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ActiveSingle Family

$7,888,000

685 Riviera Dr, Los Altos 94024

Beds6
Baths6
Sqft4,140
DOM1
No Photos Available

Size check

The listing's square footage against the county assessor's record and the permits on file.

Listing
4,140 sqft
County record
4,140 sqft
Difference
+0 (+0%)

The listing and the county record agree within 10%.

What can explain a difference
  • Space built without a permit.
  • Permitted work the assessor has not recorded yet.
  • An ADU, a finished basement or a converted garage counted in one figure and not the other.
  • Different measuring. Listing agents and the assessor often measure the same house differently.
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AddressIntel AI Briefing

The optimal play is stealth density by adding high-end ADUs to the existing estate while keeping the massive 4,140 square foot primary home. A teardown is highly unfeasible given the updated interior and already high purchase price relative to size-matched resale values. This strategy unlocks maximum yield on a clean lot with zero environmental hazards.

Property Permit History

No permit history found directly associated with this property's address.

Recent Neighborhood Remodeling (Los Altos)

Parcel & Zoning Info

APN18936043
Official Lot Sqft11,326
Zoning Code--
SB 9 StatusLikely · up to 4 units
Unlock Pathways
Ministerial ADU Ministerial SB 9 Density Bonus
Entitlement RiskLow (0/100)

ADU Potential

Feasibility Score88/100
Max ADU Units2 (ADU + JADU)
Est. ADU Size1,200 sqft
Existing Coverage36.6%

Deep lot · Corner lot · ~81 ft frontage × 149 ft deep, room to set a detached ADU back from the street with a buffer, reads as a separate home. A second street frontage lets an ADU take its own entrance and address.

Screening heuristic based on lot size, existing coverage, lot orientation, and hazard overlays. CA ADU law is ministerial statewide; verify max size, setbacks, and JADU owner-occupancy with the local planning dept.

Redevelopment Potential

Redevelopment Score15/100
ClassBuilt out
FAR Utilization107% of allowed
Buildable Headroom+0 sqft

Existing home already uses most of the allowable floor area, little expansion headroom. Zoning allows roughly 3,883 sqft of gross floor area on this lot.

Screening estimate comparing existing living area to the city's single-family floor-area limit. FAR rule curated from current municipal code. Source: Los Altos Muni Code 14.06.070/14.08.070/14.10.070/14.12.070 (R1-10/H/20/40, one shared formula) (as of 2026-08-24). Verify FAR, coverage, setbacks, and height with the local planning dept.

Hazard Snapshot

Flood Zone

X
Area of minimal flood hazard.

Fire Severity

None
Not in a mapped state fire severity zone.

Liquefaction

No
Not in a mapped liquefaction zone.

Fault Zone

No
Not in a mapped Alquist-Priolo fault zone.

Not a substitute for a Natural Hazard Disclosure (NHD) report. Zones reflect available GIS data and may not cover all localities. Liquefaction and fault flags: modified from California Geological Survey, Web Service of Official Maps of Alquist-Priolo Earthquake Fault Zones and Web Service of Official Maps of Seismic Hazard Zones (2025).

Nearby Public Schools

Elementary School

Almond Elementary

Los Altos Elementary

0.4 miles away
Middle School

Isaac Newton Graham Middle

Mountain View Whisman

0.7 miles away
High School

Los Altos High

Mountain View-Los Altos Union High

0.8 miles away

School boundaries are subject to change. Nearest school distance does not guarantee enrollment eligibility. Check with the local district. Data provided by CDE.

Proprietary Intelligence

Market Heat Index

70/100

Based on recent sales velocity and local demand in 94024.

Flippability Score

15/100

Measures neighborhood renovation density vs. recent permits on this property.

Bidding War Prob.

50%

Likelihood of multiple offers based on local list-to-sale ratios and DOM.

Proforma ROI Calculator

Back-of-the-napkin deal analysis across development strategies.

Zoning allows roughly 3,883 sqft here, less than the 4,140 sqft standing today, so a compliant rebuild would be smaller than the existing house. We don't quote a return on this one. Demolishing generally forfeits the existing non-conforming floor area, so treat it as a remodel or check the local code for what it lets you rebuild.

Median of 12 recent single-family sales in Los Altos (94024): $1,780/sqft, plus 5% because new houses sold at a median 1.07x their comps across 239 real rebuilds. Sized within 25% of the 4,100 sqft build, because smaller houses sell for more per foot and pricing a rebuild off them overstates resale.

Commission, transfer tax and closing. Deducted from resale before profit, so the ROI below is net of the exit rather than gross.

Interest on the purchase price for the whole project plus half the build budget, since construction draws ramp up. The default is 7% over 33 months, the median purchase-to-sale time of 239 real Peninsula and South Bay rebuilds. Set the rate to 0 for a cash purchase, or use your own lender's terms.

Hard Costs$2,145,000
New Build3,900 sqft
Total Capital Required$10,208,000
Estimated Resale (ARV)$7,289,100
Cost of Sale (5%)-$364,455
Carry (33mo @ 7%)-$1,741,740
Net Proceeds$5,182,905

Projected Profit

-$5,025,095
-49.2% ROI

Warning: Project is mathematically underwater.

Recent Comparables (Los Altos 94024)

Sized to the modelled 4,100 sqft build: sales within 25% of it. Smaller houses sell for more per foot, so pricing a rebuild off them overstates resale.

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