231 Princeton Ave
Mill Valley 94941 · Almonte · Unincorporated Marin · Coordinates: 37.88562, -122.52883
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 $2,455,000 ($2,160,000–$2,750,000).
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 30,928 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 (+$138,000 contributory est.)
Public building records show issued construction/renovation work on this parcel (7 total permits, latest Nov 4, 2024).
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)
- ! Delayed or open permit activity on this parcel
Remodel / interior alteration (90992): Pending in review for 3.6 yr (15.9× the 83d median) — slower than 90% of remodel / interior alteration permits in Unincorporated Marin (median 83d, 90th pct 266d, n=1,054).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (review-time benchmark)
- ! 4 slow or stalled nearby projects within ½ mile
Closest lead: New home at 217 Cleveland Ave (260 ft SE, issued). 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 (~$28,683/yr at $2,455,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,390/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:
- 30,928 sq ft (0.71 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 231 PRINCETON AVE
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 30,928 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: $2,160,000 – $2,750,000 · 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
- Remodel / interior alteration (90992) (Applied)On this parcel
Pending in review for 3.6 yr (15.9× the 83d median) — slower than 90% of remodel / interior alteration permits in Unincorporated Marin (median 83d, 90th pct 266d, n=1,054).
- Windows / doors / siding (161031) (Issued)On this parcel
Issued after 17 mo — slower than 90% of windows / doors / siding permits in Unincorporated Marin (median 0d, 90th pct 5d, n=1,476).
- New home at 217 Cleveland Ave (Issued)260 ft SE
Active in "Issued" for 9.7 yr (first record Feb 21, 2017) with no new permit activity recorded in 2.3 yr. High-impact scale (1 housing unit, $875,000 declared valuation across 1 permit).
- Accessory dwelling unit at 131 Yale Ave A (Issued)0.16 mi N
Active in "Issued" for 4.8 yr (first record Jan 19, 2022) with no new permit activity recorded in 3.4 yr. High-impact scale (1 housing unit, $1,000,000 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: Ignacio Camarillo Reyes (2 on parcel, 2 in ½ mi · Remodel / interior alteration); Lonnie The Electrician (2 on parcel, 2 in ½ mi · Electrical / panel); Fritz Bldg (1 on parcel, 1 in ½ mi · Windows / doors / siding); Solar Optimum (1 on parcel, 1 in ½ mi · Roof replacement); Owner Builder (92 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (7 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| 178014 | Remodel / interior alteration | Issued | Iss. Nov 4, 2024 | $400,000 | Remodel: Kitchen, Guest Bath & Primary Bath, Living Rm Fireplace Insert Replacement, (N) Windows & Doors, Kitchenette, L… |
| B38732 | Windows / doors / siding | Issued | Iss. Jul 15, 2024 | $12,500 | Replace Front Door, Breakfast Nook Side Door & 3 windows within existing openings. No structural work. — Non-structural … |
| 90992 | Remodel / interior alteration | Applied | App. Apr 6, 2023 | $375,000 | Remodel Kitchen, Bathroom, & Closet; Replace (E) Fireplace, Replace (E) Windows |
| B27914 | Roof replacement | Issued | Iss. Nov 29, 2021 | $25,000 | Installation of a 7.03 kW Roof-Mounted (19) Modules, (19) Micro-Inverters, (1) Tesla Powerwall, (1) 200A Tesla Gateway, … |
| 161031 |