Electricity heats 16.5% of the occupied homes in St. James. Utility gas heats 43.0% and fuel oil 36.5%, so the hamlet has three fuels in real numbers, and the electric share is the one that changes the math: every draft in an electrically heated house shows up on the electric bill. St. James has 5,095 homes, 87.2% of occupied homes are owner-occupied, and the median home dates from 1969.
St. James is a hamlet on the North Shore, in the eastern part of the Town of Smithtown, east of the hamlet of Smithtown. The Village of Head of the Harbor and Stony Brook Harbor lie to its north, and the main campus of Stony Brook University sits immediately to its east. Its housing is mostly detached, 75.2%, but 11.1% is single-family attached, 566 townhouses and duplex halves, and 8.4% sits in buildings of five to nine units.
The ages are spread wide: 7.3% before 1940, 19.7% in the 1940s and 50s, 41.8% in the 1960s and 70s, and 24.1% in the 1980s and 90s. That last figure shows up in the work as vaulted ceilings, skylights and attached homes.
The houses we insulate in St. James
The 1960s are the largest decade, 1,243 homes and 24.4% of the stock, and the 1970s added 885 more. Those are ranches, splits and center-hall colonials. The ranch has one long attic where the original batts have slumped and the ceiling below is cut through for lights, fans and the plumbing stack. The split has a bedroom wing whose side wall faces the attic over the lower level, framed like an outside wall but left open on the attic side. The colonial has a second floor that sometimes overhangs the first, with the floor joists running out past the wall into a soffit that lets outdoor air under the front bedrooms.
The 1950s built 810 homes, 15.9% of the stock: capes and smaller ranches. A cape’s cold rooms are upstairs, where the bedrooms tuck under the roof behind knee walls that have insulation on one face and none on the other, and the floor bays under those walls run open to the eave.
The 1980s built 840 homes, 16.5%, and the 1990s another 388. Their walls are insulated. What fails in them is overhead: a family room with a vaulted ceiling and no room for insulation plus ventilation between drywall and roof deck, skylight shafts framed through the attic with thin batts on their sides, a two-story entry with an attic behind its upper wall, and air conditioning ducts running through the attic. A house of that era on electric heat pays for all of it at the meter.
The attached homes are their own case. A townhouse’s party walls are shared, its roof is often continuous across the row, and the attic may belong to an association rather than the owner. Electric heat is often found in attached homes of the 1970s and 80s, and in an end unit the exposed side wall and the attic above it carry most of the loss. We insulate what the owner controls, and we tell you plainly when the attic or the roof belongs to the board.
The Saint James District: older houses along North Country Road
In the early 20th century St. James was a popular vacation spot for stage and screen names; summer residents included Lionel, Ethel and John Barrymore, Buster Keaton, Myrna Loy and Irving Berlin, and the architect Stanford White is among the hamlet’s noted residents. The St. James General Store on Moriches Road, said to be the oldest continuously operating general store in the country, was added to the National Register of Historic Places in 1973 with other historic structures as part of the Saint James District. Many of those 19th-century buildings stand along Route 25A, North Country Road, and the St. James station-house, opened in 1873, is the second-oldest on the Long Island Rail Road. 371 homes in the hamlet predate 1940.
Owners of an old frame house here usually want it to keep exactly the look it has, and insulation can be done without changing that. The attic comes first: seal the tops of the wall cavities and the chimney, then insulate the attic floor, or the rafters if the attic is used, keeping any original board floor. The cellar comes next: seal the sill and insulate the rim joist from inside. The walls come last and only where it makes sense, filled from inside where plaster is being repaired anyway, or through a course of siding lifted and put back, never through holes drilled in original clapboard or trim.
Two more points for these houses. Old wood sash windows can stay: a tight interior or exterior storm window cuts much of their draft without replacing them. And an old frame wall dries in both directions, so we use vapor-open materials in it, such as dense-packed cellulose, rather than sealing it with closed cell foam from the inside.
We seal before we insulate
Insulation slows heat conducted through the ceiling, walls and floor. Air leaks go around it, and in a house heated by electric baseboards the air leaking out through a skylight shaft is paid for on the next PSEG Long Island bill.
In a St. James colonial of the 1980s the order is: in the attic, seal the top plates, the chimney chase with sheet metal and fire-rated sealant, the bath fan housings, the recessed light housings and the attic stair; seal the skylight shafts where they pass through the attic and wrap them in insulation; air-seal the attic side of the two-story entry wall and insulate it; seal and insulate any ducts in the attic; then bring the attic floor to depth. Last, the rim joist in the basement.
If a quote specifies a depth of insulation and never mentions air sealing, it is half a job.
What insulation costs in St. James
Most of our projects run between $3,500 and $12,500. A 1960s ranch with one open attic sits near the lower end. A 1980s house with vaulted ceilings and skylight shafts runs higher, because a vaulted ceiling with no attic above it often has to be insulated from the roof side or with closed cell foam, and each shaft is sealed separately. A townhouse depends on what the owner controls. An old house near North Country Road that keeps its exterior untouched costs more per wall than a house with vinyl siding. Spray foam costs are laid out separately.
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 St. James
PSEG Long Island supplies the electricity in St. James, and National Grid the gas where its lines reach, which is many streets but not every one; the bill tells you which you have. That electric company rules out NYSERDA’s Comfort Home program, which does not serve PSEG Long Island homes.
PSEG Long Island’s own offer starts with a free Whole House Energy Assessment, done by a participating contractor, covering insulation and drafts, a thermal scan and a blower door test. It lists $2,500 for insulation and $1,000 for air sealing in a market-rate single-family home, plus $500 for duct sealing, with higher amounts for income-qualified homes and homes in state-designated disadvantaged communities. Electric-heated houses are eligible alongside oil, gas and propane. Insulation must be paired with comprehensive, blower-door-assisted air sealing, and all ductwork in unconditioned space must be sealed. The list is written for single-family homes, and the rebates are paid only through PSEG Long Island’s participating contractors, so ask before you sign whether yours is one.
For income-eligible households, NYSERDA’s EmPower+ covers air sealing and insulation in one- to four-family homes, for owners and renters, through an EmPower+ contractor: at no cost up to $14,000 where Suffolk household income is at or below $98,925 for four, or half the cost up to $7,000 below $131,900 for four, with up to $1,600 more in federal HEAR funds. Long Island households should check eligibility on the MyEnergy portal. National Grid’s Long Island insulation rebates are not accepting new applications.
PSEG Long Island’s REAP program offers a free in-home energy survey to customers at or below its income guideline, $131,900 for a household of four, with no REAP visit in the last five years; it can install a smart thermostat, door sweeps, attic hatch covers and LED bulbs at no cost, but not insulation. The federal Section 25C credit ended for work placed in service after 31 December 2025, and New York has no state tax credit for insulation. See our rebate guide for New York and New Jersey.
Code and climate in St. James
68.7% of St. James homes were built before 1980. The houses of the Saint James District, the 1950s capes and the 1960s and 70s ranches and colonials were built before New York’s first statewide energy code took effect on 1 January 1979. Suffolk County is Climate Zone 4.
Since 31 December 2025, new construction follows the 2025 Energy Conservation Construction Code of New York State. Its numbers: R-49 in the ceiling, or R-38 across the full ceiling where that R-38 keeps its full uncompressed height over the wall top plate at the eaves; R-30ci where all the insulation sits above the roof deck; 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 skylights at U-0.50; and air leakage no higher than 3.0 air changes per hour at 50 pascals.
A standing house is not pulled up to those numbers. The unaltered parts of an existing home need not comply, and New York’s code does not require a blower door test when you insulate an existing home. If a renovation opens a vaulted ceiling or a wall, the exposed cavities must be insulated to full depth. In an attic, ENERGY STAR recommends R-60 if it is uninsulated and R-49 if it already holds 3 to 4 inches.
Common questions about insulation in St. James
Do you install insulation in St. James, NY?
Yes. Most of our St. James work is the 1960s and 70s ranches, splits and colonials, 41.8% of the hamlet, and the 1980s and 90s houses with vaulted rooms, skylights and attic ducts. We also insulate the 1950s capes, townhouses where the owner controls the attic, and the older frame houses near North Country Road without changing their exteriors. Nearby Smithtown and Stony Brook have their own pages.
How much does insulation cost in St. James?
Most projects run $3,500 to $12,500. A 1960s ranch with one open attic is near the low end. A 1980s house with vaulted ceilings and skylight shafts costs more, since a vaulted ceiling may need work from the roof side and every shaft is sealed on its own. A townhouse is priced on what the owner controls. An older house whose clapboard stays untouched costs more per wall. The written scope and price follow a free walk-through.
Are there insulation rebates in St. James?
Yes. St. James is PSEG Long Island territory. PSEG Long Island lists $2,500 for insulation and $1,000 for air sealing in market-rate single-family homes, more for income-qualified homes, paid through its participating contractors after a free Whole House Energy Assessment. Electric-heated homes qualify. Comfort Home is not offered to PSEG Long Island customers. Income-eligible owners and renters can check EmPower+ on the MyEnergy portal. The federal 25C credit has ended, and New York has no state insulation credit.
Our 1980s St. James house has a vaulted family room with skylights, and it is hot in summer and cold in winter. Why?
Three reasons, usually together. A vaulted ceiling has only the rafter depth for insulation, often a single batt with no vent space, so it runs thin and wind-washed. The skylight shafts pass through the attic with thin batts on their sides and gaps at the top, so attic air reaches the room. And the skylights themselves lose more heat than the wall. We seal and insulate the shafts from the attic, and where the vault is thin, add closed cell foam when the ceiling or roof is opened.
Free energy audit in St. James
In a 1980s house we start in the attic, at the skylight shafts, the back of the two-story wall, the ducts and the top plates, then look at the vaulted ceilings from below and the rim joist in the basement. In a 1960s house the attic and the rim come first. In a townhouse we find out what you control before we price anything. In an older house near North Country Road we look at the attic, the cellar and the windows before the walls. You get the scope and price in writing, free and without 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 Smithtown
- Insulation in Stony Brook
- Insulation in Nesconset
- Insulating older homes
- Roof insulation for vaulted ceilings
- Air sealing