112 Grace Ln
Mill Valley 94941 · Alto · Unincorporated Marin · Coordinates: 37.90613, -122.52565
Executive Verdict · Public-Records Synthesis
Zoned RA-B2 in Unincorporated Marin with likely ministerial ADU eligibility and zero mapped flood, fire, or fault hazard overlaps; benchmark value $2,350,000 ($2,068,000–$2,632,000).
Upsides & Opportunities
- ✓ Ministerial ADU / JADU pathway likely eligible
Zone RA-B2 allows residential use qualifying for ministerial ADU review under state law (2 ADU permits permitted within ¼ mile in 36 months).
Source: Unincorporated Marin zoning · CA Gov. Code 66314
- ✓ Documented permitted upgrades (+$146,082 contributory est.)
Public building records show issued construction/renovation work on this parcel (4 total permits, latest Oct 15, 2025).
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)
- ! Delayed or open permit activity on this parcel
Addition (adds square footage) (169465): Issued after 10 mo (2.0× the 160d median) — above the 75th percentile for addition (adds square footage) permits in Unincorporated Marin (median 160d, 75th pct 249d, n=316).
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: 25 new homes (0.43 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)
- ! Year 1 Prop 13 tax reset (~$27,475/yr at $2,350,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,290/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:
- 13,329 sq ft (0.31 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 112 GRACE LN
Zoning & Land Use
RA-B2 — Residential Agriculture (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RA-B2 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotCan't tell
Zoned RA-B2 (single-family residential): we can't tell whether it counts as a single-family zone for SB 9. Residential agriculture, estate and restricted: large-lot residential; confirm SB 9 with the county.
- SB 9: split into two lotsCan't tell
Zoned RA-B2 (single-family residential): we can't tell whether it counts as a single-family zone for SB 9. Residential agriculture, estate and restricted: large-lot residential; confirm SB 9 with the county.
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 06041C0469F, 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: $2,068,000 – $2,632,000 · 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
- 25 new homes (Entitled)0.43 mi SW
In "Entitled" for 3.5 yr (since May 6, 2023), exceeding the 292d median and 313d 90th percentile for new multifamily / condos / mixed-use permits in Unincorporated Marin (n=21). High-impact scale (25 housing units, 6 deed-restricted affordable across 0 permits).
- New home at 30 Shell Rd (Issued)0.39 mi E
Active in "Issued" for 2.4 yr (first record Jul 5, 2024) with no new permit activity recorded in 22 mo. High-impact scale (1 housing unit, $2,800,000 declared valuation across 1 permit).
- Accessory dwelling unit at 55 Plaza Dr (adu 55a) (Issued)0.44 mi E
Active in "Issued" for 2.6 yr (first record Apr 17, 2024) with no new permit activity recorded in 19 mo. High-impact scale (1 housing unit, $790,000 declared valuation across 1 permit).
- Accessory dwelling unit at 70 Shell Rd (Applied)0.12 mi E
In "Applied" for 4.2 yr (since Aug 18, 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: Baldenebro Construction (2 on parcel, 2 in ½ mi · Addition (adds square footage)); Solar Optimum (1 on parcel, 1 in ½ mi · Solar / battery storage); Tesla Energy Operations (1 on parcel, 1 in ½ mi · Solar / battery storage); Owner Builder (15 in ½ mi · Addition (adds square footage)); Drosihn Construction (3 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 |
|---|---|---|---|---|---|
| B44362 | Solar / battery storage | Issued | Iss. Oct 15, 2025 | $21,000 | Install 3 battery backups |
| B32721 | Solar / battery storage | Issued | Iss. Feb 23, 2023 | $40,000 | Install 40 Roof Mount Solar Panels 16.00KW |
| 170632 | Remodel / interior alteration | Issued | Iss. Feb 11, 2022 | $35,000 | Interior Remodel: (2) Upstairs Baths & Downstairs Powder Rm - Express |
| 169465 | Addition (adds square footage) | Issued | Iss. Sep 29, 2021 | $175,000 | Remod, Convsn, Addtn, Windws/Doors |