Diablo 94528 · APN 195-340-029-6 · Unincorporated Contra Costa
Since — within ½ mile: 3 homes completed, 1 permitted, 1 proposed or in review.
5 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.
No permit activity recorded within ½ mile.
$3,462,000
Benchmark range: $2,943,000 – $3,981,000
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.
We don't have building permits for Unincorporated Contra Costa, so we can't show what has been permitted nearby.
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 Contra Costa's planning department before relying on it.
Sources: Contra Costa County Department of Conservation and Development, Zoning (unincorporated Contra Costa) (retrieved Oct 26, 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 R-40 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 3.9 yr (since Dec 14, 2022), with no new permit record in 3.9 yr. · 1 unit
In "Entitled" for 7.5 yr (since May 6, 2019), with no new permit record in 7.5 yr. · 2 units
Permit issued and active for 6.4 yr (first record Jun 23, 2020), with no completion or new permit record in 6.4 yr. · 1 unit
Permit issued and active for 5.9 yr (first record Nov 23, 2020), with no completion or new permit record in 5.9 yr. · 1 unit
Permit issued and active for 4.9 yr (first record Dec 6, 2021), with no completion or new permit record in 4.9 yr. · 1 unit
Permit issued and active for 4.5 yr (first record May 12, 2022), with no completion or new permit record in 4.5 yr. · 1 unit
Latest published Zillow Home Value Index (ZHVI) update
Changed from $2,989,232 in September 2025 to $3,107,080 in September 2026.
Source: Zillow Home Value Index (ZHVI) · Data provided by Zillow · Geography: ZIP 94528 (not a parcel appraisal)
Source: City of Richmond Planning & Building, PermitTrak (eTRAKiT permits, 1992 to April 2025) & HCD APR (grouped project within ½ mile)
Source: City of Richmond Planning & Building, PermitTrak (eTRAKiT permits, 1992 to April 2025) & HCD APR (grouped project within ½ mile)
Source: City of Richmond Planning & Building, PermitTrak (eTRAKiT permits, 1992 to April 2025) & HCD APR (grouped project within ½ mile)
Annual ZIP 94528 home-value index checkpoint
Changed from $3,136,064 in September 2024 to $2,989,232 in September 2025.
Source: Zillow Home Value Index (ZHVI) · Data provided by Zillow · Geography: ZIP 94528 (not a parcel appraisal)
1 unit
Source: City of Richmond Planning & Building, PermitTrak (eTRAKiT permits, 1992 to April 2025) & HCD APR (grouped project within ½ mile)
1 unit
Source: City of Richmond Planning & Building, PermitTrak (eTRAKiT permits, 1992 to April 2025) & HCD APR (grouped project within ½ mile)
Annual ZIP 94528 home-value index checkpoint
Changed from $3,146,882 in September 2023 to $3,136,064 in September 2024.
Source: Zillow Home Value Index (ZHVI) · Data provided by Zillow · Geography: ZIP 94528 (not a parcel appraisal)
1 unit
Source: City of Richmond Planning & Building, PermitTrak (eTRAKiT permits, 1992 to April 2025) & HCD APR (grouped project within ½ mile)
Source: City of Richmond Planning & Building, PermitTrak (eTRAKiT permits, 1992 to April 2025) & HCD APR (grouped project within ½ mile)
1 unit
Source: City of Richmond Planning & Building, PermitTrak (eTRAKiT permits, 1992 to April 2025) & HCD APR (grouped project within ½ mile)
Source: City of Richmond Planning & Building, PermitTrak (eTRAKiT permits, 1992 to April 2025) & HCD APR (grouped project within ½ mile)
1 unit
Source: City of Richmond Planning & Building, PermitTrak (eTRAKiT permits, 1992 to April 2025) & HCD APR (grouped project within ½ mile)
Annual ZIP 94528 home-value index checkpoint
Changed from $3,250,410 in September 2022 to $3,146,882 in September 2023.
Source: Zillow Home Value Index (ZHVI) · Data provided by Zillow · Geography: ZIP 94528 (not a parcel appraisal)
1 unit
Source: City of Richmond Planning & Building, PermitTrak (eTRAKiT permits, 1992 to April 2025) & 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 Contra Costa development graph →Active in "Entitled" for 3.9 yr (first record Dec 14, 2022) with no new permit activity recorded in 3.9 yr.
Active in "Issued" for 2.2 yr (first record Aug 1, 2024) with no new permit activity recorded in 2.2 yr.
Active in "Entitled" for 3.3 yr (first record Jul 24, 2023) with no new permit activity recorded in 3.3 yr.
Active in "Issued" for 4.1 yr (first record Oct 6, 2022) with no new permit activity recorded in 4.1 yr.
Active in "Issued" for 4.1 yr (first record Oct 6, 2022) with no new permit activity recorded in 4.1 yr.
Active in "Entitled" for 4.1 yr (first record Oct 6, 2022) with no new permit activity recorded in 4.1 yr.
HUD Small Area Fair Market Rent · ZIP 94528
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 ($34,600/yr) + local voter-approved bond debt ($6,228/yr) + fixed direct levies/Mello-Roos ($450/yr).
Mapped hazard zone insurance context on this parcel:
−$226,894/yr
Cash needed: $761,200
NOI: -$16,946/yr
P&I: $17,496/mo
For $0/mo net cash flow
At $2,975/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 | $2,737/mo | −$19,250/mo | -30.3% | $29,607/mo | −$19,438/mo |
| Base (your inputs) | Your entered assumptions, 3.0%/yr rent growth | $2,975/mo | −$18,908/mo | -29.8% | $27,404/mo | −$18,928/mo |
| Optimistic (cap-limited) | +6% starting rent, 3% vacancy, 4.5%/yr rent growth (capped by AB 1482 ceiling of 8.6%/yr) | $3,154/mo | −$18,711/mo | -29.5% | $26,767/mo | −$18,539/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.
Entitled1 unitsDec 14, 2022 – Dec 14, 2022
We group related permits and State housing reports into projects. That grouping is our inference, not an official record.
No building permits are recorded for this parcel since 2016.
Source: City of Richmond Planning & Building, PermitTrak (eTRAKiT permits, 1992 to April 2025) · Geography: parcel (APN) · Retrieved Oct 26, 2026 · Richmond's permits come from its eTRAKiT system, retired in 2025. Statuses are as of April 2025, and later permits are not published.
| Report year | Project / record | Type | Entitled | Permitted | Completed | Deed-restricted |
|---|---|---|---|---|---|---|
| 2024 | —(CDSU22-00121) | ADU · Renter | 1 (Dec 14, 2022) | — | — | — |
| 2023 | —(CDSU22-00121) | ADU · Renter | 1 (Dec 14, 2022) | — | — | — |
| 2022 | —(CDSU22-00121) | ADU · Renter | 1 (Dec 14, 2022) | — | — | — |
Source: California HCD, Housing Element Annual Progress Report — Table A2 · Geography: project (parcel) · Retrieved Oct 26, 2026 · From Unincorporated Contra Costa's Housing Element Annual Progress Reports. A project can appear in several report years as it moves from entitlement to permit to completion.
Source: Contra Costa County Department of Conservation and Development, Zoning (unincorporated Contra Costa) · Geography: zoning district polygon at parcel point · Retrieved Oct 26, 2026
1.11 acres
Assessor's classification for assessment purposes. This is not zoning.
21 BELLA VISTA
Source: Contra Costa County Assessor / Department of Information Technology, Assessment Parcels · Geography: parcel · Retrieved Oct 26, 2026
County map with assessor parcel maps and zoning. Search parcel 195-340-029.
Search by parcel number 195-340-029 (Contra Costa County Treasurer-Tax Collector). Assessed value is not market value.
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.