80 Mountain Ln
Mill Valley 94941 · Muir Woods Park · Unincorporated Marin · Coordinates: 37.90515, -122.56826
Executive Verdict · Public-Records Synthesis
Zoned R1-B2 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and mapped CAL FIRE high fire hazard severity zone (state responsibility area) due diligence; benchmark value $2,138,000 ($1,881,000–$2,395,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1-B2 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 8,320 sq ft lot.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$33,000 contributory est.)
Public building records show issued construction/renovation work on this parcel (5 total permits, latest Apr 30, 2026).
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 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)
- ! 5 slow or stalled nearby projects within ½ mile
Closest lead: New home at 526 Panoramic Hwy (0.23 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 (~$25,037/yr at $2,138,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,086/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:
- 8,320 sq ft (0.19 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 80 MOUNTAIN LN
Zoning & Land Use
R1-B2 — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R1-B2 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R1-B2, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1-B2, a single-family residential zone. The lot is 8,320 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
- High 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 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: $1,881,000 – $2,395,000 · 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 526 Panoramic Hwy (Issued)0.23 mi S
Active in "Issued" for 4.6 yr (first record Apr 21, 2022) with no new permit activity recorded in 2 yr. High-impact scale (1 housing unit, $1,329,450 declared valuation across 2 permits).
- New home at 120 Redwood Ave (Issued)0.15 mi S
Active in "Issued" for 14.9 yr (first record Dec 27, 2011) with no new permit activity recorded in 11.9 yr.
- Demolition at 7 Brighton Blvd (Issued)0.36 mi SE
Active in "Issued" for 11.8 yr (first record Jan 13, 2015) with no new permit activity recorded in 11.8 yr.
- New home (Issued)0.46 mi N
Active in "Issued" for 7.1 yr (first record Sep 30, 2019) with no new permit activity recorded in 7.1 yr.
Entity-resolved builders & contractors in ½ mile: Canseco Construction (1 on parcel, 1 in ½ mi · Remodel / interior alteration); Apollo Building And Roofing Group (1 on parcel, 1 in ½ mi · Roof replacement); Rock Solid Electrical (1 on parcel, 1 in ½ mi · Electrical / panel); Bonney (1 on parcel, 1 in ½ mi · Plumbing / water heater / sewer); Groundworks California (1 on parcel, 1 in ½ mi · General repair).
Permit & Project History on This Parcel (5 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| 181601 | Remodel / interior alteration | Issued | Iss. Apr 30, 2026 | $60,000 | Remodel 2 Bathrooms, Laundry |
| 178157 | General repair | Issued | Iss. Nov 20, 2024 | $6,887 | Floor Leveling Using 4x8 Dfl #2 Supplemental Beam |
| B39443 | Roof replacement | Issued | Iss. Sep 10, 2024 | $25,000 | re-roof 26SQ install TPO — ReRoofing |
| B38306 | Electrical / panel | Issued | Iss. Jun 6, 2024 | $7,500 | Like for like replacement of 1 125 amp zinsco and 1 125 amp federal pacific electrical subpanels. — Replace Circuits / O… |
| B24120 | Plumbing / water heater / sewer | Issued | Iss. Nov 9, 2020 |