21 S Ridgewood Rd
Kentfield 94904 · Kentfield · Unincorporated Marin · Coordinates: 37.94741, -122.55898
Executive Verdict · Public-Records Synthesis
Zoned RSP-1 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and mapped CAL FIRE moderate fire hazard severity zone (state responsibility area) due diligence; benchmark value $2,501,000 ($2,201,000–$2,801,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned RSP-1 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 40,206 sq ft lot.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$31,949 contributory est.)
Public building records show issued construction/renovation work on this parcel (6 total permits, latest Apr 11, 2023).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
- ✓ Above-average reinvestment in Kentfield
104 substantial renovation & housing permits over 24 months (41.3 per 1,000 parcels vs. 16.4 citywide baseline) (#7 of 22 neighborhoods).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (Kentfield)
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)
- ! CAL FIRE Moderate Fire Hazard Severity Zone (State Responsibility Area) (all of the lot of lot)
Located in a mapped Fire Hazard Severity Zone. Expect Chapter 7A ignition-resistant building standards, defensible-space inspections, and stricter property insurance underwriting.
Source: CAL FIRE FHSZ (map Apr 1, 2024)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: Accessory dwelling unit at 432 Woodland Rd (0.31 mi NW, 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 (~$29,212/yr at $2,501,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,434/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:
- 40,206 sq ft (0.92 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 21 S RIDGEWOOD RD
Zoning & Land Use
RSP-1 — Residential Single Family Planned (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RSP-1 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned RSP-1, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned RSP-1, a single-family residential zone. The lot is 40,206 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
- Moderate Fire Hazard Severity Zone (State Responsibility Area) (all of the lot, map Apr 1, 2024)
- FEMA National Flood Hazard Layer
- Zone X: minimal flood hazard (all of the lot) · FIRM panel 06041C0458F, 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: $2,201,000 – $2,801,000 · Status: Off market
HUD Small Area FMR (ZIP 94904) · FY 2026
Studio $2,260 · 1BR $2,710 · 2BR $3,280 · 3BR $4,190 · 4BR $4,340
Developments Deserving Closer Investigation & Active Area Builders
- Accessory dwelling unit at 432 Woodland Rd (Applied)0.31 mi NW
In "Applied" for 2.6 yr (since Apr 12, 2024), 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, $1,250,000 declared valuation across 1 permit).
- New home at 6 Turnagain Rd (Issued)0.11 mi N
Active in "Issued" for 9.3 yr (first record Aug 3, 2017) with no new permit activity recorded in 9.1 yr. High-impact scale (1 housing unit, $1,196,000 declared valuation across 1 permit).
- New home at 9 N Ridgewood Rd (Issued)0.18 mi N
Active in "Issued" for 11.5 yr (first record May 14, 2015) with no new permit activity recorded in 11.3 yr. High-impact scale (1 housing unit, $1,200,000 declared valuation across 1 permit).
- Accessory dwelling unit at 31 N Ridgewood Rd (adu 31a) (Issued)0.27 mi N
Active in "Issued" for 20 mo (first record Feb 28, 2025) with no new permit activity recorded in 16 mo. High-impact scale (1 housing unit, $750,000 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: Herbs Pool Service (1 on parcel, 5 in ½ mi · Pool / spa); Hoffmann Construction (3 on parcel, 4 in ½ mi · Other); De Mello Roofing (1 on parcel, 1 in ½ mi · Roof replacement); John Owens Services (1 on parcel, 1 in ½ mi · HVAC / heat pump); Owner Builder (48 in ½ mi · Addition (adds square footage)).
Permit & Project History on This Parcel (6 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B33372 | Other | Issued | Iss. Apr 11, 2023 | $37,000 | install 38 kw generator |
| B29085 | Roof replacement | Issued | Iss. Mar 15, 2022 | $41,220 | TEAR OFF EXISTING BUILT-UP ROOF INSTALL NEW BUILT-UP ROOF CLASS A — ReRoofing |
| B15260 | HVAC / heat pump | Issued | Iss. Jun 20, 2018 | $6,700 | replace furnace & A/C add on — Mechanical Appliance, Replace Mechanical Appliance |
| 155634 | Pool / spa | Issued | Iss. Jun 5, 2017 | $35,910 | Pool Rmdl; Add Spa T.D. 5/26/17 |
| 155056 | New garage / accessory structure | Issued | Iss. Mar 30, 2017 | $28,000 |