139 Richardson Dr
Mill Valley 94941 · Strawberry · Unincorporated Marin · Coordinates: 37.89883, -122.50798
Executive Verdict · Public-Records Synthesis
Zoned R1 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and zero mapped flood, fire, or fault hazard overlaps; benchmark value $2,158,000 ($1,899,000–$2,417,000).
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 5,576 sq ft lot. Local precedent is active with 12 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$43,040 contributory est.)
Public building records show issued construction/renovation work on this parcel (14 total permits, latest Jul 9, 2025).
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
Addition (adds square footage) (88742): Pending in review for 5.3 yr (12.0× the 160d median) — slower than 90% of addition (adds square footage) permits in Unincorporated Marin (median 160d, 90th pct 440d, n=316).
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 (0.42 mi S, 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 (~$25,267/yr at $2,158,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,106/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:
- 5,576 sq ft (0.13 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 139 RICHARDSON DR
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 5,576 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: $1,899,000 – $2,417,000 · 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)0.42 mi S
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).
- Addition (adds square footage) (88742) (Applied)On this parcel
Pending in review for 5.3 yr (12.0× the 160d median) — slower than 90% of addition (adds square footage) permits in Unincorporated Marin (median 160d, 90th pct 440d, n=316).
- New home at 153 Richardson Dr (adu 153a) (Issued)510 ft SE
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).
- New commercial building at 118 E Strawberry Dr (Applied)0.12 mi SE
Active in "Applied" for 8.1 yr (first record Oct 3, 2018) with no new permit activity recorded in 8.1 yr. High-impact scale ($1,600,000 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: Owner Builder (2 on parcel, 70 in ½ mi · Remodel / interior alteration); Owner (1 on parcel, 44 in ½ mi · Remodel / interior alteration); Maap (2 on parcel, 2 in ½ mi · Windows / doors / siding); The Home Doctors (1 on parcel, 1 in ½ mi · Remodel / interior alteration); Im Roofing (1 on parcel, 1 in ½ mi · Roof replacement).
Permit & Project History on This Parcel (14 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B43048 | Plumbing / water heater / sewer | Issued | Iss. Jul 9, 2025 | $5,000 | Remove & replace 40 gallon water heater in crawlspace like for like. — Replace Plumbing Fixtures(s) |
| B41381 | Windows / doors / siding | Issued | Iss. Feb 24, 2025 | $17,375 | Replacing (9) windows w/vinyl-retrofit installation — Non-structural Door/Window Replacement |
| B40145 | Windows / doors / siding | Issued | Iss. Nov 11, 2024 | $11,193 | Replacing 7 windows in-kind w/vinyl, retrofit installation — Non-structural Door/Window Replacement |
| B29512 | Windows / doors / siding | Issued | Iss. Apr 25, 2022 | $11,416 | Replace 4 windows with nail fin vinyl windows — Non-structural Door/Window Replacement |
| 171011 | Remodel / interior alteration |