506 Browning St
Mill Valley 94941 · Tamalpais · Unincorporated Marin · Coordinates: 37.88075, -122.53863
Executive Verdict · Public-Records Synthesis
Zoned R2 in Unincorporated Marin with likely ministerial ADU eligibility and mapped CAL FIRE moderate fire hazard severity zone (state responsibility area) due diligence; benchmark value $1,887,000 ($1,661,000–$2,113,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone R2 allows residential use qualifying for ministerial ADU review under state law (5 ADU permits permitted within ¼ mile in 36 months).
Source: Unincorporated Marin zoning · CA Gov. Code 66314
- ✓ 4 documented municipal building permits on file
On-parcel permit history is indexed through May 24, 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)
- ✓ 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 Moderate 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 560 Alta Way (0.35 mi N, 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 (~$22,151/yr at $1,887,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$1,846/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:
- 1,307 sq ft (0.03 ac)
- Assessor use:
- Single Family Attached
- Addresses on lot:
- 506 BROWNING ST
Zoning & Land Use
R2 — Residential Two Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R2 (two-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotCan't tell
Zoned R2 (two-family residential): we can't tell whether it counts as a single-family zone for SB 9. Residential Two Family.
- SB 9: split into two lotsCan't tell
Zoned R2 (two-family residential): we can't tell whether it counts as a single-family zone for SB 9. Residential Two Family.
Mapped Hazard Zones on This Lot
- CAL FIRE Fire Hazard Severity Zone
- Moderate 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 06041C0468F, 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: $1,661,000 – $2,113,000 · 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 560 Alta Way (Applied)0.35 mi N
In "Applied" for 3.3 yr (since Aug 10, 2023), 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, $975,000 declared valuation across 1 permit).
- New home at 731 Bay Rd (Issued)0.18 mi SW
Active in "Issued" for 18 mo (first record May 12, 2025) with no new permit activity recorded in 15 mo. High-impact scale (1 housing unit, $955,000 declared valuation across 1 permit).
- Accessory dwelling unit at 403 Marin Ave (adu 403a) (Issued)0.25 mi SE
Active in "Issued" for 2.9 yr (first record Dec 21, 2023) with no new permit activity recorded in 19 mo. High-impact scale (1 housing unit, $1,000,000 declared valuation across 1 permit).
- New home at 469 W Live Oak Dr (aka 461) (Issued)0.31 mi S
Active in "Issued" for 6.1 yr (first record Oct 22, 2020) with no new permit activity recorded in 22 mo. High-impact scale (1 housing unit, $980,000 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: Owner (1 on parcel, 44 in ½ mi · Remodel / interior alteration); Renewal By Andersen (1 on parcel, 1 in ½ mi · Windows / doors / siding); Peter Levi Plumbing (1 on parcel, 1 in ½ mi · Plumbing / water heater / sewer); Gagne Brothers Enterprises (1 on parcel, 1 in ½ mi · Plumbing / water heater / sewer); Owner Builder (95 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (4 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B42521 | EV charger | Issued | Iss. May 24, 2025 | $4,000 | We would like to add an electrical line with a outdoor power outlet and an independent EV 50 amp charger with smart mete… |
| B36210 | Plumbing / water heater / sewer | Issued | Iss. Nov 22, 2023 | $6,500 | swap out existing tankless on exterior wall for Navien 180A tankless NG WH model #: NPE-180A2 — Replace Plumbing Fixture… |
| B36199 | Plumbing / water heater / sewer | Issued | Iss. Nov 21, 2023 | $5,300 | REPLACE TANKLESS WATER HEATER WITH 180K BTUS LIKE FOR LIKE — Replace Plumbing Fixtures(s) |
| 161043 | Windows / doors / siding | Issued | Iss. Mar 19, 2019 | $33,487 | 6 Windows Like For Like. 1 Pre-Fab Bay Window Same Header. T.D. 3/7/19 |