21 N Ridgewood Rd
Kentfield 94904 · Kentfield · Unincorporated Marin · Coordinates: 37.95052, -122.55970
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 $2,469,000 ($2,173,000–$2,765,000).
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 36,155 sq ft lot. Local precedent is active with 5 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ 2 documented municipal building permits on file
On-parcel permit history is indexed through Sep 29, 2026, letting you verify roof, HVAC, electrical, or structural work against seller disclosures.
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 (0.18 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 (~$28,844/yr at $2,469,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,404/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:
- 36,155 sq ft (0.83 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 21 N 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 36,155 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: $2,173,000 – $2,765,000 · 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)0.18 mi W
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).
- Accessory dwelling unit at 31 N Ridgewood Rd (adu 31a) (Issued)280 ft 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).
- New home at 9 N Ridgewood Rd (Issued)290 ft SE
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).
- New home at 36 N Ridgewood Rd (Issued)370 ft NE
Active in "Issued" for 10.5 yr (first record May 19, 2016) with no new permit activity recorded in 9.9 yr. High-impact scale (1 housing unit, $2,500,000 declared valuation across 3 permits).
Entity-resolved builders & contractors in ½ mile: Herbs Pool Service (1 on parcel, 7 in ½ mi · Pool / spa); Ernest Ongaro And Sons (1 on parcel, 2 in ½ mi · Accessory dwelling unit (new or conversion)); Owner Builder (49 in ½ mi · Remodel / interior alteration); Owner (15 in ½ mi · Remodel / interior alteration); Hendrickson Pools (9 in ½ mi · Pool / spa).
Permit & Project History on This Parcel (2 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| 182731 | General repair | Applied | App. Sep 29, 2026 | $22,165 | Minor Pool Remodel. Strip Plaster, Undercut Waterline Tile To Save, Apply New Plaster Material To Pool Interior. |
| B44041 | Plumbing / water heater / sewer | Issued | Iss. Sep 24, 2025 | $2,844 | Remove (E)NG tanked WH located in closet Install(N) NG 30G tanked WH in same location — Replace Plumbing Fixtures(s) |