Mill Valley 94941 · Tamalpais · APN 200-173-20 · Unincorporated Marin
Zoned RSP-2 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and mapped CAL FIRE high fire hazard severity zone (state responsibility area) due diligence; benchmark value $2,214,000 ($1,948,000–$2,480,000).
Zoned RSP-2 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 10,193 sq ft lot. Local precedent is active with 5 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
Public building records show issued construction/renovation work on this parcel (7 total permits, latest Aug 25, 2023).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
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)
Automated synthesis of indexed municipal, county, state, and federal public records — informational context only, not a formal appraisal, survey, or legal/tax determination.
$2,214,000
Benchmark range: $1,948,000 – $2,480,000
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)
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)
Solar / battery storage (166083): Issued after 2 mo — slower than 90% of solar / battery storage permits in Unincorporated Marin (median 0d, 90th pct 2d, n=2,977).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (review-time benchmark)
Closest lead: New home at 560 Alta Way (0.27 mi E, 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)
Since November 2024 within ½ mile: 1 homes completed, 5 permitted, 4 proposed or in review; 1 demolition.
11 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.
365 permits within ½ mile since November 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.
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Geography: permits located by parcel, ½ mile radius · Retrieved Nov 13, 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 Nov 13, 2026) · CAL FIRE Office of the State Fire Marshal, Fire Hazard Severity Zones in the State Responsibility Area (effective 2024-04-01) (retrieved Nov 9, 2026) · CAL FIRE Office of the State Fire Marshal, Fire Hazard Severity Zones in the Local Responsibility Area (map dated 2025-03-24) (retrieved Nov 9, 2026) · FEMA, National Flood Hazard Layer — flood hazard zones (retrieved Nov 9, 2026) · FEMA, National Flood Hazard Layer — FIRM panels (retrieved Nov 9, 2026) · California Geological Survey, Alquist-Priolo Earthquake Fault Zones (retrieved Nov 9, 2026) · Zoning classes: our classification of RSP-2 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 12.4 yr (first record Jun 2, 2014), with no completion or new permit record in 12.4 yr. · $400 declared valuation
Permit issued and active for 12.4 yr (first record Jun 10, 2014), with no completion or new permit record in 12.3 yr. · $12,500 declared valuation
Permit issued and active for 12.1 yr (first record Sep 29, 2014), with no completion or new permit record in 11.3 yr. · 1 unit · $600,000 declared valuation
Permit issued and active for 10.2 yr (first record Aug 15, 2016), with no completion or new permit record in 9.9 yr. · 1 unit · $900,000 declared valuation
Permit issued and active for 7.5 yr (first record May 14, 2019), with no completion or new permit record in 7.5 yr. · $10,000 declared valuation
Permit issued and active for 6.8 yr (first record Feb 11, 2020), with no completion or new permit record in 6.8 yr. · $39,972 declared valuation
Nearby other (529 Brookline Way): First appeared in published agency feed
Record B49083 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby other (1075 Erica Rd): First appeared in published agency feed
Record B49072 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby other (1217 Waterview Dr): First appeared in published agency feed
Record 94643 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby other (908 Vernal Way): First appeared in published agency feed
Record B49065 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby other (1212 El Cide Ct): First appeared in published agency feed
Record B49060 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby other (552 Shoreline Hwy): First appeared in published agency feed
Record B48968 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby windows / doors / siding (875 Chamberlain Ct): First appeared in published agency feed
Record B48958 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby roof replacement (546 Fairview Ave): First appeared in published agency feed
Record B48831 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff 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)
543 Northern Ave · 1 unit · $188,000 valuation
Records span Dec 30, 2025 to Jun 17, 2026 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
916 Valley View Ln · 1 unit · $5,000 valuation
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
81 Skyline Ter · 1 unit · $85,000 valuation
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
522 Northern Ave (A D U 523 Shasta Ave) · 1 unit · $150,000 valuation
Records span Sep 3, 2025 to Apr 16, 2026 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
526 Alta Way · 1 unit · $550,000 valuation
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
812 Chamberlain Ct · 1 unit
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
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 →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).
Issued after 2 mo — slower than 90% of solar / battery storage permits in Unincorporated Marin (median 0d, 90th pct 2d, n=2,977).
Active in "Issued" for 10.2 yr (first record Aug 15, 2016) with no new permit activity recorded in 9.9 yr. High-impact scale (1 housing unit, $900,000 declared valuation across 1 permit).
In "Entitled" for 4.8 yr (since Jan 19, 2022), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
In "Applied" for 2.6 yr (since Apr 8, 2024), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
In "Entitled" for 5.6 yr (since Apr 5, 2021), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
Substantial improvements (additions, interior remodels, ADUs, commercial TI, and new builds) across 2,439 parcels
−7.7% YoY
City baseline: 16.4 / 1k
50 in trailing 24m
Includes 16 ADUs
| Builder / contractor | Primary specialty | Here / ½ mi | ½ mi valuation | Citywide 24m trend |
|---|---|---|---|---|
| Owner Builder | Remodel / interior alteration | 1 on parcel52 in ½ mi | $4,763,282 | 226 vs 240 prior−6% |
| Owner | Remodel / interior alteration | 4 on parcel31 in ½ mi | $1,722,900 | 25 vs 15 prior+67% |
| Sun Metrics | Solar / battery storage | 1 on parcel |
| Permit category | Sample (n) | 25th pct | Median (50th) | 75th pct | 90th pct | Recent 24m median |
|---|---|---|---|---|---|---|
| New single-family home | 121 | 166d | 253d | 456d | 686d | 211d(vs 273d prior) |
| New multifamily / condos / mixed-use | 21 | 272d | 292d | 293d | 313d | 293d(vs 197d prior) |
| Accessory dwelling unit (new or conversion) | 298 | 120d | 204d | 331d | 549d | 214d(vs 181d prior) |
| Addition (adds square footage) |
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 ($22,150/yr) + local voter-approved bond debt ($3,323/yr) + fixed direct levies/Mello-Roos ($450/yr).
Mapped hazard zone insurance context on this parcel:
Model adding a backyard ADU or garage conversion under California's Prop 13 blended new-construction assessment (existing house & land tax base stays intact; only ADU build cost is assessed) and SB 13 impact-fee rules.
−$126,938/yr
Cash needed: $487,300
NOI: $7,465/yr
P&I: $11,200/mo
For $0/mo net cash flow
At $3,950/mo gross 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 | −$11,032/mo | -27.2% | $19,033/mo | −$11,076/mo |
| Base (your inputs) | Your entered assumptions, 3.0%/yr rent growth | $3,950/mo | −$10,578/mo | -26.0% | $17,617/mo | −$10,398/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 | −$10,318/mo | -25.4% | $17,208/mo | −$9,882/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.
16 kWh BESS
3.87 kW rooftop PV system
Replace existing furnace and duct work. — New Ductwork, Replace Ductwork, Replace Mechanical Appliance
4.8kw Roof Photovoltaic & Energy Storage - Express
Addtn, Deck, Plumb
Tear Off and Reroof — ReRoofing
Repl 2 Skylights Size For Size - Express ***Expired
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Geography: parcel (APN) · Retrieved Nov 13, 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.
No housing activity reported to the State for this parcel (2018–2025 reports).
Source: California HCD, Housing Element Annual Progress Report — Table A2 · Geography: project (parcel) · Retrieved Nov 9, 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 Nov 13, 2026
0.23 acres
Assessor's classification for assessment purposes. This is not zoning.
1003 TRILLIUM LN
Source: County of Marin GIS (MarinMap), Parcels · Geography: parcel · Retrieved Nov 13, 2026
Search by parcel number 200-173-20. Assessed value is not market value.
Search by parcel number 200-173-20 (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.
| $23,000 |
| 0 vs 0 prior |
| Grc Roofing | Roof replacement | 1 on parcel1 in ½ mi | $9,400 | 0 vs 0 prior |
| Yonts Construction Recent nearby: 549 Browning St (Jul 19, 2023) | Remodel / interior alteration | 5 in ½ mi | $563,500 | 1 vs 1 prior |
| Barton Design And Constuction Recent nearby: 1201 Waterview Dr (Jun 4, 2018) | Remodel / interior alteration | 3 in ½ mi | $840,000 | 0 vs 0 prior |
| Gannon Construction Recent nearby: 969 W California Ave (Sep 16, 2026) | Remodel / interior alteration | 3 in ½ mi | $600,000 | 4 vs 4 prior |
| G Family Construction Recent nearby: 541 Marin Ave (Oct 28, 2021) | Remodel / interior alteration | 3 in ½ mi | $395,000 | 0 vs 0 prior |
| Lamperti Contracting And Design Recent nearby: 1125 W California Ave (Feb 1, 2024) | Remodel / interior alteration | 3 in ½ mi | $344,716 | 2 vs 7 prior |
| I Construction And Structural Merged: I CONSTRUCTION AND STRUCTURAL INC · I CONSTRUCTION & STRUCTURAL INC Recent nearby: 543 Northern Ave (Jun 17, 2026) | Accessory dwelling unit (new or conversion) | 3 in ½ mi | $308,000 | 0 vs 1 prior |
| 316 |
| 103d |
| 160d |
| 249d |
| 440d |
| 157d(vs 167d prior) |
| Remodel / interior alteration | 1,054 | 36d | 83d | 148d | 266d | 112d(vs 77d prior) |
| Commercial tenant improvement | 81 | 99d | 148d | 233d | 443d | 152d(vs 150d prior) |
| Solar / battery storageOn this parcel | 2,977 | 0d | 0d | 0d | 2d | 0d |
| Roof replacementOn this parcel | 3,663 | 0d | 0d | 0d | 0d | 0d |
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Computed from issued permits with recorded application and issuance dates over the trailing 60 months. Categories with fewer than 20 permits are excluded.