280 Richardson Dr
Mill Valley 94941 · Strawberry · Unincorporated Marin · Coordinates: 37.89246, -122.50587
Executive Verdict · Public-Records Synthesis
Zoned R1-B2 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and zero mapped flood, fire, or fault hazard overlaps; benchmark value $2,227,000 ($1,960,000–$2,494,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1-B2 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 10,367 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 (+$7,271 contributory est.)
Public building records show issued construction/renovation work on this parcel (2 total permits, latest Nov 22, 2023).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
- ✓ Above-average reinvestment in Strawberry
43 substantial renovation & housing permits over 24 months (28.4 per 1,000 parcels vs. 16.4 citywide baseline) (#1 of 22 neighborhoods).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (Strawberry)
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
New garage / accessory structure (91551): Pending in review for 3.1 yr (6.9× the 164d median) — slower than 90% of new garage / accessory structure permits in Unincorporated Marin (median 164d, 90th pct 485d, n=356).
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 218 Meda Ln (0.11 mi W, 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 (~$26,061/yr at $2,227,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,172/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:
- 10,367 sq ft (0.24 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 280 RICHARDSON DR
Zoning & Land Use
R1-B2 — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R1-B2 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R1-B2, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1-B2, a single-family residential zone. The lot is 10,367 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: $1,960,000 – $2,494,000 · 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 218 Meda Ln (Applied)0.11 mi W
In "Applied" for 6.5 yr (since Apr 30, 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, $850,000 declared valuation across 1 permit).
- New garage / accessory structure (91551) (Applied)On this parcel
Pending in review for 3.1 yr (6.9× the 164d median) — slower than 90% of new garage / accessory structure permits in Unincorporated Marin (median 164d, 90th pct 485d, n=356).
- New home at 82 Vista Del Sol (Issued)0.3 mi NW
Active in "Issued" for 12.3 yr (first record Aug 7, 2014) with no new permit activity recorded in 12.1 yr. High-impact scale (1 housing unit, $1,000,000 declared valuation across 1 permit).
- New home at 153 Richardson Dr (adu 153a) (Issued)0.36 mi N
Active in "Issued" for 3.4 yr (first record Jun 5, 2023) with no new permit activity recorded in 16 mo. High-impact scale (1 housing unit, $1,493,000 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: Sunpower (1 on parcel, 1 in ½ mi · Solar / battery storage); Regency General Contractors (151 in ½ mi · Remodel / interior alteration); Owner Builder (54 in ½ mi · Remodel / interior alteration); Owner (39 in ½ mi · Remodel / interior alteration); Kerr Construction (6 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (2 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B36207 | Solar / battery storage | Issued | Iss. Nov 22, 2023 | $18,360 | INSTALLATION OF ROOF-MOUNTED PV SYSTEM - 8.93 KW (21 MODULES) WITH (N)100A LOAD CENTER |
| 91551 | New garage / accessory structure | Applied | App. Oct 5, 2023 | $500,000 | Struct Convertion (E) Garage To (N) Living; (N) Garage; Deck; Ret Wall T.D. 11-10-23 |