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Duplex (2 Units, Any Combination)Residential

20 ROBERTSON LN

COS COB, CT 06807
4
Beds
2.5
Baths
2,418 ft²
Living AreaTotal finished area of the structures, from county records. Some counties include shared space like hallways or a building gym, so it may not match a listing.
0.24 ac
Lot SizeThe size of the land the home sits on, from county records.
1962
Year BuiltThe year the home was originally built, according to county records.
2
StoriesHow many floors the home has above ground.
11
RoomsThe total room count in county records. Counties differ on which rooms they count, so compare it loosely.

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$8,454 (2025)
Assessed ValueThe value the county assigns to this home to calculate property tax. It is often lower than what the home would sell for.$684,040 (2025)
Assessed LandThe share of the county's assessed value that comes from the land itself, not the buildings.$480,550
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$203,490
Previous AssessedThe county's assessed value from the year before, useful for seeing how the assessment changed.$684,040
Assessor Market ValueThe county assessor's own opinion of market value. It is separate from our estimate and updates on the county's schedule.$478,828

Climate Risk

Overall riskThe average of the five hazard scores below, on a 0 to 100 scale. Higher means greater projected risk over the coming decades.51
48
FloodProjected flooding risk from rivers, heavy rain, and storm surge, scored 0 to 100. Higher is riskier.
5
WildfireProjected wildfire risk, scored 0 to 100, based on how much land burns in a typical year. Higher is riskier.
64
HeatProjected heat risk, scored 0 to 100, based on how many extremely hot days a year are expected. Higher is riskier.
96
StormProjected risk from heavy rainstorms, scored 0 to 100, based on how often extreme rainfall is expected. Higher is riskier.
43
DroughtProjected water shortage risk, scored 0 to 100. Higher means more strain on the local water supply.
Projected Flood DepthHow deep a serious flood is expected to get here at some point in the next 30 years. Shown in inches.24 in
30-Year Flood ChanceThe chance of at least one serious flood here in the next 30 years, not in any single year.48%
FEMA Flood ZoneFEMA's flood zone for this address. Zones starting with A or V are high risk, and lenders usually require flood insurance there.1 percent flood zone

Scores 0–100; higher = greater projected risk.

Property Facts

Property TypeThe broad category the county puts this property in, such as residential or commercial.Duplex (2 Units, Any Combination)
StyleThe architectural style of the home, such as ranch or colonial.Duplex Single
CountyWESTERN CONNECTICUT
Effective Year BuiltAn adjusted build year that accounts for condition and major remodels. A big renovation can make a home count as newer than it is.1965
Lot (acres)The size of the land the home sits on, from county records.0.24
ConstructionThe main material the home's frame and walls are built from.Frame (Unspecified)
RoofThe main material covering the roof, such as asphalt shingle or tile.Asphalt
HeatingThe type of heating system in the home.Hot Water
FireplaceWhether the home has a fireplace, and what kind.Yes
PoolWhether the property has a pool, and what kind, such as in-ground.No

Transaction History(1)

Sales and refinances filed with the county for this home. Not every transfer is a normal sale, so check the type before comparing prices.

Assigned SchoolsThe public schools this address is zoned for. Boundaries change, so confirm with the district before you count on it.

E
Cos Cob SchoolB
Elementary · Grades KG–5 · 0.2 mi
M
Central Middle SchoolA-
Middle · Grades 6–8 · 0.9 mi
H
Greenwich High SchoolA+
High · Grades 9–12 · 0.9 mi

District: Greenwich School District

Neighborhood · ZIP 06807These are comparison scores, not percentages. 100 equals the national average, so 150 means about 50% above average.

CrimeLocal crime compared with the rest of the country, where 100 is average. It reflects things like population density, income, and how crime gets reported.54
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.112
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.103

Index scale: 100 = US average (tick). Lower is better.

Homes occupiedThe share of homes here that someone lives in. The rest sit empty, including vacation and for-sale homes.94%
Bachelor's or higherThe share of adults 25 and older whose highest degree is a bachelor's degree.34%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.6.3%
UnemploymentThe share of men 16 and older who are out of work and actively looking. Only men are counted in this figure.1.0%
PopulationHow many people live in this area.7,630
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.2,321 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$180,144
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$235,340
Average tempThe average temperature here across a full year.52°F
Annual precipHow much rain and melted snow falls here in a typical year.51 in
SunshineThe share of daylight hours that get direct sun in a typical year, counting cloud cover.58%

Data by ATTOM. Valuations are automated estimates, not appraisals. Photos from Google Street View and may not depict the current property state.

How this home compares

20 Robertson Ln measured against every home in its neighborhood, its ZIP code and its county, using county assessor records refreshed nightly. A home can stand out in one of those areas and look ordinary in another, because each one holds a different mix of homes.

  • Has a smaller lot than 77% of homes in Western Connecticut County

How it measures up in Cos Cob 06807

The dot is this home. The mark in the middle is the typical home in Cos Cob 06807.

Living area2,418 ft²
SmallerTypical 2,388 ft²Bigger

Bigger than 51% of homes nearby

Lot size0.24 ac
SmallerTypical 0.29 acBigger

Bigger than 36% of homes nearby

Year built1962
OlderTypical 1964Newer

Newer than 49% of homes nearby

How 20 Robertson Ln ranks against every home in each area.
MeasureThis homeCos Cob 06807Western Connecticut County
Living areabigger than2,418 ft²51% of homes63% of homes
Lot sizebigger than0.24 ac36% of homes23% of homes
Year builtnewer than196249% of homes43% of homes

About 20 Robertson Ln

When did 20 Robertson Ln, Cos Cob, CT last sell?

20 Robertson Ln, Cos Cob, CT last sold on Jan 1, 1900, according to the county's recorded deed.

How big is 20 Robertson Ln, Cos Cob, CT?

20 Robertson Ln, Cos Cob, CT has 4 bedrooms, 2.5 bathrooms, 2,418 square feet of living space and a 0.24-acre lot.

When was 20 Robertson Ln, Cos Cob, CT built?

20 Robertson Ln, Cos Cob, CT was built in 1962, making it 64 years old. It is a duplex single home. The building has 2 stories.

What schools serve 20 Robertson Ln, Cos Cob, CT?

20 Robertson Ln, Cos Cob, CT is assigned to Cos Cob School (elementary), rated B; Central Middle School (middle), rated A-; Greenwich High School (high), rated A+. All sit in Greenwich School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 20 Robertson Ln, Cos Cob, CT compare to other homes in Cos Cob 06807?

Among the 2,396 homes in Cos Cob 06807, it is bigger than 51% of them (2,418 ft² against a typical 2,388 ft²), its lot is bigger than 36% of them (0.24 ac against a typical 0.29 ac) and it is newer than 49% of them (1962 against a typical 1964). These shares are recounted nightly from the full county assessor record for each area, not from active listings.

What are the property taxes on 20 Robertson Ln, Cos Cob, CT?

The 2025 property tax bill for 20 Robertson Ln, Cos Cob, CT was $8,454. The county assessed it at $684,040.

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