San Rafael 94903 · Lucas Valley · APN 164-422-27 · Unincorporated Marin
Zoned R1-B-LV in Unincorporated Marin with likely ADU & SB 9 infill eligibility and mapped CAL FIRE high fire hazard severity zone (local responsibility area) due diligence; benchmark value $1,406,000 ($1,237,000–$1,575,000).
Zoned R1-B-LV supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 9,322 sq ft lot. Local precedent is active with 1 ADU permit 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 (3 total permits, latest May 19, 2025).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
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)
Automated synthesis of indexed municipal, county, state, and federal public records — informational context only, not a formal appraisal, survey, or legal/tax determination.
Since November 2024 within ½ mile: 2 permitted, 1 proposed or in review; 1 demolition.
4 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.
166 permits within ½ mile since November 2024
$1,406,000
Benchmark range: $1,237,000 – $1,575,000
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 Mar 24, 2025)
Closest lead: New home (0.23 mi SE, 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)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$1,385/mo). Confirm exact Mello-Roos / CFD special assessments on the county tax bill.
Source: CA Const. Art. XIIIA (Prop 13) · County Tax Collector
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 R1-B-LV 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.
In "Entitled" for 5.1 yr (since Sep 23, 2021), with no new permit record in 5.1 yr. · 1 unit
In "Entitled" for 3.8 yr (since Jan 14, 2023), with no new permit record in 3.8 yr. · 1 unit
In "Entitled" for 3.3 yr (since Jul 10, 2023), with no new permit record in 3.3 yr. · 1 unit
Permit issued and active for 3.2 yr (first record Aug 14, 2023), with no completion or new permit record in 3.2 yr. · 1 unit
In "Entitled" for 2.9 yr (since Dec 7, 2023), with no new permit record in 2.9 yr. · 1 unit
Permit issued and active for 3.1 yr (first record Oct 20, 2023), with no completion or new permit record in 2.4 yr. · 1 unit · $146,600 declared valuation
Nearby roof replacement (1125 Idylberry Rd): First appeared in published agency feed
Record B49056 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby other (55 Pikes Peak Dr): First appeared in published agency feed
Record B49039 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby other (913 Appleberry Dr): First appeared in published agency feed
Record B49034 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby roof replacement (1 Mt Palomar Ct): First appeared in published agency feed
Record B48964 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby remodel / interior alteration (1129 Idylberry Rd): First appeared in published agency feed
Record 94620 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby other (125 Mt Lassen Dr): First appeared in published agency feed
Record B48900 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby roof replacement (3 Mt Darwin Ct): First appeared in published agency feed
Record B48883 · 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 $1,200,587 in September 2025 to $1,250,063 in September 2026.
Source: Zillow Home Value Index (ZHVI) · Data provided by Zillow · Geography: ZIP 94903 (not a parcel appraisal)
90 Mt Lassen Dr · $400 valuation
Records span Dec 8, 2025 to Jan 8, 2026 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
125 Mt Lassen Dr (Adu 125a) · 1 unit · $56,500 valuation
Records span Dec 11, 2024 to Nov 19, 2025 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
Annual ZIP 94903 home-value index checkpoint
Changed from $1,237,445 in September 2024 to $1,200,587 in September 2025.
Source: Zillow Home Value Index (ZHVI) · Data provided by Zillow · Geography: ZIP 94903 (not a parcel appraisal)
1 unit
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
Roof replacement permit application filed (B42442)
Current status: Issued
Apply polyurethane foam roof overlay over entire roof. — ReRoofing · Declared valuation: $20,000 · Contractor: Abril Roofing Inc
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Geography: parcel
Roof replacement permit issued (B42442)
Recorded status: Issued
Apply polyurethane foam roof overlay over entire roof. — ReRoofing · Declared valuation: $20,000 · Contractor: Abril Roofing Inc
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Geography: parcel
2 Mt Wittenburg Ct (Adu 2a) · 1 unit · $125,000 valuation
Records span May 29, 2024 to Feb 11, 2025 (2 permits).
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 "Entitled" for 2.9 yr (since Dec 7, 2023), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
In "Entitled" for 3.3 yr (since Jul 10, 2023), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
In "Entitled" for 3.8 yr (since Jan 14, 2023), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
In "Entitled" for 5.1 yr (since Sep 23, 2021), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
Active in "Issued" for 3.2 yr (first record Aug 14, 2023) with no new permit activity recorded in 3.2 yr.
Active in "Issued" for 3.1 yr (first record Oct 20, 2023) with no new permit activity recorded in 2.4 yr.
Substantial improvements (additions, interior remodels, ADUs, commercial TI, and new builds) across 768 parcels
Small prior baseline
City baseline: 16.4 / 1k
10 in trailing 24m
Includes 3 ADUs
| Builder / contractor | Primary specialty | Here / ½ mi | ½ mi valuation | Citywide 24m trend |
|---|---|---|---|---|
| Abril Roofing | Roof replacement | 2 on parcel2 in ½ mi | $45,000 | 0 vs 0 prior |
| Senga Energy | Solar / battery storage | 1 on parcel1 in ½ mi | $27,409 | 0 vs 0 prior |
| Owner Builder Recent nearby: 90 Mt Lassen Dr (Jan 8, 2026) | Remodel / interior alteration | 20 in ½ mi | $2,541,256 |
| 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 94903
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 ($14,050/yr) + local voter-approved bond debt ($2,108/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.
−$66,383/yr
Cash needed: $309,100
NOI: $18,870/yr
P&I: $7,104/mo
For $0/mo net cash flow
At $4,175/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 | $3,841/mo | −$6,012/mo | -23.3% | $12,233/mo | −$5,982/mo |
| Base (your inputs) | Your entered assumptions, 3.0%/yr rent growth | $4,175/mo | −$5,532/mo | -21.5% | $11,322/mo | −$5,266/mo |
| Optimistic (cap-limited) | +6% starting rent, 3% vacancy, 4.5%/yr rent growth (capped by AB 1482 ceiling of 8.6%/yr) | $4,426/mo | −$5,256/mo | -20.4% | $11,059/mo | −$4,721/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.
Apply polyurethane foam roof overlay over entire roof. — ReRoofing
Apply polyurethane foam roof overlay — ReRoofing
7.82kw Rooftop Photovoltaic - Express
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
0.21 acres
Assessor's classification for assessment purposes. This is not zoning.
4 MT DIABLO CIR
Source: County of Marin GIS (MarinMap), Parcels · Geography: parcel · Retrieved Nov 13, 2026
Search by parcel number 164-422-27. Assessed value is not market value.
Search by parcel number 164-422-27 (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.
| Tim Lawlor Construction Recent nearby: 25 Mt Lassen Dr (Jul 24, 2024) | Remodel / interior alteration | 6 in ½ mi | $695,000 | 0 vs 1 prior |
| Marin Kitchen Works Merged: MARIN KITCHEN WORKS · MARIN KITCHEN WORKS INC Recent nearby: 1220 Idylberry Rd (Mar 15, 2024) | Addition (adds square footage) | 5 in ½ mi | $455,000 | 0 vs 2 prior |
| Loic Humbert Recent nearby: 7 Mt Lassen Dr #A (Sep 20, 2016) | Remodel / interior alteration | 4 in ½ mi | $98,000 | 0 vs 0 prior |
| Schalich Brothers Construction Recent nearby: 82 Mt Muir Ct (Mar 5, 2018) | Remodel / interior alteration | 3 in ½ mi | $127,000 | 7 vs 1 prior |
| Sykches Recent nearby: 15 Mt Muir Ct (Aug 4, 2020) | Remodel / interior alteration | 3 in ½ mi | $116,500 | 0 vs 0 prior |
| Swan Pools Recent nearby: 910 Idylberry Rd (Mar 10, 2022) | Pool / spa | 3 in ½ mi | $103,000 | 1 vs 4 prior |
| Owner Recent nearby: 1154 Idylberry Rd (Jul 12, 2021) | Remodel / interior alteration | 3 in ½ mi | $46,000 | 25 vs 15 prior+67% |
| 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.