How old are the homes in Green Knoll, NJ?

Name: Age of homes in Green Knoll, NJ, 2020–2024
Creator: US Census Bureau
License: https://www.census.gov/data/developers/about/terms-of-service.html

51.1% (±8.2 points) of the homes in Green Knoll, NJ were built before 1980 (2020–2024 American Community Survey).

4.3% were built before 1940.

3.9% were built in 2010 or later.

Figures last updated on November 12, 2026.

Built before 1980: 51.1% (±8.2 points)
Built before 1940: 4.3%
Built 2010 or later: 3.9%

When the homes in Green Knoll were built

Housing units by year structure built, 2020–2024
Year built	Green Knoll	Somerset County	New Jersey	United States
2020 or later	0.0% (±1.8 points)	1.3%	1.1%	2.0%
2010 to 2019	3.9% (±2.7 points)	6.1%	6.2%	9.4%
2000 to 2009	7.1% (±2.9 points)	9.7%	9.2%	13.6%
1990 to 1999	14.8% (±4.4 points)	16.8%	8.9%	12.4%
1980 to 1989	23.2% (±5.9 points)	19.7%	11.8%	12.9%
1970 to 1979	8.6% (±3.4 points)	9.3%	12.3%	14.2%
1960 to 1969	18.4% (±5.2 points)	12.9%	12.8%	9.9%
1950 to 1959	16.5% (±3.7 points)	10.3%	13.8%	9.5%
1940 to 1949	3.3% (±3.1 points)	4.5%	6.5%	4.4%
1939 or earlier	4.3% (±2.2 points)	9.3%	17.4%	11.7%

In Green Knoll, the share of homes built before 1980 is not measurably different from Somerset County (46.3%).

It is also lower than in New Jersey (62.8%).

It is not measurably different from the national figure (49.7%).

In Somerset County, Green Knoll ranks 9 of 24 places with a published estimate, from highest to lowest share of homes built before 1980.

Statewide, it ranks 159 of 252.

Rankings use the estimates alone; where margins of error overlap, neighboring ranks may not truly differ.

Why the age of a home matters: lead-based paint

Federal law treats housing built before 1978 as likely to contain lead-based paint.

Before a lease or sale of most pre-1978 housing, the landlord or seller must disclose any known lead-based paint and hazards and give the tenant or buyer the EPA pamphlet (42 U.S.C. § 4852d; 40 CFR part 745, subpart F; 24 CFR part 35, subpart A).

A contractor paid to renovate, repair or paint a pre-1978 home must be a certified firm, use a certified renovator and follow lead-safe work practices under the Renovation, Repair and Painting Rule (40 CFR part 745, subpart E) whenever the job disturbs more than 6 square feet of painted surface in a room or more than 20 square feet outside; window replacement and demolition always count (40 CFR 745.83).

Certification comes from EPA, or from the state where EPA has authorized the state to run the program.

The Census Bureau groups construction by decade, so the share built before 1978 lies between the share built before 1970 (42.5%) and the share built before 1980 (51.1%).

Homes built before 1980 in places near Green Knoll

Nearest places with a published estimate, compared with Green Knoll
Place	Distance	Homes built before 1980	Compared with this place
Green Knoll	—	51.1% (±8.2 points)	—
Bridgewater Center	1.7 mi	72.4% (±9.9 points)	Higher
Martinsville	2.0 mi	61.9% (±6.9 points)	Higher
Somerville Borough	2.4 mi	76.1% (±7.7 points)	Higher
Raritan Borough	2.8 mi	58.3% (±8.8 points)	Not measurably different
The Hills	3.4 mi	3.4% (±2.1 points)	Lower
Bradley Gardens	3.4 mi	23.9% (±4.8 points)	Lower
Finderne	3.7 mi	56.6% (±13.1 points)	Not measurably different
Liberty Corner	4.3 mi	48.0% (±16.7 points)	Not measurably different

Nearby places with a measurably lower figure: The Hills, NJ (3.4%), Bradley Gardens, NJ (23.9%).

Nearby places with a measurably higher figure: Bridgewater Center, NJ (72.4%), Martinsville, NJ (61.9%), Somerville Borough, NJ (76.1%).

Distance is measured in a straight line between the Census Bureau’s internal points for each place.

Homes built before 1980 across Somerset County, place by place

Rank	Place	Homes built before 1980
3	Kingston	68.7% (±30.6 points)
4	East Franklin	62.1% (±13.0 points)
5	Basking Ridge	62.0% (±9.7 points)
6	Martinsville	61.9% (±6.9 points)
7	Middlebush	57.1% (±25.8 points)
8	Finderne	56.6% (±13.1 points)
9	Green Knoll	51.1% (±8.2 points)
10	Somerset	49.4% (±6.2 points)
11	Liberty Corner	48.0% (±16.7 points)
12	Lyons	32.8% (±9.2 points)
13	Blackwells Mills	31.2% (±6.0 points)
14	Hillsborough	30.9% (±4.2 points)
15	Ten Mile Run	30.3% (±21.5 points)

Showing 13 of 24 places in Somerset County, ranked from highest to lowest.

Green Knoll is a census-designated place: an unincorporated community the Census Bureau draws for statistics, with no municipal government of its own.

It lies inside Bridgewater Township, whose figures include it.

Survey years: 2020–2024 (American Community Survey 5-year estimates).

Margins of error are at the 90% confidence level.

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Questions about Green Knoll

How old are most homes in Green Knoll?

51.1% of homes in Green Knoll, NJ were built before 1980 (2020–2024 American Community Survey).

Do homes in Green Knoll need a lead paint disclosure?

A home built before 1978 does, before it is rented or sold, unless an exemption applies (42 U.S.C. § 4852d); between 42.5% and 51.1% of homes in Green Knoll were built before then.

Does a contractor need lead certification to work on older homes in Green Knoll?

Yes, when the job disturbs more than 6 square feet of paint in a room or 20 square feet outside, or replaces a window: the firm must be certified and a certified renovator must direct the work under the Renovation, Repair and Painting Rule (40 CFR part 745, subpart E).

Sources

Selected Housing Characteristics (DP04), 2020–2024 ACS 5-year estimates — Green Knoll CDP, New Jersey

To check these figures in the Census Bureau’s own API, request the variables below from the 2024 ACS 5-year data profile (acs/acs5/profile) for Green Knoll CDP, New Jersey (place:27840, in state:34).

Each estimate (E or PE) has a margin of error beside it (M or PM).

The API needs a free key.

Request a Census API key.

DP04_0017PE, DP04_0017PM, DP04_0018PE, DP04_0018PM, DP04_0019PE, DP04_0019PM, DP04_0020PE, DP04_0020PM, DP04_0021PE, DP04_0021PM, DP04_0022PE, DP04_0022PM, DP04_0023PE, DP04_0023PM, DP04_0024PE, DP04_0024PM, DP04_0025PE, DP04_0025PM, DP04_0026PE, DP04_0026PM

This product uses the Census Bureau Data API but is not endorsed or certified by the Census Bureau.

Figures are published by the US Census Bureau, HUD, the Bureau of Labor Statistics and the FBI; Seayora reproduces them and does not adjust them, except where a sentence says it compares dollar figures after inflation. They describe the whole place, not any one building or street, and are not an appraisal, a rent determination, a tax bill, a safety rating or legal advice.