401 Headlands Ave
Mill Valley 94941 · Tamalpais · Unincorporated Marin · Coordinates: 37.87375, -122.52466
Executive Verdict · Public-Records Synthesis
Zoned RMP-0.5 in Unincorporated Marin with likely ministerial ADU eligibility and mapped CAL FIRE high fire hazard severity zone (state responsibility area) due diligence; benchmark value $2,202,000 ($1,938,000–$2,466,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone RMP-0.5 allows residential use qualifying for ministerial ADU review under state law.
Source: Unincorporated Marin zoning · CA Gov. Code 66314
- ✓ 4 documented municipal building permits on file
On-parcel permit history is indexed through Mar 18, 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
- ! 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)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: New home at 535 Tennessee Valley Rd (adu 531) (0.12 mi SW, 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 (~$25,773/yr at $2,202,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,148/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:
- 13,460 sq ft (0.31 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 401 HEADLANDS AVE
Zoning & Land Use
RMP-0.5 — Residential Multiple Planned (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RMP-0.5 (multifamily residential): 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 RMP-0.5 (multifamily residential), not a single-family residential zone.
- SB 9: split into two lotsUnlikely
Zoned RMP-0.5 (multifamily residential), not a single-family residential zone.
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 06041C0507E, 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: $1,938,000 – $2,466,000 · 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 535 Tennessee Valley Rd (adu 531) (Issued)0.12 mi SW
Active in "Issued" for 6 yr (first record Oct 29, 2020) with no new permit activity recorded in 4 yr. High-impact scale (1 housing unit, $800,000 declared valuation across 1 permit).
- New home at 25 Burgess Ct (adu #23) (Issued)0.5 mi E
Active in "Issued" for 6.9 yr (first record Dec 30, 2019) with no new permit activity recorded in 5.1 yr. High-impact scale (1 housing unit, $2,200,000 declared valuation across 1 permit).
- Demolition at 531 Tennessee Valley Rd (Issued)0.11 mi SW
Active in "Issued" for 5.1 yr (first record Oct 7, 2021) with no new permit activity recorded in 4.8 yr.
- New commercial building at 203 Marin Ave (Applied)0.2 mi NW
Active in "Applied" for 9.6 yr (first record Mar 20, 2017) with no new permit activity recorded in 9.6 yr.
Entity-resolved builders & contractors in ½ mile: Peter Levi Plumbing (2 on parcel, 2 in ½ mi · HVAC / heat pump); R And R Roofing (1 on parcel, 1 in ½ mi · Roof replacement); Renewal By Andersen (1 on parcel, 1 in ½ mi · Windows / doors / siding); Owner Builder (35 in ½ mi · Remodel / interior alteration); Owner (28 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (4 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B46220 | Roof replacement | Issued | Iss. Mar 18, 2026 | $30,000 | ReRoofing; With Electronic Inspection |
| B37458 | HVAC / heat pump | Issued | Iss. Mar 25, 2024 | $14,000 | Remove and replace ductwork located in crawlspace, like for like — Replace Ductwork |
| B14621 | HVAC / heat pump | Issued | Iss. Mar 29, 2018 | $7,000 | Change out furnace — Replace Mechanical Appliance |
| 156758 | Windows / doors / siding | Issued | Iss. Oct 16, 2017 | $14,003 | Replace 1 Patio Door In Same Location, Sasme Size |