5 Carolyn Ln
Mill Valley 94941 · Almonte · Unincorporated Marin · Coordinates: 37.88934, -122.53268
Executive Verdict · Public-Records Synthesis
Zoned R1 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and zero mapped flood, fire, or fault hazard overlaps; benchmark value $2,146,000 ($1,888,000–$2,404,000).
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 8,233 sq ft lot. Local precedent is active with 4 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$13,662 contributory est.)
Public building records show issued construction/renovation work on this parcel (5 total permits, latest Aug 7, 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)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: New commercial building at 100 Harvard Ave (330 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)
- ! Year 1 Prop 13 tax reset (~$25,129/yr at $2,146,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,094/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:
- 8,233 sq ft (0.19 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 5 CAROLYN LN
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 8,233 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 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: $1,888,000 – $2,404,000 · 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
Developments Deserving Closer Investigation & Active Area Builders
- New commercial building at 100 Harvard Ave (Issued)330 ft S
Active in "Issued" for 23 mo (first record Dec 26, 2024) with no new permit activity recorded in 18 mo. High-impact scale ($6,500,000 declared valuation across 1 permit).
- Accessory dwelling unit at 131 Yale Ave A (Issued)0.22 mi SE
Active in "Issued" for 4.8 yr (first record Jan 19, 2022) with no new permit activity recorded in 3.4 yr. High-impact scale (1 housing unit, $1,000,000 declared valuation across 1 permit).
- 2 new homes (Issued)0.27 mi N
Active in "Issued" for 5.7 yr (first record Mar 1, 2021) with no new permit activity recorded in 5.7 yr. High-impact scale (2 housing units, 1 deed-restricted affordable across 0 permits).
- 2 new homes (Issued)0.28 mi N
Active in "Issued" for 5.7 yr (first record Mar 1, 2021) with no new permit activity recorded in 5.7 yr. High-impact scale (2 housing units, 1 deed-restricted affordable across 0 permits).
Entity-resolved builders & contractors in ½ mile: Golden Heights Remodeling (1 on parcel, 1 in ½ mi · Roof replacement); Infinity Energy (1 on parcel, 1 in ½ mi · Solar / battery storage); Freedom Forever (1 on parcel, 1 in ½ mi · Solar / battery storage); Perez Solar Panels (1 on parcel, 1 in ½ mi · Other); C Wells Electrical (1 on parcel, 1 in ½ mi · EV charger).
Permit & Project History on This Parcel (5 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B47782 | Other | Issued | Iss. Aug 7, 2026 | $15,000 | — |
| B44231 | Roof replacement | Issued | Iss. Oct 7, 2025 | $25,000 | Demo and install existing roof approx. 2563 sqft. — ReRoofing |
| B34303 | EV charger | Issued | Iss. Jun 15, 2023 | $1,997 | Istallation of NEMA 14-50 outlet with 50 amp GFCI — EV Charging Station |
| 166502 | Solar / battery storage | Issued | Iss. Dec 8, 2020 | $21,000 | Energy Storage System |
| 161934 | Solar / battery storage | Issued | Iss. Jun 27, 2019 | $20,000 |