129 Peralta Ave
Mill Valley 94941 · Tamalpais · Unincorporated Marin · Coordinates: 37.88704, -122.53341
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 $2,241,000 ($1,972,000–$2,510,000).
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 12,327 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 (+$53,640 contributory est.)
Public building records show issued construction/renovation work on this parcel (6 total permits, latest Nov 27, 2023).
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
Accessory dwelling unit (new or conversion) (88378): Pending in review for 5.4 yr (9.7× the 204d median) — slower than 90% of accessory dwelling unit (new or conversion) permits in Unincorporated Marin (median 204d, 90th pct 549d, n=298).
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 (0.41 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)
- ! Year 1 Prop 13 tax reset (~$26,222/yr at $2,241,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,185/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:
- 12,327 sq ft (0.28 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 129 PERALTA 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 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
- 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: $1,972,000 – $2,510,000 · 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)0.41 mi W
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).
- Accessory dwelling unit (new or conversion) (88378) (Applied)On this parcel
Pending in review for 5.4 yr (9.7× the 204d median) — slower than 90% of accessory dwelling unit (new or conversion) permits in Unincorporated Marin (median 204d, 90th pct 549d, n=298).
- New commercial building at 100 Harvard Ave (Issued)0.1 mi N
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)0.25 mi E
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).
Entity-resolved builders & contractors in ½ mile: Hendrickson Pools (1 on parcel, 3 in ½ mi · Pool / spa); True North Construction (2 on parcel, 2 in ½ mi · New garage / accessory structure); Sustainable Living Builders (1 on parcel, 1 in ½ mi · Solar / battery storage); Aka Electric (1 on parcel, 1 in ½ mi · Electrical / panel); Owner Builder (106 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (6 permits, 1 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B36229 | Solar / battery storage | Issued | Iss. Nov 27, 2023 | $79,700 | Installing 30 panel solar system (12 kW), also installing two batteries equalling 27 kWh. |
| 171988 | Pool / spa | Issued | Iss. Jul 26, 2022 | $186,238 | New In-Ground Pool & Spa W/ Safety Cover |
| 169426 | New garage / accessory structure | Issued | Iss. Sep 24, 2021 | $60,000 | Retaining Wall; Deck; Outdoor Kitchen; Pool Equip Enclosure |
| 169425 | New single-family home | Issued | Iss. Sep 24, 2021 | $1,540,000 |