266 Princeton Ave
Mill Valley 94941 · Almonte · Unincorporated Marin · Coordinates: 37.88430, -122.52997
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 $2,200,000 ($1,936,000–$2,464,000).
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 11,021 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
- ✓ Documented permitted upgrades (+$18,810 contributory est.)
Public building records show issued construction/renovation work on this parcel (8 total permits, latest Jun 10, 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
Other (167152): Issued after 2 mo — above the 75th percentile for other permits in Unincorporated Marin (median 0d, 75th pct 1d, n=1,560).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (review-time benchmark)
- ! 5 slow or stalled nearby projects within ½ mile
Closest lead: New home at 217 Cleveland Ave (0.11 mi NE, 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 (~$25,750/yr at $2,200,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,146/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:
- 11,021 sq ft (0.25 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 266 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 11,021 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: $1,936,000 – $2,464,000 · 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)
22 active or recent development projects (19 housing units across completed, permitted, and pipeline stages) and 589 total building permits recorded within ½ mile.
- New construction13 permits (2 units)
- Adds housing (ADU)17 permits (17 units)
- Demolition2 permits
- Additions & renovations37 permits
- Building systems423 permits
- Repairs21 permits
- Other76 permits
Developments Deserving Closer Investigation & Active Area Builders
- New home at 217 Cleveland Ave (Issued)0.11 mi NE
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)0.25 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).
- New commercial building at 100 Harvard Ave (Issued)0.33 mi NW
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 249 Perry St (Applied)0.17 mi E
In "Applied" for 2 yr (since Oct 31, 2024), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
Entity-resolved builders & contractors in ½ mile: Golden Gate Home Improvement (3 on parcel, 3 in ½ mi · Windows / doors / siding); Westward Builders (1 on parcel, 1 in ½ mi · General repair); Clough Construction (1 on parcel, 1 in ½ mi · Other); Ken Cooper Roofing And Gutter (1 on parcel, 1 in ½ mi · Roof replacement); James S Clough Enterprises (1 on parcel, 1 in ½ mi · Other).
Permit & Project History on This Parcel (8 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B38307 | Roof replacement | Issued | Iss. Jun 10, 2024 | $42,958 | Re-Roofing: Removed old roof and install new Class A Material. — ReRoofing; With Electronic Inspection |
| 167152 | Other | Issued | Iss. Feb 12, 2021 | $68,000 | Remove, Rplc & Add To Front/Side Deck & Stairs T.D. 1-5-21 |
| 166482 | Other | Issued | Iss. Dec 4, 2020 | $31,000 | Remove/Rplc Deck T.D. 11-19-20 |
| 166363 | Windows / doors / siding | Issued | Iss. Nov 24, 2020 | $67,680 | Replace Some Windows In Kind; Repl 3wndws & Slider W/ Much Wider Slider; Add Beams |
| B24102 | Roof replacement | Issued | Iss. Nov 6, 2020 | $74,863 | Tear off existing shingles and install approximately 3300 sq. ft. of Hardie siding. — Siding Replacement |
| B23782 | Windows / doors / siding | Issued | Iss. Oct 8, 2020 | $27,348 | Replace (6) windows, same size as existing. Replace shingles around windows with James Hardie shingles. — Siding Replace… |
| 165880 | General repair | Issued | Iss. Oct 1, 2020 | $100,000 | Retaining Wall |
| 164040 | Remodel / interior alteration | Issued | Iss. Jan 24, 2020 | $45,000 | 2 Baths Remod - Express |