522 Tamalpais Dr
Mill Valley 94941 · Homestead · Unincorporated Marin · Coordinates: 37.89988, -122.55571
Executive Verdict · Public-Records Synthesis
Zoned RSP-7 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 $2,637,000 ($2,321,000–$2,953,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned RSP-7 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 24,829 sq ft lot. Local precedent is active with 1 ADU permit within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$268,200 contributory est.)
Public building records show issued construction/renovation work on this parcel (4 total permits, latest Apr 21, 2021).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
- ✓ Above-average reinvestment in Homestead
22 substantial renovation & housing permits over 24 months (20.7 per 1,000 parcels vs. 16.4 citywide baseline) (#2 of 22 neighborhoods).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (Homestead)
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 (0.4 mi E, entitled). 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 (~$30,776/yr at $2,637,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,565/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:
- 24,829 sq ft (0.57 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 522 TAMALPAIS DR; 524 TAMALPAIS DR
Zoning & Land Use
RSP-7 — Residential Single Family Planned (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RSP-7 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned RSP-7, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned RSP-7, a single-family residential zone. The lot is 24,829 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 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: $2,321,000 – $2,953,000 · 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 (Entitled)0.4 mi E
In "Entitled" for 6.3 yr (since Aug 11, 2020), 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, 1 deed-restricted affordable across 0 permits).
- New home at 420 Laverne Ave (Issued)0.37 mi SE
Active in "Issued" for 8.6 yr (first record Apr 23, 2018) with no new permit activity recorded in 3.8 yr. High-impact scale (1 housing unit, $1,100,000 declared valuation across 1 permit).
- New home at 2 Hart Ln (Issued)0.38 mi E
Active in "Issued" for 6.9 yr (first record Dec 18, 2019) with no new permit activity recorded in 5.9 yr. High-impact scale (1 housing unit, $750,000 declared valuation across 1 permit).
- Accessory dwelling unit at 408 Laverne Ave (adu 408a) (Issued)0.4 mi SE
Active in "Issued" for 2.3 yr (first record Jul 12, 2024) with no new permit activity recorded in 14 mo. High-impact scale (1 housing unit, $2,700,000 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: Owner (1 on parcel, 13 in ½ mi · Remodel / interior alteration); Manuel Ricardo Zapata (1 on parcel, 1 in ½ mi · HVAC / heat pump); Elex Solutions (1 on parcel, 1 in ½ mi · Electrical / panel); Owner Builder (29 in ½ mi · Remodel / interior alteration); Green Bay Remodeling (3 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (4 permits, 1 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B25527 | HVAC / heat pump | Issued | Iss. Apr 21, 2021 | $8,500 | Furnace Replacement 95%AFUE AC Add on 14 SEER Install a 20 amp breaker partial duct replacement — Replace Ductwork, Mech… |
| 163027 | Accessory dwelling unit (new or conversion) | Issued | Iss. Oct 24, 2019 | $150,000 | Adu T.D. 7/31/19 |
| 163026 | Addition (adds square footage) | Issued | Iss. Oct 24, 2019 | $150,000 | Ktch Rmdl, Addtn & Retaining Wall T.D. 7/31/19 |
| B13312 | Electrical / panel | Issued | Iss. Sep 19, 2017 | $1,200 |