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Single Family ResidenceResidential
$378,417$416 / ft²
TopHap EstimateOur estimate of what this home would sell for today, based on nearby sales, the home's size and features, and local price trends. It is a starting point, not an appraisal.· confidence 97How well the pricing models agreed with each other on this home. Higher means the estimate rests on stronger, more consistent data.· as of Sep 24, 2026
Last sold for $289,000 on Aug 15, 2019

18 UNDERROCK RD

SPARTA, NJ 07871
0
Baths
910 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.
0.46 ac
Lot SizeThe size of the land the home sits on, from county records.
1953
Year BuiltThe year the home was originally built, according to county records.
1
StoriesHow many floors the home has above ground.

Valuation

$378K
$365K low$391K high
Last SaleThe most recent sale price and date from the recorded deed. Transfers between family members or companies may not reflect market value.$289,000 · Aug 15, 2019

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$7,611 (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.$207,500 (2026)
Assessed LandThe share of the county's assessed value that comes from the land itself, not the buildings.$123,400
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$84,100
Previous AssessedThe county's assessed value from the year before, useful for seeing how the assessment changed.$207,500
Assessor Market ValueThe county assessor's own opinion of market value. It is separate from our estimate and updates on the county's schedule.$207,500

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.43
1
FloodProjected flooding risk from rivers, heavy rain, and storm surge, scored 0 to 100. Higher is riskier.
20
WildfireProjected wildfire risk, scored 0 to 100, based on how much land burns in a typical year. Higher is riskier.
57
HeatProjected heat risk, scored 0 to 100, based on how many extremely hot days a year are expected. Higher is riskier.
97
StormProjected risk from heavy rainstorms, scored 0 to 100, based on how often extreme rainfall is expected. Higher is riskier.
40
DroughtProjected water shortage risk, scored 0 to 100. Higher means more strain on the local water supply.
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.minimal

Scores 0–100; higher = greater projected risk.

Property Facts

Property TypeThe broad category the county puts this property in, such as residential or commercial.Single Family Residence
StyleThe architectural style of the home, such as ranch or colonial.Ranch
CountySUSSEX
Lot (acres)The size of the land the home sits on, from county records.0.46
PoolWhether the property has a pool, and what kind, such as in-ground.No

Transaction History(3)

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.

H
Sparta High SchoolB-
High · Grades 9–12 · 1.6 mi
M
Sparta Middle SchoolB
Middle · Grades 6–8 · 1.6 mi
E
Sparta Alpine School
Elementary · Grades PK–2 · 3.5 mi

District: Sparta Township School District

Neighborhood · ZIP 07871These 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.17
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.94
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.96

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.93%
Bachelor's or higherThe share of adults 25 and older whose highest degree is a bachelor's degree.38%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.5.0%
UnemploymentThe share of men 16 and older who are out of work and actively looking. Only men are counted in this figure.1.4%
PopulationHow many people live in this area.21,461
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.530 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$163,529
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$191,626
Average tempThe average temperature here across a full year.48°F
Annual precipHow much rain and melted snow falls here in a typical year.50 in
SunshineThe share of daylight hours that get direct sun in a typical year, counting cloud cover.56%

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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

18 Underrock Rd 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.

  • Worth less than 90% of homes in Sparta 07871
  • Costs more per square foot than 90% of homes in Sussex County
  • Smaller than 95% of homes in Sparta 07871
  • Older than 76% of homes in Sussex County

What homes are worth in Sparta 07871

Each bar is how many homes fall in that price range. The marker is this home.

This home
$129K$1.7M

This home is worth more than 10% of homes in Sparta 07871.

How it measures up in Sparta 07871

The dot is this home. The mark in the middle is the typical home in Sparta 07871.

Estimated value$378,417
CheaperTypical $628,136Pricier

Pricier than 10% of homes nearby

Price per ft²$416
CheaperTypical $309Pricier

Pricier than 83% of homes nearby

Living area910 ft²
SmallerTypical 2,090 ft²Bigger

Bigger than 5% of homes nearby

Lot size0.46 ac
SmallerTypical 0.48 acBigger

Bigger than 48% of homes nearby

Year built1953
OlderTypical 1973Newer

Newer than 27% of homes nearby

How 18 Underrock Rd ranks against every home in each area.
MeasureThis homeSparta 07871Sussex County
Estimated valuepricier than$378,41710% of homes34% of homes
Price per ft²pricier than$41683% of homes90% of homes
Living areabigger than910 ft²5% of homes12% of homes
Lot sizebigger than0.46 ac48% of homes56% of homes
Year builtnewer than195327% of homes24% of homes

About 18 Underrock Rd

How much is 18 Underrock Rd, Sparta, NJ worth?

The TopHap Estimate for 18 Underrock Rd, Sparta, NJ is $378,417 as of Sep 24, 2026. The likely range is $365,387 to $391,447. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 18 Underrock Rd, Sparta, NJ last sell?

18 Underrock Rd, Sparta, NJ last sold on Aug 15, 2019 for $289,000, according to the county's recorded deed. TopHap holds 3 recorded sales for this parcel.

How big is 18 Underrock Rd, Sparta, NJ?

18 Underrock Rd, Sparta, NJ has 910 square feet of living space and a 0.46-acre lot.

When was 18 Underrock Rd, Sparta, NJ built?

18 Underrock Rd, Sparta, NJ was built in 1953, making it 73 years old. It is a ranch home. The building has 1 story.

What schools serve 18 Underrock Rd, Sparta, NJ?

18 Underrock Rd, Sparta, NJ is assigned to Sparta High School (high), rated B-; Sparta Middle School (middle), rated B; Sparta Alpine School (elementary). All sit in Sparta Township School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 18 Underrock Rd, Sparta, NJ compare to other homes in Sparta 07871?

Among the 8,328 homes in Sparta 07871, it is worth more than 10% of them ($378,417 against a typical $628,136), its price per square foot is higher than 83% of them ($416 against a typical $309), it is bigger than 5% of them (910 ft² against a typical 2,090 ft²), its lot is bigger than 48% of them (0.46 ac against a typical 0.48 ac) and it is newer than 27% of them (1953 against a typical 1973). Measured against all of Sussex County, it is worth more than 34% of homes there. These shares are recounted nightly from the full county assessor record for each area, not from active listings.

What are the property taxes on 18 Underrock Rd, Sparta, NJ?

The 2025 property tax bill for 18 Underrock Rd, Sparta, NJ was $7,611. The county assessed it at $207,500.

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