122 Mountain Ln
Mill Valley 94941 · Muir Woods Park · Unincorporated Marin · Coordinates: 37.90595, -122.56859
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 $1,901,000 ($1,673,000–$2,129,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1-B2 supports ministerial ADU/JADU review plus SB 9 two-unit residential development on a 2,396 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 Jun 16, 2025, 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 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 (0.29 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 (~$22,312/yr at $1,901,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$1,859/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:
- 2,396 sq ft (0.06 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 122 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 lotsUnlikely
Zoned R1-B2, a single-family residential zone. The lot is 2,396 sq ft by the assessor; a split needs at least 2,400 sq ft (two lots of 1,200 sq ft or more).
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: $1,673,000 – $2,129,000 · 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)0.29 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)0.21 mi S
Active in "Issued" for 14.9 yr (first record Dec 27, 2011) with no new permit activity recorded in 11.9 yr.
- New home (Issued)0.41 mi N
Active in "Issued" for 7.1 yr (first record Sep 30, 2019) with no new permit activity recorded in 7.1 yr.
- Demolition at 7 Brighton Blvd (Issued)0.42 mi SE
Active in "Issued" for 11.8 yr (first record Jan 13, 2015) with no new permit activity recorded in 11.8 yr.
Entity-resolved builders & contractors in ½ mile: Arb (1 on parcel, 1 in ½ mi · Plumbing / water heater / sewer); Owner Builder (21 in ½ mi · New garage / accessory structure); Owner (9 in ½ mi · Remodel / interior alteration); Vida Building (2 in ½ mi · Remodel / interior alteration); Oxbow Pool And Landscape Contractors (1 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 |
|---|---|---|---|---|---|
| B42769 | Plumbing / water heater / sewer | Issued | Iss. Jun 16, 2025 | $3,500 | Extending houseline gas plumbing to facilitate meter move — New Gas Service |