532 Alta Way
Mill Valley 94941 · Tamalpais · Unincorporated Marin · Coordinates: 37.88647, -122.54005
Executive Verdict · Public-Records Synthesis
Zoned R1-B1 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and mapped CAL FIRE moderate fire hazard severity zone (state responsibility area) due diligence; benchmark value $2,090,000 ($1,839,000–$2,341,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1-B1 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 6,186 sq ft lot. Local precedent is active with 7 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$16,706 contributory est.)
Public building records show issued construction/renovation work on this parcel (4 total permits, latest Mar 20, 2024).
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 (390 ft SW, 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 (~$24,485/yr at $2,090,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,040/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:
- 6,186 sq ft (0.14 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 532 ALTA WAY
Zoning & Land Use
R1-B1 — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R1-B1 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R1-B1, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1-B1, a single-family residential zone. The lot is 6,186 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
- 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: $1,839,000 – $2,341,000 · 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
Nearby Activity (½ mile radius, since November 2024)
16 active or recent development projects (15 housing units across completed, permitted, and pipeline stages) and 540 total building permits recorded within ½ mile.
- New construction4 permits (1 units)
- Adds housing (ADU)13 permits (13 units)
- Demolition1 permit
- Additions & renovations36 permits
- Building systems380 permits
- Repairs17 permits
- Other89 permits
Developments Deserving Closer Investigation & Active Area Builders
- New home at 560 Alta Way (Applied)390 ft SW
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 commercial building at 100 Harvard Ave (Issued)0.41 mi E
Active in "Issued" for 23 mo (first record Dec 26, 2024) with no new permit activity recorded in 18 mo. High-impact scale ($6,500,000 declared valuation across 1 permit).
- New home at 210 Brabo Ter (Issued)0.46 mi N
Active in "Issued" for 3.1 yr (first record Oct 12, 2023) with no new permit activity recorded in 2.6 yr. High-impact scale (1 housing unit, $850,000 declared valuation across 1 permit).
- New home at 204 Reed St (Issued)0.49 mi N
Active in "Issued" for 4.3 yr (first record Aug 5, 2022) with no new permit activity recorded in 3.5 yr. High-impact scale (1 housing unit, $950,000 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: Jta Construction (1 on parcel, 1 in ½ mi · Remodel / interior alteration); Peter Levi Plumbing (1 on parcel, 1 in ½ mi · HVAC / heat pump); Marin H20 (1 on parcel, 1 in ½ mi · Plumbing / water heater / sewer); Owner Builder (81 in ½ mi · Remodel / interior alteration); Owner (39 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (4 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B37396 | HVAC / heat pump | Issued | Iss. Mar 20, 2024 | $9,000 | Remove and replace Furnace, like for like. Carrier Furnace Model #: 58TP1B090V17--16 — Replace Mechanical Appliance |
| 172763 | Remodel / interior alteration | Issued | Iss. Nov 16, 2022 | $23,000 | Master Bath Remodel - Express |
| B25864 | Plumbing / water heater / sewer | Issued | Iss. May 26, 2021 | $2,250 | RE-LOCATE GAS METER FROM CURRENT LOCATION, 4 FEET FORWARD TO THE RIGHT FRONT CORNER OF THER HOUSE. NEW LOCATION IS PRE-A… |
| 166242 | Solar / battery storage | Issued | Iss. Nov 12, 2020 | $13,040 | Photovoltaic 4.08kw & Energy Storage System |