233 Johnstone Dr
San Rafael 94903 · Marinwood · Unincorporated Marin · Coordinates: 38.04134, -122.53762
Executive Verdict · Public-Records Synthesis
Zoned R1-B2 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and mapped CAL FIRE high fire hazard severity zone (local responsibility area) due diligence; benchmark value $1,365,000 ($1,201,000–$1,529,000).
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 12,327 sq ft lot. Local precedent is active with 1 ADU permit within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$37,400 contributory est.)
Public building records show issued construction/renovation work on this parcel (6 total permits, latest Jul 1, 2024).
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 (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)
- ! Delayed or open permit activity on this parcel
Remodel / interior alteration (175316): Issued after 5 mo (1.8× the 83d median) — above the 75th percentile for remodel / interior alteration permits in Unincorporated Marin (median 83d, 75th pct 148d, n=1,054).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (review-time benchmark)
- ! 5 slow or stalled nearby projects within ½ mile
Closest lead: 125 new homes (0.3 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)
Parcel & Assessor
- Lot size:
- 12,327 sq ft (0.28 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 233 JOHNSTONE DR
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 12,327 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 (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 06041C0291D, effective May 4, 2009
- CGS Alquist-Priolo Earthquake Fault Zone
- Not in an Alquist-Priolo Earthquake Fault Zone
Surrounding Rent & Value Benchmarks (Public Records)
Range: $1,201,000 – $1,529,000 · Status: Off market
HUD Small Area FMR (ZIP 94903) · FY 2026
Studio $2,880 · 1BR $3,450 · 2BR $4,180 · 3BR $5,340 · 4BR $5,530
Developments Deserving Closer Investigation & Active Area Builders
- 125 new homes (Entitled)0.3 mi SW
In "Entitled" for 23 mo (since Dec 6, 2024), exceeding the 292d median and 313d 90th percentile for new multifamily / condos / mixed-use permits in Unincorporated Marin (n=21). High-impact scale (125 housing units, 124 deed-restricted affordable across 0 permits).
- Remodel / interior alteration (175316) (Issued)On this parcel
Issued after 5 mo (1.8× the 83d median) — above the 75th percentile for remodel / interior alteration permits in Unincorporated Marin (median 83d, 75th pct 148d, n=1,054).
- Accessory dwelling unit at 2558 Heatherstone Dr (Applied)0.45 mi SW
In "Applied" for 5.5 yr (since Apr 29, 2021), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
- Demolition at 249 Johnstone Dr (Issued)270 ft S
Active in "Issued" for 8.7 yr (first record Mar 15, 2018) with no new permit activity recorded in 8.6 yr.
Entity-resolved builders & contractors in ½ mile: Owner Builder (1 on parcel, 29 in ½ mi · Remodel / interior alteration); Owner (2 on parcel, 20 in ½ mi · Remodel / interior alteration); Marin Home Remodeling (1 on parcel, 1 in ½ mi · Remodel / interior alteration); Apollo Building And Roofing Group (1 on parcel, 1 in ½ mi · Roof replacement); Rps Remodeling (1 on parcel, 1 in ½ mi · Windows / doors / siding).
Permit & Project History on This Parcel (6 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B38582 | Windows / doors / siding | Issued | Iss. Jul 1, 2024 | $7,000 | Install James Hardie fiber cement siding to front exterior walls of home. Approx. 500 sq.ft. — Siding Replacement |
| 175316 | Remodel / interior alteration | Issued | Iss. Oct 26, 2023 | $50,000 | Kitchen Remodel Including Removal Of Load-Bearing Wall |
| B34391 | Roof replacement | Issued | Iss. Jun 21, 2023 | $19,933 | 25SQ tear off and to install 22/25SQ OC True Def Cool in the color Mountainside and 3/25SQ 3 ply torch by Certain Teed i… |
| B27673 | HVAC / heat pump | Issued | Iss. Nov 5, 2021 | $13,000 | Remember place ducts and install air conditioning — New Ductwork, Replace Ductwork, Mechanical Appliance |
| B27468 | Electrical / panel |