Mill Valley 94941 · Alto · APN 033-071-42 · Unincorporated Marin
Since October 2024 within ½ mile: 2 homes completed, 5 permitted, 3 proposed or in review.
10 projects with a record in this window, grouped by us from permits and State housing reports. Units are as proposed on each project's latest record and counted at its current stage.
149 permits within ½ mile since October 2024
The map shows new construction, ADUs, demolitions, additions, and renovations. Routine systems work (roofs, HVAC, water heaters) is counted but not mapped. Unit counts are as stated on permits.
$2,566,000
Benchmark range: $2,258,000 – $2,874,000
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Geography: permits located by parcel, ½ mile radius · Retrieved Oct 30, 2026
Public-records benchmark estimate combining Zillow Home Value Index (Data provided by Zillow), Census ACS 5-year estimates, parcel land-use/lot characteristics, and issued building permits. Not an official appraisal.
Permit counts, by the date issued (or applied, if not yet issued). Lot splits are planning cases, which we don't have.
We read public zoning and hazard maps against state law (ADUs: Gov. Code 66314; SB 9: Gov. Code 65852.21 and 66411.7). Local rules, title, tenancy history and site conditions can change the answer. Check with Unincorporated Marin's planning department before relying on it.
Sources: County of Marin GIS (MarinMap), Zoning (11 cities and unincorporated Marin) (retrieved Oct 30, 2026) · CAL FIRE Office of the State Fire Marshal, Fire Hazard Severity Zones in the State Responsibility Area (effective 2024-04-01) (retrieved Oct 26, 2026) · CAL FIRE Office of the State Fire Marshal, Fire Hazard Severity Zones in the Local Responsibility Area (map dated 2025-03-24) (retrieved Oct 26, 2026) · FEMA, National Flood Hazard Layer — flood hazard zones (retrieved Oct 26, 2026) · FEMA, National Flood Hazard Layer — FIRM panels (retrieved Oct 26, 2026) · California Geological Survey, Alquist-Priolo Earthquake Fault Zones (retrieved Oct 26, 2026) · Zoning classes: our classification of RA-B2 as single-family residential, checked against the zone description on Oct 24, 2026
Chronological history of building permit applications and issuances, snapshot-dated status changes, State housing entitlements, surrounding development within ½ mile, and area home-value trends.
Permit issued and active for 2.3 yr (first record Jul 5, 2024), with no completion or new permit record in 22 mo. · 1 unit · $2,800,000 declared valuation
Permit issued and active for 2.3 yr (first record Jul 23, 2024), with no completion or new permit record in 22 mo. · 1 unit · $500,000 declared valuation
Permit issued and active for 12.6 yr (first record Mar 13, 2014), with no completion or new permit record in 12.6 yr. · $6,450 declared valuation
Permit issued and active for 12.9 yr (first record Dec 19, 2013), with no completion or new permit record in 12.5 yr. · 1 unit · $445,000 declared valuation
Permit issued and active for 12.6 yr (first record Mar 6, 2014), with no completion or new permit record in 12.3 yr. · 1 unit · $174,000 declared valuation
Permit issued and active for 12.3 yr (first record Jun 30, 2014), with no completion or new permit record in 12.2 yr. · 1 unit · $685,000 declared valuation
54 Shell Rd · 1 unit · $182,160 valuation
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
Latest published Zillow Home Value Index (ZHVI) update
Changed from $1,980,059 in September 2025 to $2,181,389 in September 2026.
Source: Zillow Home Value Index (ZHVI) · Data provided by Zillow · Geography: ZIP 94941 (not a parcel appraisal)
29 Meadow Dr · 1 unit · $3,000 valuation
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
Pool / spa permit issued (181119)
Recorded status: Issued
Pool With Spa · Declared valuation: $75,000 · Contractor: Owner/Builder
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Geography: parcel
13 Shell Rd · 1 unit · $100,000 valuation
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
12 Shell Rd (A D U 12 A) · 1 unit · $8,000 valuation
Records span Mar 3, 2023 to Oct 15, 2025 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
Annual ZIP 94941 home-value index checkpoint
Changed from $2,042,452 in September 2024 to $1,980,059 in September 2025.
Source: Zillow Home Value Index (ZHVI) · Data provided by Zillow · Geography: ZIP 94941 (not a parcel appraisal)
1 unit
Records span Mar 4, 2024 to Sep 16, 2025 (0 permits).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
16 Shell Rd ( Adu 16a) · 1 unit · $300,000 valuation
Records span Mar 7, 2025 to Jul 17, 2025 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
Pool / spa permit application filed (181119)
Current status: Issued
Pool With Spa · Declared valuation: $75,000 · Contractor: Owner/Builder
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Geography: parcel
55 Plaza Dr (Adu 55a) · 1 unit · $790,000 valuation
Records span Apr 17, 2024 to Apr 3, 2025 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
Building permit reported to State HCD for 1 housing unit (P4380)
Reported in 2025 Housing Element Annual Progress Report
ADU · Renter
Source: California HCD, Housing Element Annual Progress Report — Table A2 · Geography: parcel
Building permit reported to State HCD for 1 housing unit (P4381)
Reported in 2025 Housing Element Annual Progress Report
SFD · Owner
Source: California HCD, Housing Element Annual Progress Report — Table A2 · Geography: parcel
Building permit reported to State HCD for 1 housing unit (178386)
Reported in 2025 Housing Element Annual Progress Report
SFD · Owner
Source: California HCD, Housing Element Annual Progress Report — Table A2 · Geography: parcel
Cross-referenced intelligence from our historical development graph—connecting parcels, permits, entity-resolved builders, empirical review-time distributions, and neighborhood renovation trends.
Explore full Unincorporated Marin development graph →Active in "Issued" for 2.3 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).
Active in "Issued" for 2.3 yr (first record Jul 23, 2024) with no new permit activity recorded in 22 mo.
Active in "Issued" for 2.5 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).
Active in "Applied" for 6.2 yr (first record Sep 1, 2020) with no new permit activity recorded in 6.2 yr. High-impact scale (1 housing unit, $1,000,000 declared valuation across 1 permit).
Active in "Applied" for 2.7 yr (first record Mar 4, 2024) with no new permit activity recorded in 2.7 yr.
Active in "Issued" for 12.3 yr (first record Jun 30, 2014) with no new permit activity recorded in 12.2 yr.
HUD Small Area Fair Market Rent · ZIP 94941
HUD FY 2026 · 40th-percentile gross rentCensus ACS 5-year median gross rent (all bedroom counts combined):
Area home-value benchmarks (not an appraisal)
ZIP & neighborhood mediansUnder California Proposition 13, the seller's historical assessed value does not carry over to a buyer. On sale, the parcel is reassessed at the purchase price: 1.00% base rate ($25,650/yr) + local voter-approved bond debt ($3,848/yr) + fixed direct levies/Mello-Roos ($450/yr).
Insurance & hazard context:
−$150,880/yr
Cash needed: $564,300
NOI: $4,760/yr
P&I: $12,970/mo
For $0/mo net cash flow
At $3,950/mo rent
| Scenario | Assumptions | Year 1 Rent | Year 1 Cash Flow | Cash-on-Cash | Break-Even Rent | Year 5 Cash Flow |
|---|---|---|---|---|---|---|
| Conservative | −8% starting rent, +3% vacancy, +3% combined maintenance/CapEx, 1.5%/yr rent growth | $3,634/mo | −$13,027/mo | -27.7% | $21,818/mo | −$13,087/mo |
| Base (your inputs) | Your entered assumptions, 3.0%/yr rent growth | $3,950/mo | −$12,573/mo | -26.7% | $20,195/mo | −$12,409/mo |
| Optimistic (cap-limited) | +6% starting rent, 3% vacancy, 4.5%/yr rent growth (capped by AB 1482 ceiling of 8.6%/yr) | $4,187/mo | −$12,313/mo | -26.2% | $19,726/mo | −$11,894/mo |
Rental regulatory context (informational only — not legal advice):
California AB 1482 (Tenant Protection Act, Civ. Code § 1947.12) caps annual rent increases at 5% + local CPI (max 10%) on covered properties.
Issued1 unitsJul 5, 2024 – Jan 3, 2025
Issued1 unitsJul 23, 2024 – Jan 3, 2025
We group related permits and State housing reports into projects. That grouping is our inference, not an official record.
Pool With Spa
Detached A D U
Demo (E) Structures; Build (N) S F D; Garage; Decks
Installation Of Temporary Power Pole
Replace Existing Tub W/ Walk-In; [N] 20a Circit For Tub
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Geography: parcel (APN) · Retrieved Oct 30, 2026 · Received and issued dates come from the County of Marin. The county publishes no final or expired status, so an issued permit stays 'Issued' after the work is done.
| Report year | Project / record | Type | Entitled | Permitted | Completed | Deed-restricted |
|---|---|---|---|---|---|---|
| 2025 | —(178386) | SFD · Owner | — | 1 (Jan 3, 2025) | — | — |
| 2025 | —(178387) | ADU · Renter | — | 1 (Jan 3, 2025) | — | — |
| 2025 | —(P4380) | ADU · Renter | — | 1 (Jan 3, 2025) | — | — |
| 2025 | —(P4381) | SFD · Owner | — | 1 (Jan 3, 2025) | — | — |
Source: California HCD, Housing Element Annual Progress Report — Table A2 · Geography: project (parcel) · Retrieved Oct 26, 2026 · From Unincorporated Marin's Housing Element Annual Progress Reports. A project can appear in several report years as it moves from entitlement to permit to completion.
Source: County of Marin GIS (MarinMap), Zoning (11 cities and unincorporated Marin) · Geography: zoning district polygon at parcel point · Retrieved Oct 30, 2026
0.47 acres
Assessor's classification for assessment purposes. This is not zoning.
30A SHELL RD; 30 SHELL RD
Source: County of Marin GIS (MarinMap), Parcels · Geography: parcel · Retrieved Oct 30, 2026
Search by parcel number 033-071-42. Assessed value is not market value.
Search by parcel number 033-071-42 (Marin County Tax Collector)
Permits issued in unincorporated Marin in the past 48 months. Each city keeps its own records.
The official flood hazard map for this location. Our reading of it is under What could be built here.
This site does not show owner names.