· Bel Marin Keys · APN 157-550-23 · Unincorporated Marin
Zoned RSP-1.6-BFC in Unincorporated Marin with likely ministerial ADU eligibility and mapped FEMA AE flood due diligence; benchmark value $1,615,000 ($1,373,000–$1,857,000).
Zone RSP-1.6-BFC allows residential use qualifying for ministerial ADU review under state law.
Source: Unincorporated Marin zoning · CA Gov. Code 66314
On-parcel permit history is indexed through Sep 13, 2017, letting you verify roof, HVAC, electrical, or structural work against seller disclosures.
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
Zone AE: 1% annual chance flood (Special Flood Hazard Area) overlaps this parcel. Expect mandatory flood insurance for federally backed loans and floodplain elevation/mitigation rules for new units or SB 9 applications.
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.
142 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.
$1,615,000
Benchmark range: $1,373,000 – $1,857,000
Closest lead: Demolition at 54 Calypso Shores (0.41 mi N, 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)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$1,585/mo). Confirm exact Mello-Roos / CFD special assessments on the county tax bill.
Source: CA Const. Art. XIIIA (Prop 13) · County Tax Collector
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Geography: permits located by parcel, ½ mile radius · Retrieved Nov 14, 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.
No ADU or new-home permits recorded within ¼ mile in this window.
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 14, 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-1.6-BFC 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 11.6 yr (first record Mar 25, 2015), with no completion or new permit record in 11.6 yr. · $4,860 declared valuation
Permit issued and active for 8.5 yr (first record May 21, 2018), with no completion or new permit record in 8.4 yr. · $50,000 declared valuation
In "Applied" for 4.5 yr (since May 26, 2022), with no new permit record in 4.5 yr. · $900 declared valuation
Permit issued and active for 4.6 yr (first record Mar 23, 2022), with no completion or new permit record in 4.4 yr. · 1 unit · $35,000 declared valuation
Permit issued and active for 3.5 yr (first record May 8, 2023), with no completion or new permit record in 2.4 yr. · 1 unit · $52,800 declared valuation
Nearby other (51 Del Oro Lagoon): First appeared in published agency feed
Record B49078 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby other (188 Caribe Isle): First appeared in published agency feed
Record B49032 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby plumbing / water heater / sewer (5 Bahama Reef): First appeared in published agency feed
Record B48989 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby windows / doors / siding (934 Bel Marin Keys Blvd): First appeared in published agency feed
Record B48879 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby other (15 Dolphin Isle): First appeared in published agency feed
Record B48945 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
116 Bahama Reef · 1 unit · $52,800 valuation
Records span May 8, 2023 to Jul 2, 2024 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
1108 Bel Marin Keys Blvd (Aka 1110) · 1 unit · $35,000 valuation
Records span Mar 23, 2022 to Jun 10, 2022 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
54 Calypso Shores · $900 valuation
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
120 Del Oro Lagoon A K A · 1 unit · $145,000 valuation
Records span Mar 19, 2020 to Feb 9, 2021 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
68 Del Oro Lagoon A K A · 1 unit · $75,000 valuation
Records span Dec 24, 2018 to Oct 23, 2019 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
1051 Bel Marin Keys Blvd · $50,000 valuation
Records span May 21, 2018 to Jun 19, 2018 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
184 Caribe Isle · 1 unit · $25,000 valuation
Records span Apr 24, 2017 to Jan 11, 2018 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
Other permit issued (156496)
Recorded status: Issued
Replace Backflow Prevention Valve · Declared valuation: $700 · Contractor: Ongaro, Ernest & Sons, Inc.
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Geography: parcel
18 Dolphin Isle · $4,860 valuation
Records span Mar 25, 2015 to Apr 23, 2015 (1 permit).
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 4.5 yr (since May 26, 2022), exceeding the 55d median and 261d 90th percentile for demolition permits in Unincorporated Marin (n=130).
Active in "Issued" for 11.6 yr (first record Mar 25, 2015) with no new permit activity recorded in 11.6 yr.
Active in "Issued" for 4.6 yr (first record Mar 23, 2022) with no new permit activity recorded in 4.4 yr.
Active in "Issued" for 8.5 yr (first record May 21, 2018) with no new permit activity recorded in 8.4 yr.
Active in "Issued" for 3.5 yr (first record May 8, 2023) with no new permit activity recorded in 2.4 yr.
Substantial improvements (additions, interior remodels, ADUs, commercial TI, and new builds) across 741 parcels
Small prior baseline
City baseline: 16.3 / 1k
7 in trailing 24m
Includes 0 ADUs
| Builder / contractor | Primary specialty | Here / ½ mi | ½ mi valuation | Citywide 24m trend |
|---|---|---|---|---|
| Ongaro Ernest And Sons | Other | 1 on parcel1 in ½ mi | $700 | 0 vs 0 prior |
| Owner Builder Recent nearby: 49 Calypso Shores (Feb 23, 2026) | Remodel / interior alteration | 27 in ½ mi | $991,300 | 226 vs 240 prior−6% |
| Owner Recent nearby: 2 Bahama Reef (Mar 2, 2022) | Remodel / interior alteration |
| Permit category | Sample (n) | 25th pct | Median (50th) | 75th pct | 90th pct | Recent 24m median |
|---|---|---|---|---|---|---|
| New single-family home | 121 | 166d | 253d | 456d | 686d | 210d(vs 276d 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 Metro Fair Market Rent · San Francisco, CA HUD Metro FMR Area
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 ($16,150/yr) + local voter-approved bond debt ($2,423/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.
−$86,882/yr
Cash needed: $355,300
NOI: $11,114/yr
P&I: $8,166/mo
For $0/mo net cash flow
At $3,600/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 | $3,312/mo | −$7,654/mo | -25.9% | $13,996/mo | −$7,664/mo |
| Base (your inputs) | Your entered assumptions, 3.0%/yr rent growth | $3,600/mo | −$7,240/mo | -24.5% | $12,954/mo | −$7,047/mo |
| Optimistic (cap-limited) | +6% starting rent, 3% vacancy, 4.5%/yr rent growth (capped by AB 1482 ceiling of 8.6%/yr) | $3,816/mo | −$7,003/mo | -23.7% | $12,653/mo | −$6,577/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.
Replace Backflow Prevention Valve
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Geography: parcel (APN) · Retrieved Nov 14, 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 14, 2026
0.31 acres
Assessor's classification for assessment purposes. This is not zoning.
Source: County of Marin GIS (MarinMap), Parcels · Geography: parcel · Retrieved Nov 14, 2026
Search by parcel number 157-550-23. Assessed value is not market value.
Search by parcel number 157-550-23 (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.
| 17 in ½ mi |
| $606,548 |
| 25 vs 15 prior+67% |
| Natal Modica Construction Recent nearby: 98 Del Oro Lagoon (Oct 2, 2018) | New garage / accessory structure | 3 in ½ mi | $318,000 | 0 vs 1 prior |
| Rafael Home Services Recent nearby: 99 Del Oro Lagoon (Mar 28, 2025) | Remodel / interior alteration | 2 in ½ mi | $650,000 | 0 vs 0 prior |
| Chase Home Improvements Recent nearby: 1097 Bel Marin Keys Blvd (Sep 3, 2024) | Remodel / interior alteration | 2 in ½ mi | $210,000 | 0 vs 0 prior |
| Marin Kitchen Works Merged: MARIN KITCHEN WORKS · MARIN KITCHEN WORKS INC Recent nearby: 101 Bahama Reef (Sep 18, 2024) | Remodel / interior alteration | 2 in ½ mi | $210,000 | 0 vs 2 prior |
| Ron Davis Recent nearby: 18 Dolphin Isle (Jul 8, 2015) | Demolition | 2 in ½ mi | $39,860 | 0 vs 0 prior |
| Caruso Construction Recent nearby: 176 Del Oro Lagoon (Oct 27, 2022) | Addition (adds square footage) | 1 in ½ mi | $990,000 | 0 vs 0 prior |
| Tech Home Recent nearby: 104 Bahama Reef (Oct 12, 2020) | Remodel / interior alteration | 1 in ½ mi | $692,000 | 0 vs 0 prior |
| 316 |
| 103d |
| 160d |
| 249d |
| 440d |
| 159d(vs 166d 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) |
| OtherOn this parcel | 1,562 | 0d | 0d | 1d | 71d | 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.