23 Hillcrest Rd
Tiburon 94920 · Unincorporated Tiburon · Unincorporated Marin · Coordinates: 37.90361, -122.48067
Executive Verdict · Public-Records Synthesis
Zoned R1-B2 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 $3,222,000 ($2,835,000–$3,609,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1-B2 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 14,854 sq ft lot.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$21,864 contributory est.)
Public building records show issued construction/renovation work on this parcel (7 total permits, latest Jan 10, 2026).
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 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: New home (0.5 mi SW, entitled). 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 (~$37,503/yr at $3,222,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$3,125/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:
- 14,854 sq ft (0.34 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 23 HILLCREST RD
Zoning & Land Use
R1-B2 — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R1-B2 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R1-B2, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1-B2, a single-family residential zone. The lot is 14,854 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 06041C0488E, 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: $2,835,000 – $3,609,000 · Status: Off market
HUD Small Area FMR (ZIP 94920) · FY 2026
Studio $2,820 · 1BR $3,380 · 2BR $4,100 · 3BR $5,230 · 4BR $5,420
Developments Deserving Closer Investigation & Active Area Builders
- New home (Entitled)0.5 mi SW
In "Entitled" for 8.1 yr (since Sep 20, 2018), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
- New home (Issued)500 ft SE
Active in "Issued" for 3.8 yr (first record Feb 9, 2023) with no new permit activity recorded in 3.8 yr.
- New home (Issued)0.28 mi SE
Active in "Issued" for 2.2 yr (first record Sep 11, 2024) with no new permit activity recorded in 2.2 yr.
- New home (Issued)0.33 mi SW
Active in "Issued" for 17 mo (first record Jun 18, 2025) with no new permit activity recorded in 17 mo.
Entity-resolved builders & contractors in ½ mile: Byron Smith General Contractor (3 on parcel, 3 in ½ mi · Electrical / panel); Gutierrez Roofing (1 on parcel, 1 in ½ mi · Roof replacement); Design Build Specialits (1 on parcel, 1 in ½ mi · Windows / doors / siding); Moore Services (1 on parcel, 1 in ½ mi · HVAC / heat pump); Owner (3 in ½ mi · New garage / accessory structure).
Permit & Project History on This Parcel (7 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B45415 | Roof replacement | Issued | Iss. Jan 10, 2026 | $61,401 | Remove existing Flat roof membrane .and wood shakes roof at pitch roof. Install class A modified asphalt roof membrane w… |
| B42092 | Windows / doors / siding | Issued | Iss. Apr 18, 2025 | $28,000 | Replace front & side entry doors — Non-structural Door/Window Replacement |
| 173869 | Remodel / interior alteration | Issued | Iss. Apr 24, 2023 | $8,900 | Bath Remodel - Express |
| B25957 | HVAC / heat pump | Issued | Iss. Jun 7, 2021 | $4,200 | 96% 110K BTU FAU ADD ON IN BASEMENT. — Mechanical Appliance |
| 165144 | Remodel / interior alteration | Issued |