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Activesingle_family

$5,595,000

9 Bel Aire Ln, San Mateo 94402

Beds4
Baths4.5
Sqft3,908
DOM134
No Photos Available

AddressIntel AI Briefing

Overpriced estate with active landslide hazard risks that will drive up engineering and foundation costs. Clearly a retail play with no developmental upside.

Property Permit History

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

Recent Neighborhood Remodeling (San Mateo)

2026-10-20 • 308 42ND AVE SAN MATEO CA 94403-5004
Single Family (Addition) - Add/Alter - Add/Alter
$234,243Issued
2026-10-20 • 416 FAIRFAX AVE SAN MATEO 94402-2210 CA
Single Family (Alteration/Repair) - Alter - Alter
$7,500Issued
2026-10-19 • 1464 WOODBERRY AVE SAN MATEO 94403-3765 CA
Single Family (Alteration/Repair) - Kitchen & Bath Remodel (Flat) - Kitchen & Bath Remodel (Flat)
$30,000Issued
2026-10-19 • 723 COSTA RICA AVE SAN MATEO 94402-1014 CA
Single Family (New) - New - New
$197,500Issued
2026-10-18 • 2630 ALAMEDA DE LAS PULGAS SAN MATEO 94403-2652 CA
Single Family (Addition) - Add/Alter - Add/Alter
$285,704Issued
2026-10-17 • 3513 CASANOVA DR SAN MATEO 94403-2908 CA
Single Family (Alteration/Repair) - Alter - Alter
$15,815Under Review

Parcel & Zoning Info

APN041111440
Official Lot Sqft9,483
Zoning CodeR-1, S-8
SB 9 StatusEligible · up to 4 units
SB 9 Block Reasons No SB 9 disqualifiers found
Development Blockers
Landslide
Unlock Pathways
Ministerial ADU Ministerial SB 9 Density Bonus
Entitlement RiskLow (0/100)

ADU Potential

Feasibility Score70/100
Max ADU Units2 (ADU + JADU)
Est. ADU Size1,200 sqft
Existing Coverage41.2%

Flag / irregular · ~123 ft frontage × 132 ft deep, a tucked-away rear unit is very private; access is typically via the pole driveway.

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.

Seller Motivation

Motivation Score30/100
Some motivation
90+ days on market

Inferred from days on market and listing-description language (e.g. "as-is", "estate sale", "motivated seller"). A screening heuristic for likely negotiability, not a statement about the seller's circumstances.

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

Highlands Elementary

San Mateo-Foster City

0.6 miles away
Middle School

Borel Middle

San Mateo-Foster City

1.7 miles away
High School

Hillcrest at Youth Services Center

San Mateo County Office of Education

1.2 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

68/100

Based on recent sales velocity and local demand in 94402.

Flippability Score

15/100

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

Bidding War Prob.

51%

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.

Median of 12 recent single-family sales in San Mateo (94402): $1,516/sqft, plus 5% because new houses sold at a median 1.07x their comps across 239 real rebuilds. Sized within 50% of the 5,900 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$3,245,000
New Build5,900 sqft
Total Capital Required$9,015,000
Estimated Resale (ARV)$9,392,800
Cost of Sale (5%)-$469,640
Carry (33mo @ 7%)-$1,406,213
Net Proceeds$7,516,948

Projected Profit

-$1,498,053
-16.6% ROI

Warning: Project is mathematically underwater.

Recent Comparables (San Mateo 94402)

Sized to the modelled 5,900 sqft build: sales within 50% of it. Smaller houses sell for more per foot, so pricing a rebuild off them overstates resale.

769 Crescent Ave

Sold
$4,705,000
Sold: 2026-10-09
Lot: 6,122
Sqft: 2970
$/Sqft: $1,584

2012 Timberlane Way

Sold
$2,700,000
Sold: 2026-09-16
Lot: 10,130
Sqft: 3820
$/Sqft: $707

404 Hillsborough Blvd

Sold
$4,075,000
Sold: 2026-09-10
Lot: 12,306
Sqft: 2950
$/Sqft: $1,381

554 Edgewood Rd

Sold
$5,000,000
Sold: 2026-08-12
Lot: 14,207
Sqft: 3205
$/Sqft: $1,560

613 Barroilhet Ave

Sold
$5,475,000
Sold: 2026-07-31
Lot: 11,200
Sqft: 3342
$/Sqft: $1,638

111 Aragon Blvd

Sold
$4,050,000
Sold: 2026-07-27
Lot: 6,600
Sqft: 3020
$/Sqft: $1,341

537 Hurlingham Ave

Sold
$6,600,000
Sold: 2026-07-14
Lot: 15,923
Sqft: 3640
$/Sqft: $1,813

521 Dorchester Rd

Sold
$4,660,000
Sold: 2026-07-14
Lot: 9,422
Sqft: 4120
$/Sqft: $1,131

721 Edgewood Rd

Sold
$11,775,000
Sold: 2026-07-01
Lot: 31,980
Sqft: 5500
$/Sqft: $2,141

420 W Poplar Ave

Sold
$5,400,000
Sold: 2026-06-29
Lot: 11,006
Sqft: 3195
$/Sqft: $1,690

429 Virginia Ave

Sold
$4,800,000
Sold: 2026-06-12
Lot: 8,605
Sqft: 3270
$/Sqft: $1,468

641 Crescent Ave

Sold
$5,420,000
Sold: 2026-06-09
Lot: 14,585
Sqft: 3680
$/Sqft: $1,473