840 A Stony Hill Rd
Tiburon 94920 · Tiburon · Coordinates: 37.88610, -122.47224
Executive Verdict · Public-Records Synthesis
Zoned R-1 in Tiburon with likely ADU & SB 9 infill eligibility and zero mapped flood, fire, or fault hazard overlaps; benchmark value $3,734,000 ($3,174,000–$4,294,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R-1 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 20,125 sq ft lot.
Source: Tiburon zoning · CA Gov. Code 66314 & 65852.21
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)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: New home (380 ft S, 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)
- ! Bulk building permits not published for Tiburon
Permit counts and nearby activity on this page may omit municipal counter records. Request a parcel permit report directly from the local building department.
Source: Source coverage registry (Tiburon)
- ! Year 1 Prop 13 tax reset (~$43,391/yr at $3,734,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$3,616/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:
- 20,125 sq ft (0.46 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 840A STONY HILL RD; 840B STONY HILL RD; 840 STONY HILL RD
Zoning & Land Use
R-1 — Single Family Residential (Tiburon)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R-1 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R-1, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R-1, a single-family residential zone. The lot is 20,125 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
- Not in a State-mapped fire hazard severity zone
- 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: $3,174,000 – $4,294,000 · 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
Nearby Activity (½ mile radius, since —)
4 active or recent development projects (4 housing units across completed, permitted, and pipeline stages) and 0 total building permits recorded within ½ mile.
Developments Deserving Closer Investigation & Active Area Builders
- New home (Issued)380 ft S
Active in "Issued" for 8.5 yr (first record May 22, 2018) with no new permit activity recorded in 8.5 yr.
- New home (Issued)0.2 mi SE
Active in "Issued" for 7.4 yr (first record Jun 18, 2019) with no new permit activity recorded in 7.4 yr.
- New home (Issued)0.22 mi NW
Active in "Issued" for 2.2 yr (first record Sep 10, 2024) with no new permit activity recorded in 2.2 yr.
- New home (Issued)0.25 mi S
Active in "Issued" for 23 mo (first record Dec 17, 2024) with no new permit activity recorded in 23 mo.
Permit & Project History on This Parcel (0 permits, 1 grouped projects)
No building permits recorded on this parcel in our dataset.
State HCD Housing Element APR records on this parcel: 1 entry (report years 2024).