13 Alturas Way
Mill Valley 94941 · Tamalpais · Unincorporated Marin · Coordinates: 37.88877, -122.53589
Executive Verdict · Public-Records Synthesis
Zoned RSP-2.75 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and mapped CAL FIRE moderate fire hazard severity zone (state responsibility area) due diligence; benchmark value $2,133,000 ($1,877,000–$2,389,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned RSP-2.75 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 8,276 sq ft lot. Local precedent is active with 6 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$11,275 contributory est.)
Public building records show issued construction/renovation work on this parcel (3 total permits, latest Jun 5, 2026).
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)
- ! CAL FIRE Moderate Fire Hazard Severity Zone (State 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 Apr 1, 2024)
- ! Delayed or open permit activity on this parcel
Remodel / interior alteration (93764): Pending in review for 11 mo (4.2× the 83d median) — slower than 90% of remodel / interior alteration permits in Unincorporated Marin (median 83d, 90th pct 266d, n=1,054).
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: New home at 560 Alta Way (0.34 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)
Parcel & Assessor
- Lot size:
- 8,276 sq ft (0.19 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 13 ALTURAS WAY
Zoning & Land Use
RSP-2.75 — Residential Single Family Planned (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned RSP-2.75 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned RSP-2.75, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned RSP-2.75, a single-family residential zone. The lot is 8,276 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
- Moderate Fire Hazard Severity Zone (State Responsibility Area) (all of the lot, map Apr 1, 2024)
- 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: $1,877,000 – $2,389,000 · 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)0.34 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).
- Remodel / interior alteration (93764) (Applied)On this parcel
Pending in review for 11 mo (4.2× the 83d median) — slower than 90% of remodel / interior alteration permits in Unincorporated Marin (median 83d, 90th pct 266d, n=1,054).
- New commercial building at 100 Harvard Ave (Issued)0.16 mi E
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).
- 2 new homes (Issued)0.36 mi NE
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 Gate Home Improvement (1 on parcel, 1 in ½ mi · Windows / doors / siding); G Moran Construction (1 on parcel, 1 in ½ mi · Remodel / interior alteration); Owner Builder (101 in ½ mi · Remodel / interior alteration); Owner (47 in ½ mi · Remodel / interior alteration); Juan Calmell (6 in ½ mi · Remodel / interior alteration).
Permit & Project History on This Parcel (3 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| 181775 | Remodel / interior alteration | Issued | Iss. Jun 5, 2026 | $20,500 | Remodel Master Bathroom. |
| 93764 | Remodel / interior alteration | Applied | App. Dec 2, 2025 | $48,250 | Remodel Master Bathroom And Master Bedroom. |
| B26616 | Windows / doors / siding | Issued | Iss. Aug 12, 2021 | $22,972 | Replace (14) windows, same size as existing. — Non-structural Door/Window Replacement |