768 of Copiague’s 7,472 homes, 10.3%, are in two-unit buildings, and another 237 are in buildings of three or four units. That is a lot of shared roofs for a hamlet of houses, and it changes how a job is planned: two households, one attic, one basement and often one owner paying for heat that the other unit loses. The rest of the stock is more familiar. 76.6% of homes are detached houses, 3.4% are townhouses and other attached homes, and 78.6% of occupied homes are owner-occupied.
Copiague is a hamlet in the Town of Babylon, 3.2 square miles between Amityville to the west, North Amityville to the north and Lindenhurst to the east, running south to the Great South Bay. The median home dates from 1963. The 1950s alone account for 26.6% of the stock, 1,984 homes, and the 1940s and 50s together for 35.4%, slightly ahead of the 34.7% built in the 1960s and 70s. Only 6.8% has gone up since 2000.
Utility gas heats 68.6% of occupied homes, fuel oil 22.5%, electricity 5.5% and bottled gas 2.5%. PSEG Long Island supplies the electricity, and National Grid gas lines serve many Copiague streets, though not every one. In a gas house the savings from sealing and insulating show up on the National Grid bill; in the oil houses, as fewer deliveries.
The houses we insulate in Copiague
The 1,984 homes of the 1950s and the 663 of the 1940s are mostly capes and small ranches. A Copiague cape that has had its upstairs finished loses heat at the knee walls, the short walls between the bedrooms and the triangle of attic behind them, where the floor joists run open under the wall into the heated rooms below. The sloped ceilings above the bedrooms hold a thin batt against the roof deck, and the small flat attic at the top often has a few inches of loose-fill and an unsealed hatch. A shed dormer added later brings its own low roof and a cheek wall that was rarely insulated well.
The 1,340 homes of the 1960s and 1,256 of the 1970s are ranches, high ranches and splits. Their loss is spread across a long attic floor with batts laid between the joists, gaps at the top plates and around the chimney, recessed lights and bath fans open to the attic, and, in the high ranch, a lower level whose rim joist and garage ceiling are left bare. The 635 homes built before 1940 we check for balloon framing and knob-and-tube wiring before any cavity is filled.
South of Montauk Highway (Merrick Road), Copiague divides into three peninsulas on the bay: Amity Harbor to the southwest, Copiague Harbor in the middle and American Venice to the southeast. Houses close to the water are more likely to sit over crawl spaces or slabs than full basements, and the ground under them is often damp. We treat a crawl space there as wet until a moisture reading says otherwise, and we do not put anything in it that holds water. Wind off the bay also finds every unsealed eave.
The 301 homes built from 2010 to 2019 went up under recent codes with insulated walls; if they need anything, it is usually attic ductwork or a room over a garage. The 101 homes in buildings of fifty or more units and the 93 in buildings of twenty to forty-nine are a board or management decision, not a single owner’s.
Two-family houses in Copiague: one roof over two households
Whether a Copiague two-family was framed that way or began as a single house that gained a second apartment, the envelope questions are the same. The attic sits over the upper unit only. The floor between the units is not an outside surface, except at its edges, where the rim joist at the second floor is open to the wall cavity and to outside air. The stair, if it is shared, often runs straight up to an attic hatch at the top, and the basement holds either one heating plant for both apartments or two.
That is why we scope a two-family as one building. Sealing and insulating the attic helps the top unit most. Sealing the basement rim and the stair helps the bottom unit most. The rim at the second floor, the plumbing chase that runs through both apartments and the chimney chase that passes both are shared, and leaving any of them for later means the other unit keeps drafting through it.
We need access to the attic hatch, which is often in the upstairs tenant’s closet, and to the basement, which may be the downstairs tenant’s storage. An owner who lives in one unit and rents the other should schedule both apartments for the same visit. Where one owner pays for heat for both units, sealing the tenant’s half pays off just as directly as sealing their own.
We seal before we insulate
Insulation reduces heat conducted through a surface; air leaking through a gap carries heat straight past it. In a Copiague cape the worst gap is the one nobody can see, where the floor joists run from the heated first floor into the cold space behind the knee wall.
So the sequence starts there: block and seal those joist bays, put a rigid air barrier on the attic side of the knee wall, seal the tops of the dormer cheek walls, and set baffles in the slopes so the roof can still vent. Then the flat attic: seal around the chimney with metal and fire-rated sealant, seal the plumbing stack and the hatch. Then insulate, knee walls and slopes first and the flat to full depth last. In a two-family add the rim at each floor level and the top of the stair.
If a quote specifies a depth of insulation and never mentions air sealing, it is half a job.
What insulation costs in Copiague
Most of our projects run between $3,500 and $12,500. A 1960s ranch with one open attic is usually at the lower end. A 1950s cape with a finished upstairs costs more for its size, because the knee walls, the slopes and the flat attic are three separate pieces of work. A two-family is priced as one building, with the attic over the top unit, the rim at every level and the basement all in the number. A crawl space near the bay adds sealing and moisture control. Our spray foam cost guide has more on the foam side.
Open cell foam runs R-3.9 to R-4.2 per inch. Closed cell runs R-6.9 to R-7.1 per inch and also acts as a vapor retarder, which is why it costs more and why it is right in some assemblies and unnecessary in others. All products are manufactured in the United States and meet applicable building code and safety standards. ENERGY STAR says sealing air leaks and adding insulation can save up to 10% on annual energy bills.
Insulation rebates in Copiague
Copiague is served by PSEG Long Island for electricity and by National Grid for gas on the streets its lines reach. Because PSEG Long Island is the electric company, NYSERDA’s Comfort Home program is not an option for Copiague homes.
The utility program is PSEG Long Island’s. After a free Whole House Energy Assessment, which covers insulation and drafts with a thermal scan and a blower door test, PSEG Long Island lists a $2,500 insulation rebate and a $1,000 air-sealing rebate for market-rate single-family homes, and higher amounts for income-qualified homes and homes in state-designated disadvantaged communities. Gas, oil, propane and electric heat all qualify, air sealing has to accompany the insulation, and the money flows only through PSEG Long Island’s participating contractors. Its 2026 list describes single-family homes, so a two-family owner should ask PSEG Long Island how the building is treated before counting on it.
EmPower+ is written for one- to four-family homes, two-families included, and for owners and renters alike. For a Suffolk household under the limit, NYSERDA’s EmPower+ program can pay for air sealing and insulation at no cost up to $14,000 at the lower-income tier (at or below $98,925 for four people), or half the cost up to $7,000 at the moderate-income tier (below $131,900 for four), plus up to $1,600 in federal HEAR funds for air sealing, insulation and ventilation, all through an EmPower+ contractor. Long Island households should check eligibility on the MyEnergy portal. National Grid’s own Long Island insulation rebate program is not taking new applications.
Tenants and owners at or below PSEG Long Island’s 2026 income guideline ($131,900 for four) can also ask for a free REAP energy survey, which may leave door sweeps, an attic hatch cover, LED bulbs and a smart thermostat, with a $50 bill credit and a $35 voucher; REAP does not install insulation. Each program uses its own contractors; check its list before you sign. There is no federal insulation tax credit on a 2026 job: Section 25C ended for work placed in service after 31 December 2025. New York has no state tax credit for insulation either. Our New York and New Jersey rebate guide sets out every program.
Code and climate in Copiague
78.7% of Copiague’s homes were built before 1980. The capes and ranches of the 1940s, 50s and 60s all predate New York’s first statewide energy code, which took effect on 1 January 1979. Suffolk County is Climate Zone 4.
Today’s standard for new homes is the 2025 Energy Conservation Construction Code of New York State, in force since 31 December 2025. It calls for R-49 in ceilings, with R-38 accepted over the whole ceiling if that R-38 runs at full, uncompressed height over the wall top plate at the eaves. It sets floors at R-30; basement and crawl space walls at R-15 continuous, R-19, or R-13 plus R-5 continuous; windows at U-0.27; and air leakage at no more than 3.0 air changes per hour at 50 pascals.
Existing homes are handled separately. The parts of a house that are not being altered do not have to comply, and New York’s code does not require a blower door test when you insulate an existing home. But where an alteration opens wall or roof cavities, they must be insulated to full depth, which is the moment to do it when an apartment is gutted between tenants. ENERGY STAR puts the attic target for this zone at R-60 for an attic with no insulation and R-49 for one that already has 3 to 4 inches.
Common questions about insulation in Copiague
Do you install insulation in Copiague, NY?
Yes, across the hamlet, down to Amity Harbor, Copiague Harbor and American Venice. Most of our Copiague work is the 1950s cape and the 1960s and 70s ranch and high ranch, and a good share is two-family houses, which make up 10.3% of the hamlet’s homes. We also work on the pre-war houses and on townhouses where the owner controls the attic. Larger apartment buildings are a decision for their boards or owners. Call and we will tell you where your building fits.
How much does insulation cost in Copiague?
Most projects run $3,500 to $12,500. A 1960s ranch with a single open attic sits near the low end. A 1950s cape with a finished upstairs costs more for its size, because the knee walls, slopes and flat attic are separate work. A two-family is priced as one building, including the attic over the top unit, the rim at each floor and the basement. A damp crawl space near the bay adds sealing and moisture work. The written price comes after a free walk-through.
Are there insulation rebates in Copiague?
Copiague is PSEG Long Island territory. PSEG Long Island lists a $2,500 insulation rebate and a $1,000 air-sealing rebate for market-rate single-family homes, more for income-qualified homes, paid through its participating contractors after a free Whole House Energy Assessment; two-family owners should confirm eligibility with PSEG Long Island. Comfort Home is not available to PSEG Long Island homes. EmPower+ covers income-eligible owners and renters in one- to four-family homes. The federal 25C credit has ended, and New York has no state insulation credit.
We live upstairs in our Copiague two-family and rent out the downstairs. Can we insulate only our unit?
You can, and the attic over your apartment is the biggest single piece of the job. But part of what makes your floor cold is shared: the rim joist at your floor level, the stair and the plumbing and chimney chases run through both units. Doing those at the same visit costs less than coming back, and the tenant’s unit gets tighter at the same time. We need access to the basement either way, so plan the day with your tenant. EmPower+ accepts renters if they qualify.
Free energy audit in Copiague
In a Copiague cape we start upstairs: behind the knee walls, in the slopes and the flat attic, and at the dormers. In a ranch we walk the attic floor and the eaves. In a two-family we go through both units, the stair, the attic over the top floor and the basement, and we look at how the heat is split and metered. Near the bay we check the crawl space for moisture before we plan anything for it. Then a written scope and price, free and without obligation.
Call 914-825-6824 or use our contact form. We are open 8am–8pm, seven days, and work out of New Rochelle, NY with a 100-plus in-house crew that never subcontracts.
Learn more
- Insulation contractors across Suffolk County
- Insulation in Lindenhurst
- Insulation in North Amityville
- Insulation in West Babylon
- Attic insulation
- Crawl space insulation
- Air sealing