100 Mt Lyell Dr
San Rafael 94903 · Lucas Valley · Unincorporated Marin · Coordinates: 38.03281, -122.57733
Executive Verdict · Public-Records Synthesis
Zoned R1-B-LV 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 $1,430,000 ($1,258,000–$1,602,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1-B-LV supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 12,676 sq ft lot. Local precedent is active with 2 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ 5 documented municipal building permits on file
On-parcel permit history is indexed through Mar 20, 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 (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
HVAC / heat pump (179269): Issued after 2 mo — slower than 90% of hvac / heat pump permits in Unincorporated Marin (median 0d, 90th pct 0d, n=2,946).
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: Accessory dwelling unit at 42 Oak Mountain Ct (0.26 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)
Parcel & Assessor
- Lot size:
- 12,676 sq ft (0.29 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 100 MT LYELL DR
Zoning & Land Use
R1-B-LV — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R1-B-LV (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R1-B-LV, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1-B-LV, a single-family residential zone. The lot is 12,676 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 06041C0287D, 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: $1,258,000 – $1,602,000 · 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
Nearby Activity (½ mile radius, since November 2024)
4 active or recent development projects (3 housing units across completed, permitted, and pipeline stages) and 228 total building permits recorded within ½ mile.
- New construction1 permit
- Adds housing (ADU)3 permits (3 units)
- Demolition3 permits
- Additions & renovations11 permits
- Building systems164 permits
- Repairs3 permits
- Other43 permits
Developments Deserving Closer Investigation & Active Area Builders
- HVAC / heat pump (179269) (Issued)On this parcel
Issued after 2 mo — slower than 90% of hvac / heat pump permits in Unincorporated Marin (median 0d, 90th pct 0d, n=2,946).
- Accessory dwelling unit at 42 Oak Mountain Ct (Applied)0.26 mi W
In "Applied" for 5.5 yr (since Apr 30, 2021), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
- Demolition at 2000 Lucas Valley Rd (Applied)0.36 mi W
In "Applied" for 4.4 yr (since Jun 7, 2022), exceeding the 55d median and 261d 90th percentile for demolition permits in Unincorporated Marin (n=130).
- New home at 85 Pikes Peak Dr (Issued)0.19 mi SE
Active in "Issued" for 3.1 yr (first record Oct 20, 2023) with no new permit activity recorded in 2.4 yr.
Entity-resolved builders & contractors in ½ mile: John Owens Services (2 on parcel, 2 in ½ mi · Other); John Owens Service (1 on parcel, 1 in ½ mi · HVAC / heat pump); Abril Roofing (1 on parcel, 1 in ½ mi · Roof replacement); Owner Builder (23 in ½ mi · Remodel / interior alteration); Owner (9 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (5 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| 94077 | Pool / spa | Applied | App. Mar 20, 2026 | $110,000 | New Pool & Spa With Automatic Cover |
| 179269 | HVAC / heat pump | Issued | Iss. May 15, 2025 | $21,711 | Install (2) Hp Minisplit Systems - (1) 20k Outdoor Hp Minisplit (1) 12k For Master Bedroom And (1) 9k For Bdrm, (1) 18k … |
| B25208 | Roof replacement | Issued | Iss. Mar 19, 2021 | $20,000 | Apply polyurethane foam roof over tar and gravel roof one layer on 2 flat sections only — ReRoofing |
| B24999 | Plumbing / water heater / sewer | Issued | Iss. Mar 1, 2021 | $15,837 | Replace electrical panel and gas line — Service Upgrade; New Gas Service, Replace Plumbing Fixtures(s) |
| B22517 | Other | Issued | Iss. May 6, 2020 | $9,896 | Install new Rinnai I090SN 90K Btu/hr Condensing Boiler in the same location — Replace Mechanical Appliance |