100 Hawthornden Way
Inverness 94937 · Inverness · Unincorporated Marin · Coordinates: 38.09803, -122.85384
Executive Verdict · Public-Records Synthesis
Zoned C-RSP-1 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and mapped CAL FIRE high fire hazard severity zone (state responsibility area) due diligence; benchmark value $1,652,000 ($1,454,000–$1,850,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned C-RSP-1 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 9,888 sq ft lot.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ 1 documented municipal building permit on file
On-parcel permit history is indexed through Jun 10, 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)
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 High 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)
- ! 3 slow or stalled nearby projects within ½ mile
Closest lead: New home at 60 Trossach Way (0.45 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 (~$19,448/yr at $1,652,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$1,621/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:
- 9,888 sq ft (0.23 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 100 HAWTHORNDEN WAY; 100 HAWTHORNDEN WAY A
Zoning & Land Use
C-RSP-1 — Residential Single Family Planned (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned C-RSP-1 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned C-RSP-1, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned C-RSP-1, a single-family residential zone. The lot is 9,888 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
- High 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 06041C0230E, effective August 15, 2017
- CGS Alquist-Priolo Earthquake Fault Zone
- Not in an Alquist-Priolo Earthquake Fault Zone
Surrounding Rent & Value Benchmarks (Public Records)
Range: $1,454,000 – $1,850,000 · Status: Off market
HUD Small Area FMR (ZIP 94937) · FY 2026
Studio $2,400 · 1BR $2,870 · 2BR $3,480 · 3BR $4,450 · 4BR $4,610
Developments Deserving Closer Investigation & Active Area Builders
- New home at 60 Trossach Way (Applied)0.45 mi W
In "Applied" for 5.9 yr (since Dec 15, 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, $1,400,000 declared valuation across 1 permit).
- Accessory dwelling unit at 125 Forres Way (Issued)0.3 mi W
Active in "Issued" for 20 mo (first record Mar 14, 2025) with no new permit activity recorded in 19 mo.
- New home at 182 Laurel Ave (Issued)0.44 mi W
Active in "Issued" for 12.9 yr (first record Dec 31, 2013) with no new permit activity recorded in 11.9 yr.
- New home at 45 Balmoral Way (Applied)0.36 mi NW
High-impact scale (1 housing unit, $1,200,000 declared valuation across 1 permit).
Entity-resolved builders & contractors in ½ mile: Ace Wiring Electric (1 on parcel, 1 in ½ mi · Electrical / panel); Owner Builder (4 in ½ mi · Remodel / interior alteration); Design Build Alliance (2 in ½ mi · Addition (adds square footage)); Juan Calmell (2 in ½ mi · Commercial tenant improvement); Owner (2 in ½ mi · Addition (adds square footage)).
Permit & Project History on This Parcel (1 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B47108 | Electrical / panel | Issued | Iss. Jun 10, 2026 | $6,000 | Service Upgrade |