43.5% of Commack’s 11,915 homes went up in a single decade, the 1960s, and another 28.7% in the 1950s. Only 1.1% predates 1940, only 2.3% has been built since 2000, and the median home dates from 1964. 92.6% of the stock is detached houses and 93.7% of occupied homes are lived in by their owners. Commack is a hamlet of split-levels, high ranches and post-war ranches, most now past sixty and many still carrying the insulation they were built with.
Commack has no government of its own. Most of the hamlet lies in the Town of Smithtown and part in the Town of Huntington, and the town line changes nothing about an insulation job: both sides buy electricity from PSEG Long Island, and most of Commack is on National Grid gas lines. 72.6% of occupied homes heat with utility gas, 21.3% with fuel oil and 4.7% with electricity. In a gas-heated split-level the case is the winter gas bill and the upstairs bedroom that never holds a temperature, and both usually trace back to the same few gaps.
The houses we insulate in Commack
The Secatogue called the center of the island Winnecomac, “pleasant lands,” and from its earliest days Comac, as it was first spelled, was farmland with fertile soil. The farm era left little housing: 1.1% of today’s homes predate 1940. The Commack Methodist Church, built in 1789 as the Comac Church, and the Harned Brothers Sawmill of the 1840s, the only circular sawmill still operating on Long Island, are older than almost every house around them. In the few old farmhouses we assume balloon framing until we have looked, and nothing is blown into a wall that still carries knob-and-tube.
The 1950s left 3,415 homes, mostly one-story ranches and capes. A ranch of that decade has a long, low attic where the loose-fill has settled to a few inches and thins to almost nothing at the eave, because the roof meets the wall plate with no room to spare. Its leaks sit in predictable places: the dropped soffit over the kitchen cabinets, often open to the attic from above; the plumbing wall; the flue; the ceiling fixtures; and a pull-down stair with no weatherstrip and no cover.
The 1960s left 5,185 homes, and the split-level is the signature house of that decade here. A split stacks a bedroom level over the garage or family room, sets the living room and kitchen half a flight lower under their own roof, and sometimes adds a basement below. Each roof has its own attic, and the two attics are not the same kind of space. We come back to the split below, because it explains more Commack comfort complaints than any other assembly in the hamlet.
The high ranch is the other house of the 1960s and 70s: a split entry, a main floor up half a flight, and a lower level half in the ground with the garage tucked under the bedrooms. Its weak points are the rim joist, which sits at about eye level in the lower family room; the garage ceiling, with bedrooms on the other side of the joists; and, where the upper floor was pushed out past the lower wall, a cantilever whose underside is a thin soffit board over open joist bays. The attic above is one long plane, simple once it is sealed.
The 1980s and 90s added 13.4% of the stock, mostly larger colonials with code-minimum walls, the air handler and ductwork in the attic, and a bonus room over the garage. There the walls are not the job; the ducts, the recessed lights and the bonus room floor are. Townhouses are 2.8% of Commack’s units, so nearly every job here is one house with one owner.
Split-levels and the wall that faces the attic
Climb into the lower attic of a Commack split, the small space over the kitchen and living room, and look toward the bedroom level. That wall faces outdoor air on the attic side but was framed and finished like a partition. It usually holds a paper-faced batt leaning in each bay, open at the top and loose at the bottom, with the bedroom drywall as the only air barrier. Where the lower ceiling meets that wall, the stud bays often continue down into the wall between the living room and the bedroom level, so attic air has a path into the middle of the house.
That is why the upper level of a split runs cold in January and hot in July while the thermostat on the main floor reads fine. A split also stacks its levels on one open stair, and warm air rises up it and out through every gap at the top: fixtures, hatch, top plates, bath fan. More depth in the upper attic helps less than expected while that wall is still open.
The fix is specific. In the lower attic we seal the top of each open bay, fill the wall, and cover its attic side with rigid board, or closed cell foam where the space is too tight for anything else. Then both attic floors, the lower-level rim and the garage ceiling. Some Commack splits have no access to the lower attic at all; there we cut and frame a hatch as part of the scope.
We seal before we insulate
Insulation resists heat conducted through a ceiling or a wall. It does not stop air, and air moving through a gap carries heat straight past it. A split-level, with its open stair and several ceiling heights, pulls that air upward all winter.
In a Commack split the order is: seal the open bays and the attic side of the wall above the lower roof; seal the flue, plumbing stacks, bath fans and fixture boxes in both attic floors; weatherstrip the hatches; seal the garage ceiling and the lower-level rim. Then insulate, level by level. In a high ranch the order is the long attic plane first, then the rim, the garage ceiling and the cantilever.
If a quote specifies a depth of insulation and never mentions air sealing, it is half a job.
What insulation costs in Commack
Most of our projects run between $3,500 and $12,500. In Commack the number moves with how many separate attics the house has, and a split usually has two; whether the lower one has an access or needs one cut; how much of the attic-side wall has to be sealed and covered; and whether the garage ceiling and lower-level rim are in the scope. A 1950s ranch with one open attic sits toward the lower end. For the foam side of the number, see what spray foam costs.
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 Commack
On both sides of the Smithtown and Huntington line, Commack’s electric company is PSEG Long Island and its gas company is National Grid, which serves most of the hamlet. The electric company sets the rebate lane, and because it is PSEG Long Island, NYSERDA’s Comfort Home program is not available to Commack homes.
PSEG Long Island lists a $2,500 insulation rebate and a $1,000 air-sealing rebate for market-rate single-family homes, and $500 for duct sealing, with higher amounts for income-qualified homes and homes in state-designated disadvantaged communities. The money is paid through PSEG Long Island’s participating contractors after a free Whole House Energy Assessment, which covers a check of insulation and drafts, a thermal scan and a blower door test. Gas-heated and oil-heated houses both qualify. Two rules matter in a split-level: insulation must go in with comprehensive, blower-door-assisted air sealing, and all ductwork in unconditioned space must be duct sealed.
National Grid’s Long Island insulation rebate program is not taking new applications; income-eligible households go through EmPower+. If your household income is under Suffolk’s EmPower+ limit, NYSERDA’s EmPower+ program can pay for air sealing and insulation — at no cost up to $14,000 for lower-income households (at or below $98,925 for a family of four), or half the cost up to $7,000 for moderate-income households (below $131,900 for four) — through an EmPower+ contractor, plus up to $1,600 in federal HEAR funds for air sealing, insulation and ventilation. Long Island households should check eligibility on the MyEnergy portal. Each program pays only through its own contractors, so confirm before you sign.
The federal insulation tax credit (Section 25C) ended for work placed in service after 31 December 2025, so there is no federal insulation credit on a 2026 job, and New York has no state tax credit for insulation. The rest is in our New York and New Jersey rebate guide.
Code and climate in Commack
84.3% of Commack’s homes were built before 1980. New York’s first statewide energy code took effect on 1 January 1979, so most of the hamlet’s ranches and splits were built with no statewide energy code behind them. Suffolk County is Climate Zone 4.
The 2025 Energy Conservation Construction Code of New York State has been in force since 31 December 2025. For a new house it requires R-49 ceilings, or R-38 across the whole ceiling where the full height of uncompressed R-38 reaches 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; windows at U-0.27; and air leakage of no more than 3.0 air changes per hour at 50 pascals.
An existing Commack house is not held to that table. Unaltered parts do not have to comply, so insulating the attics of a split does not pull its walls or windows into the new-home standard, and New York’s code does not require a blower door test when you insulate an existing home. Where an alteration opens roof or wall cavities, the exposed cavities must be insulated to full depth. ENERGY STAR recommends R-60 for an uninsulated attic in this zone, or R-49 where 3 to 4 inches are already down, and that is the depth we design the attic floors to.
Common questions about insulation in Commack
Do you install insulation in Commack, NY?
Yes, on both sides of the Smithtown and Huntington town line. Most of our Commack work is the 1960s split-level and high ranch, 43.5% of the hamlet’s homes, and the 1950s ranches and capes before them: settled attic floors, the attic-side wall of the bedroom level, the lower-level rim, the garage ceiling and the cantilever. We also do the 1980s and 90s colonials with air handlers in the attic, and the few farmhouses left from Commack’s farming days.
How much does insulation cost in Commack?
Most projects run $3,500 to $12,500. A 1950s ranch with one open attic sits toward the lower end. A split-level costs more because it has two attics, sometimes one with no access, plus the wall between them, the garage ceiling and the rim in the lower family room. A later colonial is priced on its ductwork, the bonus room floor and the attic plane. We give a written scope and price after a free walk-through of the house.
Are there insulation rebates in Commack?
Yes. Commack is PSEG Long Island for electricity, 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. Comfort Home is not open to PSEG Long Island homes. Income-eligible households can apply to EmPower+. The federal 25C credit ended for work placed in service after 31 December 2025, and New York has no state insulation tax credit.
The bedrooms in our Commack split-level are cold in winter and hot in summer. Is that an insulation problem?
Usually it is an air problem first. The bedroom level of a split has a wall facing the lower attic that was built like an inside partition, often with loose batts and open bays, and warm air rises up the open stair and leaks out through the upper ceiling. More insulation on the top attic floor alone rarely fixes it. Sealing and covering that wall, sealing both attic floors and then insulating them usually does. We check the lower attic first, and if it has no access we tell you.
Free energy audit in Commack
In a Commack split we start in the lower attic, if there is a way in, and the wall that faces it; then the upper attic floor, the hatches and the flue; then the rim, the garage ceiling and any cantilever. In a high ranch or a colonial the time goes to the attic plane, the ducts and the garage. If the attic floors are fine and the loss is one open wall, we say so. Then a written scope and a price. No charge, no obligation.
Call 914-825-6824 or use our contact form. Open 8am–8pm, seven days. We 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 East Northport
- Insulation in Dix Hills
- Insulation in Kings Park
- Air sealing the gaps a split-level hides
- Insulating the ceiling over a garage
- Attic insulation