-mount PV 4.60kW DC, and ESS 10.4kWh. |
| B24512 | HVAC / heat pump | Issued | Iss. Dec 29, 2020 | $3,500 | CHANGE OUT SINGLE ZONE (1 TON) MINI SPLIT SYSTEM ON LEFT SIDE OF YARD — Replace Mechanical Appliance |