East Islip runs on oil. 53.3% of the hamlet’s occupied homes heat with fuel oil, against 26.9% on utility gas and 12.3% on electricity, and the houses burning it are old: 86.7% of East Islip’s 4,811 homes were built before 1980, and the median home dates from 1958. The largest single decade is the 1950s, with 1,744 homes, 36.3% of the stock.
East Islip is a hamlet in the Town of Islip, on the Great South Bay, between Islip to the west and Great River to the east. 86.0% of its homes are detached houses and 90.0% of occupied homes are lived in by their owners. The main exception is the 317 homes, 6.6% of the stock, in buildings of fifty or more units.
So the typical job is a 1940s or 50s house, 41.7% of the hamlet, with 814 more from before 1940. In an oil-heated house every hour the burner runs to replace heat lost through an open attic floor or a bare rim joist is paid for by the gallon, so the savings arrive as fewer deliveries, and sealing usually pays back faster than in the same house on gas.
The houses we insulate in East Islip
This was estate country before it was a suburb. William Nicoll bought the land from the Secatogue in 1683, 51,000 acres reaching from Babylon to Bayport, and built Islip Grange near the shore of what is now Heckscher State Park. The Hollins, Gulden and Knapp estates followed, and Brookwood Hall, the Thorne family’s mansion, is now a Town of Islip municipal building. Much of today’s East Islip went up on estate land that was sold off, most notably the Percy G. Williams estate, in neighborhoods such as Deer Run, Country Village and Beecher Estates, with The Moorings, a guard-gated waterfront community, on the bay.
The 1,744 homes of the 1950s and 263 of the 1940s are the core of the work. Most went up with little insulation and have been topped up piecemeal since: a few inches of batts on the attic floor from a later decade, a cape’s knee walls lined on the room side and open behind, exterior walls never filled. The attic floor leaks at the top plates, the plumbing stack, the chimney and every fixture cut into the ceiling, and the basement rim joist is usually bare. In a cape the joist bays under the knee walls run open to the eave, so the upstairs bedroom floor sits in outdoor air all winter.
The 844 homes of the 1960s and 504 of the 1970s are ranches, splits and high ranches, most with 3 to 4 inches of batts on the attic floor, thinned at the eaves. A high ranch adds a garage ceiling under a bedroom. The 201 homes of the 1980s and 277 of the 1990s went up after New York’s first energy code, with fuller walls, but their attics still leak at the hatch, the recessed lights and the ducts.
The 814 homes from before 1940, 16.9% of the hamlet, are each a separate case. A house that old has usually been changed many times: a porch closed in, a kitchen pushed out, a heating system replaced. We expect wall cavities with no fire blocking, wiring that has to be checked before insulation goes near it, and plaster that stays in place while cellulose is dense-packed through small holes. The first visit is mostly mapping.
Boilers and baseboard pipes: insulating a hot water house
An oil-heated Long Island house of this age very often heats with water: a boiler in the basement pumping hot water through copper pipe to baseboard or radiators. With 53.3% of East Islip on oil, that shapes how a house gets insulated, because the heating pipes travel through exactly the places insulation goes.
The loops run along the basement ceiling, behind baseboards on exterior walls, and in capes and additions sometimes through a knee-wall attic or over a crawl space. Put insulation on the wrong side of a pipe and the pipe ends up in the cold: fill a knee-wall space with a supply loop left outside the insulation, and a January cold snap can freeze it. So we trace the loops first, and a pipe in a space we are closing off goes on the warm side of the new insulation or gets insulated itself. In most boiler houses we would rather seal and insulate the basement walls and rim joist than the basement ceiling, so the boiler and every pipe in the room stay inside the heated house.
There are no supply ducts in a boiler house’s attic, so the attic is simpler, but the chimney chase beside the flue is often the largest single opening into it, and it gets closed with sheet metal and fire-rated sealant, never foam against the masonry. Baseboard covers hide the holes where each pipe rises through the floor; they are small and many, and we seal them from the basement. A tighter house still has to feed the burner, so we check the boiler’s combustion air before closing up its room.
We seal before we insulate
Insulation slows heat moving through a surface. It does nothing about air moving through a hole, and in an oil-heated house the warm air escaping through the attic floor is air the boiler has already paid to heat, replaced by cold air drawn in through the rim joist and the basement.
In a 1950s East Islip house the order runs from the top. In the attic, close the chimney chase with metal and fire-rated sealant, seal the top plates, the plumbing stack, the bath fan and the ceiling fixtures, and weatherstrip the hatch. In a cape, block the joist bays under the knee walls and put an air barrier on the back of each knee wall. Baffle the eaves, then blow the attic floor to full depth. In the basement, seal and insulate the rim joist and close the pipe holes under the baseboards.
If a quote specifies a depth of insulation and never mentions air sealing, it is half a job.
What insulation costs in East Islip
Most of our projects run between $3,500 and $12,500. A 1960s ranch with one open attic sits near the bottom of that range. A 1950s cape with knee walls on both sides runs higher, and so does a boiler house whose heating loops must be traced and protected before a knee-wall space is closed in. A pre-1940 house with dense-packed walls and several attic sections can reach the top of the range or be done in stages.
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 East Islip
East Islip’s electricity comes from PSEG Long Island. Gas comes from National Grid, whose lines reach many of the hamlet’s streets but not all. The electric company sets the program lane, and a PSEG Long Island customer cannot use NYSERDA’s Comfort Home program.
PSEG Long Island’s lane begins with a free Whole House Energy Assessment, which includes a check of insulation and drafts, a thermal scan and a blower door test. For market-rate single-family homes it lists a $2,500 insulation rebate, a $1,000 air-sealing rebate and $500 for duct sealing, with higher amounts for income-qualified homes and homes in state-designated disadvantaged communities. Oil-heated homes are named as eligible, alongside gas, propane and electric. The insulation must go in with blower-door-assisted air sealing, and the rebates are paid through PSEG Long Island’s participating contractors, so ask any installer whether they are one before you sign.
National Grid’s Long Island insulation rebate program is not taking new applications, and income-eligible households go through EmPower+. For a Suffolk household under its 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 a household of four), or half the cost up to $7,000 at the moderate-income tier (below $131,900 for four), through an EmPower+ contractor. Owners and renters can apply, and Long Island households should check eligibility on the MyEnergy portal.
NYSERDA’s Green Jobs–Green New York program offers unsecured loans of $1,500 to $25,000 over 5, 10 or 15 years; PSEG Long Island customers apply for the on-bill version through PSEG Long Island. The federal insulation tax credit (Section 25C) ended for work placed in service after 31 December 2025, so a 2026 job carries no federal credit, and New York has no state tax credit for insulation. Our New York and New Jersey rebate guide sets out each program.
Code and climate in East Islip
86.7% of East Islip’s homes were built before 1980. New York’s first statewide energy code took effect on 1 January 1979, so every 1950s cape and 1960s ranch in the hamlet went up with no energy code behind it. Suffolk County is Climate Zone 4.
A house built new today follows the 2025 Energy Conservation Construction Code of New York State, in force since 31 December 2025: R-49 ceilings, or R-38 over the whole ceiling wherever it keeps full uncompressed height over the wall top plate at the eaves; R-30 floors; basement and crawl space walls at R-15 continuous, R-19, or R-13 plus R-5 continuous; U-0.27 windows; and no more than 3.0 air changes per hour at 50 pascals.
That table is for new construction. In an existing house, unaltered parts need not comply, and New York’s code does not require a blower door test when you insulate an existing home. When a renovation exposes wall or roof cavities, as when a pre-war kitchen wall comes down to the studs, those cavities must be insulated to full depth. ENERGY STAR recommends R-60 for an uninsulated attic in this zone, and R-49 for one that already holds 3 to 4 inches.
Common questions about insulation in East Islip
Do you install insulation in East Islip, NY?
Yes, from the streets near Heckscher State Park and the bay up to the Islip Terrace line. Most of our East Islip work is the 1950s cape and ranch, 36.3% of the hamlet, followed by the 1960s and 70s ranches and high ranches and the 814 houses from before 1940. We also work in the neighborhoods built on the old estate land, such as Deer Run, Country Village and Beecher Estates. Apartment buildings of fifty or more units are for their boards and owners to decide. Call and we will tell you where your house fits.
How much does insulation cost in East Islip?
Most projects run $3,500 to $12,500. A 1960s ranch with one attic and an open rim joist is usually near the low end. A 1950s cape costs more for its knee walls, eave joist bays and slopes. In a boiler-heated house, tracing the heating loops and keeping them on the warm side of the insulation adds time. A pre-1940 house is priced after we map its walls and attics, and a large one can be done in stages. The written price follows a free walk-through.
Are there insulation rebates in East Islip?
Yes, through the electric company. East Islip is PSEG Long Island territory, and 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. Oil-heated homes qualify. Comfort Home is not open to PSEG Long Island customers. Income-eligible owners and renters can apply to EmPower+, and Green Jobs–Green New York loans can cover more of a large job. The federal 25C credit has ended, and New York has no state credit.
Our East Islip house is drafty whenever the wind comes off the bay. Should we replace the windows first?
Usually not first. Wind pushes cold air in on the side it hits, but that air has to leave somewhere, and in most older houses the bigger openings are the attic floor, the chimney chase, the rim joist and the holes around pipes and wiring, not the window sashes. A blower door test shows where the air is really moving. Sealing those openings is usually the cheaper fix, and it calms the windy side of the house too. PSEG Long Island lists a window rebate only for a house also getting a whole-house cold-climate heat pump plus insulation and air sealing.
Free energy audit in East Islip
In an East Islip house we start in the basement: the boiler or furnace, where the heating pipes run, the rim joist and the base of the chimney. Then the attic floor, the chimney chase from above, the eaves and, in a cape, the space behind each knee wall. In a pre-1940 house we check the wiring and the wall cavities first. If the biggest loss is a chimney chase and a bare rim joist, we say so. The written scope and price are free, with no obligation.
Call 914-825-6824 or use our contact form. We are open 8am–8pm, seven days a week, 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 Islip
- Insulation in Sayville
- Insulation in Bay Shore
- Basement insulation
- Air sealing
- What happens during an energy audit