328 A Ridgewood Ave
Mill Valley 94941 · Homestead · Unincorporated Marin · Coordinates: 37.89464, -122.54593
Executive Verdict · Public-Records Synthesis
Zoned R1 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 $2,798,000 ($2,462,000–$3,134,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 15,638 sq ft lot. Local precedent is active with 4 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$508,200 contributory est.)
Public building records show issued construction/renovation work on this parcel (11 total permits, latest Apr 27, 2025).
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)
- ! Delayed or open permit activity on this parcel
Accessory dwelling unit at 328 Ridgewood Ave (adu 328a): Active in "Issued" for 2.4 yr (first record Jun 25, 2024) with no new permit activity recorded in 2 yr.
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (review-time benchmark)
- ! 3 slow or stalled nearby projects within ½ mile
Closest lead: New home (0.42 mi N, 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)
Parcel & Assessor
- Lot size:
- 15,638 sq ft (0.36 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 328A RIDGEWOOD AVE; 328 RIDGEWOOD AVE
Zoning & Land Use
R1 — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R1 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R1, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1, a single-family residential zone. The lot is 15,638 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: $2,462,000 – $3,134,000 · 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
- Accessory dwelling unit at 328 Ridgewood Ave (adu 328a) (Issued)On this parcel
Active in "Issued" for 2.4 yr (first record Jun 25, 2024) with no new permit activity recorded in 2 yr.
- New home (Entitled)0.42 mi N
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 (Entitled)0.44 mi N
In "Entitled" for 6.4 yr (since Jun 23, 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).
- General repair (84518) (Applied)On this parcel
Pending in review for 7 yr (31.0× the 83d median) — slower than 90% of general repair permits in Unincorporated Marin (median 83d, 90th pct 328d, n=693).
Entity-resolved builders & contractors in ½ mile: Owner Builder (1 on parcel, 56 in ½ mi · Remodel / interior alteration); Foley Built (6 on parcel, 7 in ½ mi · Addition (adds square footage)); American Solar (2 on parcel, 2 in ½ mi · Solar / battery storage); The Perfect Builder Dba Building Solutions (1 on parcel, 1 in ½ mi · New garage / accessory structure); Owner (26 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (11 permits, 2 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B42180 | Solar / battery storage | Issued | Iss. Apr 27, 2025 | $40,491 | 7.51kW Residential Roof-Mounted PV Array |
| 178300 | Addition (adds square footage) | Issued | Iss. Dec 11, 2024 | $500,000 | Addition; Deck - See 171010 |
| 177951 | General repair | Issued | Iss. Oct 25, 2024 | $50,000 | Upslope Retaining Walls |
| 177950 | General repair |