9 Castle Rock Dr
Mill Valley 94941 · Homestead · Unincorporated Marin · Coordinates: 37.90212, -122.55744
Executive Verdict · Public-Records Synthesis
Zoned R1 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 $2,180,000 ($1,918,000–$2,442,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 8,189 sq ft lot.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ 4 documented municipal building permits on file
On-parcel permit history is indexed through Sep 22, 2025, 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 Homestead
22 substantial renovation & housing permits over 24 months (20.7 per 1,000 parcels vs. 16.4 citywide baseline) (#2 of 22 neighborhoods).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (Homestead)
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)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: New home at 65 Ridge Ave (0.5 mi SW, 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 (~$25,520/yr at $2,180,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,127/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:
- 8,189 sq ft (0.19 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 9 CASTLE ROCK DR
Zoning & Land Use
R1 — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R1 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R1, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1, a single-family residential zone. The lot is 8,189 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 06041C0468F, 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: $1,918,000 – $2,442,000 · Status: Off market
HUD Small Area FMR (ZIP 94941) · FY 2026
Studio $2,730 · 1BR $3,270 · 2BR $3,960 · 3BR $5,060 · 4BR $5,240
Nearby Activity (½ mile radius, since November 2024)
9 active or recent development projects (9 housing units across completed, permitted, and pipeline stages) and 106 total building permits recorded within ½ mile.
- New construction3 permits
- Adds housing (ADU)2 permits (2 units)
- Additions & renovations7 permits
- Building systems75 permits
- Repairs7 permits
- Other12 permits
Developments Deserving Closer Investigation & Active Area Builders
- New home at 65 Ridge Ave (Applied)0.5 mi SW
In "Applied" for 4 yr (since Oct 27, 2022), 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, $3,000,000 declared valuation across 1 permit).
- New home at 2 Hart Ln (Issued)0.49 mi E
Active in "Issued" for 6.9 yr (first record Dec 18, 2019) with no new permit activity recorded in 5.9 yr. High-impact scale (1 housing unit, $750,000 declared valuation across 1 permit).
- Demolition at 688 Sequoia Valley Rd (Applied)0.32 mi S
In "Applied" for 3.2 yr (since Sep 6, 2023), exceeding the 55d median and 261d 90th percentile for demolition permits in Unincorporated Marin (n=130).
- Attached ADU (Entitled)0.4 mi NE
In "Entitled" for 3.9 yr (since Dec 22, 2022), 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: Shaughnessy Roofing (1 on parcel, 1 in ½ mi · Roof replacement); Damran Electric (1 on parcel, 1 in ½ mi · EV charger); Arb (1 on parcel, 1 in ½ mi · Plumbing / water heater / sewer); Owner Builder (22 in ½ mi · Remodel / interior alteration); Owner (11 in ½ mi · New garage / accessory structure).
Permit & Project History on This Parcel (4 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B43986 | Roof replacement | Issued | Iss. Sep 22, 2025 | $29,900 | Remove and replace roofing with GAF Timberline HDZ shingle with Tigerpaw synthtetic underlayment. — ReRoofing |
| 173663 | Remodel / interior alteration | Issued | Iss. Mar 28, 2023 | $5,000 | Nonstructural Bath Remodel - Express |
| B30645 | EV charger | Issued | Iss. Aug 8, 2022 | $6,000 | upgrade electrical meter box 100-amp upgrade to 200 amp and car charger. — Service Upgrade, EV Charging Station |
| B11203 | Plumbing / water heater / sewer | Issued | Iss. Oct 17, 2016 | $1,500 | Run gas line for PG&E meter relocation — New Plumbing Fixture(s) |