284 Cardinal Rd
Mill Valley 94941 · Tamalpais · Unincorporated Marin · Coordinates: 37.88003, -122.52559
Executive Verdict · Public-Records Synthesis
Zoned R1-B1 in Unincorporated Marin with likely ministerial ADU eligibility and mapped FEMA AE flood due diligence; benchmark value $2,283,000 ($2,009,000–$2,557,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone R1-B1 allows residential use qualifying for ministerial ADU review under state law (5 ADU permits permitted within ¼ mile in 36 months).
Source: Unincorporated Marin zoning · CA Gov. Code 66314
- ✓ Documented permitted upgrades (+$220,000 contributory est.)
Public building records show issued construction/renovation work on this parcel (3 total permits, latest May 15, 2026).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
- ✓ Above-average reinvestment in Tamalpais
50 substantial renovation & housing permits over 24 months (20.5 per 1,000 parcels vs. 16.4 citywide baseline) (#3 of 22 neighborhoods).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (Tamalpais)
Watchouts & Due Diligence
- ! FEMA Special Flood Hazard Area (AE, all of the lot of lot)
Zone AE: 1% annual chance flood (Special Flood Hazard Area) overlaps this parcel. Expect mandatory flood insurance for federally backed loans and floodplain elevation/mitigation rules for new units or SB 9 applications.
Source: FEMA National Flood Hazard Layer (parcel polygon)
- ! Delayed or open permit activity on this parcel
Addition (adds square footage) (91081): Pending in review for 3.5 yr (8.1× 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)
- ! 4 slow or stalled nearby projects within ½ mile
Closest lead: New commercial building at 201 Flamingo Rd (aka 205) (370 ft N, 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 (~$26,705/yr at $2,283,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,225/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:
- 5,793 sq ft (0.13 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 284 CARDINAL RD
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 lotPossible, with conditions
Zoned R1-B1, a single-family residential zone. FEMA Special Flood Hazard Area (Zone AE) covers all of the lot: the project must meet the National Flood Insurance Program floodplain standards, or the lot needs a map revision.
- SB 9: split into two lotsPossible, with conditions
Zoned R1-B1, a single-family residential zone. The lot is 5,793 sq ft by the assessor, room for two lots of at least 1,200 sq ft, each at least 40% of the original. FEMA Special Flood Hazard Area (Zone AE) covers all of the lot: the project must meet the National Flood Insurance Program floodplain standards, or the lot needs a map revision.
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 AE: 1% annual chance flood (Special Flood Hazard Area) (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: $2,009,000 – $2,557,000 · 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
- Addition (adds square footage) (91081) (Applied)On this parcel
Pending in review for 3.5 yr (8.1× the 160d median) — slower than 90% of addition (adds square footage) permits in Unincorporated Marin (median 160d, 90th pct 440d, n=316).
- Addition (adds square footage) (91080) (Applied)On this parcel
Pending in review for 3.5 yr (8.1× the 160d median) — slower than 90% of addition (adds square footage) permits in Unincorporated Marin (median 160d, 90th pct 440d, n=316).
- New commercial building at 201 Flamingo Rd (aka 205) (Issued)370 ft N
Active in "Issued" for 11.7 yr (first record Feb 17, 2015) with no new permit activity recorded in 11.2 yr. High-impact scale ($3,938,400 declared valuation across 3 permits).
- New home at 334 Dolan Ave (Issued)0.24 mi W
Active in "Issued" for 8.2 yr (first record Sep 5, 2018) with no new permit activity recorded in 8 yr. High-impact scale (1 housing unit, $759,000 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: Buildrite Bay Area (1 on parcel, 1 in ½ mi · Addition (adds square footage)); Owner Builder (68 in ½ mi · Remodel / interior alteration); Owner (47 in ½ mi · Remodel / interior alteration); Ga Higgins (8 in ½ mi · Remodel / interior alteration); Lamperti Contracting And Design (6 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (3 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| 181683 | Addition (adds square footage) | Issued | Iss. May 15, 2026 | $298,356 | (N) Front Entry Porch; Addition; Remodel |
| 91081 | Addition (adds square footage) | Applied | App. May 1, 2023 | $265,000 | Addition & Remodel: M Bed, M Bath, Living Rm, & Office |
| 91080 | Addition (adds square footage) | Applied | App. May 1, 2023 | $265,000 | Remodel, Addition Of Mstr Bedroom, Mstr Bath, Living Rm, & Office |