391 Loring Ave
Mill Valley 94941 · Tamalpais · Unincorporated Marin · Coordinates: 37.88700, -122.53613
Executive Verdict · Public-Records Synthesis
Zoned R1-B1 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and zero mapped flood, fire, or fault hazard overlaps; benchmark value $2,249,000 ($1,979,000–$2,519,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1-B1 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 13,460 sq ft lot. Local precedent is active with 8 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$46,678 contributory est.)
Public building records show issued construction/renovation work on this parcel (5 total permits, latest Nov 9, 2021).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
- ✓ Above-average reinvestment in Tamalpais
50 substantial renovation & housing permits over 24 months (20.5 per 1,000 parcels vs. 16.4 citywide baseline) (#3 of 22 neighborhoods).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (Tamalpais)
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)
- ! Delayed or open permit activity on this parcel
New single-family home (80045): Pending in review for 9.5 yr (13.7× the 253d median) — slower than 90% of new single-family home permits in Unincorporated Marin (median 253d, 90th pct 686d, n=121).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (review-time benchmark)
- ! 4 slow or stalled nearby projects within ½ mile
Closest lead: New home at 560 Alta Way (0.27 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 (~$26,314/yr at $2,249,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,193/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:
- 13,460 sq ft (0.31 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 391 LORING AVE
Zoning & Land Use
R1-B1 — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R1-B1 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R1-B1, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1-B1, a single-family residential zone. The lot is 13,460 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: $1,979,000 – $2,519,000 · 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 home at 560 Alta Way (Applied)0.27 mi SW
In "Applied" for 3.3 yr (since Aug 10, 2023), 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, $975,000 declared valuation across 1 permit).
- New single-family home (80045) (Applied)On this parcel
Pending in review for 9.5 yr (13.7× the 253d median) — slower than 90% of new single-family home permits in Unincorporated Marin (median 253d, 90th pct 686d, n=121).
- New commercial building at 100 Harvard Ave (Issued)0.2 mi NE
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).
- New home at 391 Loring Ave (Finaled / completed)On this parcel
High-impact scale (1 housing unit, $1,500,000 declared valuation across 2 permits).
Entity-resolved builders & contractors in ½ mile: Hendrickson Pools (1 on parcel, 3 in ½ mi · Pool / spa); Zion Engineering (1 on parcel, 2 in ½ mi · New single-family home); Tesla Energy (2 on parcel, 2 in ½ mi · Solar / battery storage); Owner Builder (104 in ½ mi · Remodel / interior alteration); Owner (58 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (5 permits, 1 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| 169873 | Pool / spa | Issued | Iss. Nov 9, 2021 | $80,000 | Existing Deck Modification And Pool Installation |
| 165743 | Solar / battery storage | Issued | Iss. Sep 16, 2020 | $26,075 | 8.16 Photovoltaic & Energy Storage System |
| 161900 | Solar / battery storage | Issued | Iss. Jun 25, 2019 | $14,000 | Battery Backup - Express |
| 155992 | New single-family home | Issued | Iss. Jul 13, 2017 | $625,000 | S F D; Gar; Deck; Covered Porch **Sandy Stadtler 415-740-9058, Sstadtler@Gmail.Com |