36 Plaza Dr
Mill Valley 94941 · Alto · Unincorporated Marin · Coordinates: 37.90537, -122.51671
Executive Verdict · Public-Records Synthesis
Zoned R1-B1 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and zero mapped flood, fire, or fault hazard overlaps; benchmark value $2,111,000 ($1,858,000–$2,364,000).
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 7,579 sq ft lot. Local precedent is active with 8 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ 4 documented municipal building permits on file
On-parcel permit history is indexed through Jun 2, 2020, 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)
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)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: New home at 55 Thomas Dr (0.25 mi E, 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 (~$24,727/yr at $2,111,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,061/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:
- 7,579 sq ft (0.17 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 36 PLAZA DR
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 7,579 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
- Not in a State-mapped fire hazard severity zone
- FEMA National Flood Hazard Layer
- Zone X: minimal flood hazard (all of the lot) · FIRM panel 06041C0469F, 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: $1,858,000 – $2,364,000 · 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 55 Thomas Dr (Applied)0.25 mi E
In "Applied" for 6.2 yr (since Sep 1, 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, $1,000,000 declared valuation across 1 permit).
- Accessory dwelling unit at 55 Plaza Dr (adu 55a) (Issued)510 ft SW
Active in "Issued" for 2.6 yr (first record Apr 17, 2024) with no new permit activity recorded in 19 mo. High-impact scale (1 housing unit, $790,000 declared valuation across 1 permit).
- New home at 30 Shell Rd (Issued)0.13 mi NW
Active in "Issued" for 2.4 yr (first record Jul 5, 2024) with no new permit activity recorded in 22 mo. High-impact scale (1 housing unit, $2,800,000 declared valuation across 1 permit).
- New home at 55 S Knoll Rd (Issued)0.43 mi SE
Active in "Issued" for 11.9 yr (first record Dec 22, 2014) with no new permit activity recorded in 11.4 yr. High-impact scale (1 housing unit, $750,000 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: Owner Builder (1 on parcel, 38 in ½ mi · Remodel / interior alteration); Red Point Builders (2 on parcel, 2 in ½ mi · New garage / accessory structure); Saw Designs (1 on parcel, 1 in ½ mi · HVAC / heat pump); Owner (24 in ½ mi · Remodel / interior alteration); Drosihn Construction (7 in ½ mi · New single-family home).
Permit & Project History on This Parcel (4 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B22689 | HVAC / heat pump | Issued | Iss. Jun 2, 2020 | $5,000 | Install Air Conditioning to existing furnace and ducts — New Circuits / Outlets; New Plumbing Fixture(s); Mechanical App… |
| 149757 | New garage / accessory structure | Issued | Iss. Nov 10, 2015 | $80,000 | Garage |
| 149753 | New garage / accessory structure | Issued | Iss. Nov 10, 2015 | $260,000 | Addition To Main Floor(Rebuilt) And New 2nd Floor, Deck T.D. 3/11/15 |
| 147270 | Demolition | Issued | Iss. May 26, 2015 | $5,000 | Demo Garage - See 72895 & 73580 |