85.3% of the occupied homes in Mastic Beach heat with fuel oil. Electricity heats 8.0%, bottled gas 2.6% and utility gas only 2.0%, because Mastic Beach has little or no utility gas service. Nearly every house in the hamlet burns oil, and that decides the economics of every job here: the heat a house loses is heat bought by the gallon, and for most homes there is no gas main to switch to.
Mastic Beach is a hamlet in the southeastern part of the Town of Brookhaven, on the South Shore, on a peninsula extending into Moriches Bay, near Smith Point County Park and the Fire Island National Seashore. Of its 5,509 homes, 96.4% are detached houses, 82.5% of occupied homes are owner-occupied, and the median home was built in 1971.
The stock is older than the median suggests: 28.6% of it dates from the 1940s and 50s and another 5.8% from before 1940, while the 1960s and 70s account for 38.9%. The work is mostly small houses, raised ranches and the additions that have grown onto both.
The houses we insulate in Mastic Beach
The 1970s built 1,366 homes, 24.8% of the stock and the largest single decade. Many are raised ranches and ranches. A raised ranch has its bedrooms over a lower level that sits partly in the ground, and its losses are predictable: a long attic with thin, settled loose-fill and open top plates; a rim joist sitting bare on the foundation; a garage ceiling under a bedroom; and a foundation wall standing a few feet out of the ground with nothing on it. A ranch has the same attic and, often, a crawl space or a low basement under the floor.
The 1940s left 682 homes and the 1950s 894, together 28.6% of the hamlet, with 321 more built before 1940. Many are small houses: one story or a story and a half, low roofs, shallow attics that pinch to nothing at the eaves, and floors framed over crawl spaces or low foundations. Their walls are often empty. Houses of that size are often added onto, a room on one side, a dormer on top, a porch closed in, and each addition has its own floor, its own roof and a seam where it meets the original house.
The 1960s added 14.1% of the stock and the 1980s 11.1%. Those houses have some wall insulation and an attic of original, settled material. 10.0% has been built since 2000, including 93 homes from 2020 on; those have full walls, and their weak points are the attic hatch, the ducts and the bath fans.
At 85.3% oil, payback here is measured in deliveries. A house that loses less heat runs its burner less and needs fewer fills, and in a hamlet without gas mains that saving continues for as long as the house stays on oil. If a heat pump is in the future, sealing and insulating first means a smaller unit can heat the house, and it will not struggle on the coldest nights.
Fixing up a Mastic Beach house: insulate while it is open
Mastic Beach voted to incorporate as a village in 2010. Petitioners argued that the Town of Brookhaven was not doing enough code enforcement on blighted streets and eyesore buildings, and the village was to take up building code enforcement. Residents voted 1,922 to 1,215 in November 2016 to dissolve it, and on 1 January 2018 the hamlet returned to the Town of Brookhaven’s care. Either way, houses get fixed up one at a time, and when a Mastic Beach house is being renovated, that is the cheapest moment it will ever have to be insulated.
New York’s code already points the same way. When an alteration exposes wall or roof cavities, the exposed cavities have to be insulated to full depth with material of at least R-3 per inch, and existing insulation cannot be reduced. So a wall with the drywall off gets filled before it is closed, and the question is only what goes in.
In an older 2×4 wall we usually recommend open cell foam or dense-packed cellulose filling the cavity, with the wiring checked first, because a wall is opened once. Where the wall faces a damp crawl space or a bathroom, closed cell foam, which acts as a vapor retarder, is the better choice. A ceiling taken down under a shallow attic is the chance to air-seal the top plates and the light boxes from below and to get closed cell foam into the tight eave that could never be reached from the attic side. A floor opened over a crawl space gets its bays sealed at the rim and filled, or the crawl space walls insulated instead.
Two mistakes to avoid. Do not close a renovated wall around a bath fan or range hood that dumps into the attic or the wall; vent it outdoors first. And do not bury old wiring in insulation until an electrician has looked at it.
We seal before we insulate
Insulation slows heat through a material; it does not stop air. In an oil-heated house, air leaking out of the attic is heat the burner already made, and air leaking in at the sill is cold the burner has to make up.
In a Mastic Beach raised ranch the order is: seal the attic top plates, plumbing vent, bath fan housing, light boxes and hatch; close the gap at the oil burner’s chimney with sheet metal and high-temperature sealant, never foam; set baffles at the eaves; then fill the attic floor. Downstairs, seal the sill, insulate the rim joist, seal and fill the garage ceiling, and insulate the exposed foundation wall where the lower level is lived in. In a small 1940s or 50s house the crawl space or the floor usually comes first. After any tightening, keep the burner’s combustion air supply and have its draft checked.
If a quote specifies a depth of insulation and never mentions air sealing, it is half a job.
What insulation costs in Mastic Beach
Most of our projects run between $3,500 and $12,500. A small post-war house with one shallow attic is often at the lower end, though a pinched eave may need closed cell foam. A 1970s raised ranch usually prices in the middle of the range, since the attic, the rim, the garage ceiling and the half-buried foundation wall are all part of it. A house with a crawl space, empty walls and additions under separate roofs runs higher, because each is its own piece of work. During a renovation, filling open walls costs less than it ever will again. For foam numbers, 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 Mastic Beach
The electric company in Mastic Beach is PSEG Long Island, and the hamlet has little or no utility gas service. NYSERDA’s Comfort Home program does not cover PSEG Long Island homes, so it is not an option here.
PSEG Long Island’s rebates are the main route. After a free Whole House Energy Assessment, which checks insulation and drafts and includes a thermal scan and a blower door test, it lists a $2,500 insulation rebate and a $1,000 air-sealing rebate for market-rate single-family homes, with higher amounts for income-qualified homes and homes in state-designated disadvantaged communities. Oil heat is no obstacle: PSEG Long Island’s rules name oil alongside natural gas, propane and electric heat. What it does insist on is comprehensive, blower-door-assisted air sealing done together with the insulation, by one of its own participating contractors, so look the contractor up on its list before signing.
NYSERDA’s EmPower+ helps income-eligible owners and renters of one- to four-family homes, through an EmPower+ contractor. For a Suffolk household of four at or below $98,925 a year, air sealing and insulation can be done at no cost up to $14,000; below $131,900, it pays half the cost up to $7,000, and federal HEAR funds can add up to $1,600 for air sealing, insulation and ventilation. The median household income in Mastic Beach is $109,381, so the limits are worth checking. Long Island households should check eligibility on the MyEnergy portal.
Two more. PSEG Long Island’s REAP program gives a free in-home energy survey to customers at or below $131,900 for a household of four with no REAP visit in the past five years, and can install door sweeps, attic hatch covers and a smart thermostat at no cost, though not insulation. And NYSERDA’s Green Jobs–Green New York loans run $1,500 to $25,000 over 5, 10 or 15 years for energy work in an existing home; they are paid back, and extensive gut rehabilitation is not eligible. 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 New York and New Jersey rebate guide.
Code and climate in Mastic Beach
73.4% of Mastic Beach homes were built before 1980. Its post-war houses and most of its 1970s raised ranches went up before New York’s first statewide energy code took effect on 1 January 1979. Suffolk County is Climate Zone 4.
New homes are held to the 2025 Energy Conservation Construction Code of New York State, in effect since 31 December 2025: R-49 in the ceiling, with R-38 accepted over the whole ceiling where its full uncompressed height continues over the wall top plate at the eaves; R-30 floors; R-15 continuous, R-19, or R-13 plus R-5 continuous on basement and crawl space walls; U-0.27 windows; and no more than 3.0 air changes per hour at 50 pascals.
A renovation is not a new house. The code leaves the parts you are not altering as they are, and New York’s code does not require a blower door test when you insulate an existing home; the rule that does apply is the full-depth fill of any cavity the work exposes. For the attic, ENERGY STAR recommends R-60 if it is uninsulated and R-49 if 3 to 4 inches are already there.
Common questions about insulation in Mastic Beach
Do you install insulation in Mastic Beach, NY?
Yes. Most of our Mastic Beach work is the 1970s raised ranch, 24.8% of the hamlet, and the small houses of the 1940s and 50s, 28.6%: attics, rim joists, garage ceilings, crawl spaces and empty walls, plus the additions built onto them. We also insulate houses mid-renovation while the walls are open, and newer homes with attic and duct problems, anywhere on the peninsula.
How much does insulation cost in Mastic Beach?
Most projects run $3,500 to $12,500. A small post-war house with one shallow attic tends toward the low end. A 1970s raised ranch is mid-range once its attic, rim, garage ceiling and foundation wall are counted. A house with a crawl space, empty walls and additions under separate roofs costs more because each is its own job. Open walls during a renovation are the cheapest walls to fill. The written scope and price follow a free walk-through.
Are there insulation rebates in Mastic Beach?
Yes, mainly from PSEG Long Island, the hamlet’s electric company. It lists $2,500 for insulation and $1,000 for air sealing in a market-rate single-family home, more if the household is income-qualified, paid through its participating contractors once a free Whole House Energy Assessment is done. Oil heat is no bar. Comfort Home is not open to PSEG Long Island customers. Income-eligible owners and renters can check EmPower+ on the MyEnergy portal. The federal 25C credit ended with 2025, and New York has no state insulation credit.
Our Mastic Beach house sits over a crawl space. Do we insulate the floor or the crawl space walls?
It depends on what is down there. If the crawl space holds the oil line, water pipes or ducts, or has solid walls, we usually seal the vents and the sill, cover the ground with a vapor retarder and insulate the crawl space walls, so the space stays above freezing and the floor sits inside the house. If it is open, on piers or badly vented, we insulate and air-seal the floor from below instead, with a rigid barrier under the joists. A crawl space with standing water is fixed before either.
Free energy audit in Mastic Beach
In a raised ranch we start in the attic at the eaves, top plates and hatch, then go down for the sill, the rim joist, the garage ceiling and the exposed foundation wall. In a post-war house we get into the crawl space and look at every addition’s seam and roof. If you are renovating, we look at what will be opened and when. We check the oil burner’s air supply before recommending any sealing. Then we put the scope and price in writing, at no charge and with 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 Mastic
- Insulation in Shirley
- Crawl space insulation
- Wall insulation during a renovation
- Insulating older homes