21 Toussin Ave
Kentfield 94904 · Kentfield · Unincorporated Marin · Coordinates: 37.96029, -122.55076
Executive Verdict · Public-Records Synthesis
Zoned R1-B3 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and mapped CAL FIRE moderate fire hazard severity zone (local 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 R1-B3 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 25,483 sq ft lot. Local precedent is active with 2 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ 10 documented municipal building permits on file
On-parcel permit history is indexed through Dec 6, 2024, 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 (Local 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 Mar 24, 2025)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: Accessory dwelling unit at 66 Hanken Dr (adu 66a) (0.19 mi SE, 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 (~$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:
- 25,483 sq ft (0.59 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 21 TOUSSIN AVE
Zoning & Land Use
R1-B3 — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R1-B3 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R1-B3, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1-B3, a single-family residential zone. The lot is 25,483 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 (Local Responsibility Area) (all of the lot, map Mar 24, 2025)
- 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 66 Hanken Dr (adu 66a) (Issued)0.19 mi SE
Active in "Issued" for 3.1 yr (first record Sep 29, 2023) with no new permit activity recorded in 2.8 yr. High-impact scale (1 housing unit, $1,000,000 declared valuation across 1 permit).
- New home at 7 Cedar Ave (Issued)0.28 mi S
Active in "Issued" for 7.7 yr (first record Mar 14, 2019) with no new permit activity recorded in 5.5 yr. High-impact scale (1 housing unit, $1,217,500 declared valuation across 2 permits).
- 1 Ridgeview (Entitled)0.15 mi W
In "Entitled" for 3.6 yr (since Mar 23, 2023), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
- 3 Skyland (Entitled)0.19 mi N
In "Entitled" for 3.4 yr (since Jun 15, 2023), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
Entity-resolved builders & contractors in ½ mile: Ernest Ongaro And Sons (3 on parcel, 3 in ½ mi · Plumbing / water heater / sewer); Maap (2 on parcel, 2 in ½ mi · Windows / doors / siding); Houseworks Enterprises (2 on parcel, 2 in ½ mi · Plumbing / water heater / sewer); Valentine Builders (1 on parcel, 1 in ½ mi · New garage / accessory structure); Grc Roofing (1 on parcel, 1 in ½ mi · Roof replacement).
Permit & Project History on This Parcel (10 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B40452 | Windows / doors / siding | Issued | Iss. Dec 6, 2024 | $32,893 | Replacing 7 windows, like for like, w/Wood Clad & WUI glass, nail fin frame installation — Non-structural Door/Window Re… |
| B40045 | Plumbing / water heater / sewer | Issued | Iss. Nov 1, 2024 | $1,000 | Dig up existing clean out that has come apart & replacing it with a new SDR17 2way clean out & backflow prevention devic… |
| B29074 | EV charger | Issued | Iss. Mar 14, 2022 | $2,000 | Install a New EV charger 40Amp on a 60 Amp — EV Charging Station; With Electronic Inspection |
| B22374 | Plumbing / water heater / sewer | Issued | Iss. Mar 25, 2020 | $1,800 | Replace failed 50 gal WH with new 50 gal WH — Replace Plumbing Fixtures(s) |
| B18156 |