32.5% of Hazlet’s 7,800 housing units were built in the 1950s. That is 2,535 houses out of a single decade, and it explains almost everything about the work here. Add the 1960s and 70s, 39.5%, and 78.7% of the township was standing before New Jersey had an energy code at all. The median unit dates from 1965.
This is a township of houses, not buildings: 83.2% of units are detached, 88.5% of occupied units are owner-occupied, and only 5.3% of the stock has been built since 2000. 87.1% of homes heat with gas, 7.6% with electricity, 2.7% with oil and 2.0% with bottled gas. What that adds up to is a postwar tract house with an original attic, a gas bill in the owner’s name and nobody upstairs to ask for permission.
Hazlet was Raritan Township until a 1967 referendum renamed it, and before that it had already given away the land that became Holmdel, Aberdeen, Keyport, Keansburg and Union Beach. What was left filled in with subdivisions for people commuting to New York, and the older names survive as neighborhoods: Centerville, North Centerville, Mechanicsville, Tiltons Corner, Van Marters Corner, South Keyport and West Keansburg.
The houses we insulate in Hazlet
The 1950s cape and the 1950s ranch are the two houses this town is made of, and they fail in different places. The cape fails at the knee wall. Behind the upstairs bedrooms are two triangular attics, and the wall between them and the room is a short stud wall with batts held on the room side and open framing behind them, so it stops nothing. The floor joists run under that wall out to the eave, which lets outdoor air travel under the bedroom floor all winter. The rafter slopes have no baffle and often no room for insulation at all, and the flat attic over the second floor is shallow and shared with the dormer cheeks. Every one of those surfaces has to be dealt with as one air barrier, in one visit, or the upstairs stays uncomfortable.
The ranch fails across its ceiling. It has one long low attic, and after seventy years the original loose-fill has settled well below the top of the joists, drifted back from the eaves where the soffit vents blow across it, and left the top plates, the chimney chase, the plumbing stack, the attic hatch and the bath fan wide open. In a small house with a big footprint that plane is most of the heat loss. Sealing it and blowing it to depth is the single highest-return job in Hazlet and it is usually a one-day job.
The 1960s and 70s brought the split-level and the bi-level, 1,618 units in the 60s and 1,461 in the 70s. A split has two or three attic sections at different heights with knee walls between them, a bedroom over the garage sitting on joist bays that run out over the header, and a cantilevered bay at the front. A bi-level puts half the lower floor below grade against uninsulated block, with a family room that never warms up and a garage on the same level as living space. In both, the garage ceiling is the assembly most often skipped by whoever did the attic last time.
16.0% of the township is 1980s and 90s and only 5.3% is newer than 2000. Those houses have insulated walls already; what they have instead is a vented attic with ductwork in it, unbaffled cathedral slopes and recessed lights punched through the ceiling plane. And 4.8% of Hazlet, 374 units, predates 1940 — the older frame houses out at the corners, which we assume are balloon-framed with knob-and-tube until proven otherwise, and where the attic floor, cellar and rim come before anyone opens a wall.
The 592 mobile homes
7.6% of Hazlet’s housing is mobile and manufactured homes — 592 of them, against 1.1% across Monmouth County as a whole. No other town we write about here has that share, and the homes in it are nothing like the capes down the road, so they get scoped differently.
A manufactured home loses heat mostly through the floor and the belly. Under the floor there is a belly board holding a thin blanket of insulation, and by the time a home is thirty years old that board has usually torn, sagged or been opened by a plumber and never closed, so the insulation is on the ground and the ducts running through the belly are in outdoor air. The skirting is not insulation, and in most homes it does not seal either. The roof cavity is shallow, ventilated at the eave and often impossible to blow deep, and older units have a metal roof with a vapor barrier under it that decides what can safely go up there. Windows and doors leak at the frames.
The work that pays in one of these is the underside: repair and close the belly, insulate and seal the ducts inside it, air-seal the floor penetrations where the plumbing comes up, close the skirting line so wind stops washing the underfloor, and only then look at the ceiling. We say plainly when a home is too far gone in the belly to be worth the money. On the rebate side, the utility programs are written around a one- to four-unit home the owner lives in, and whether a home in a park qualifies is a question we put to the utility before the job rather than after.
We seal before we insulate
Insulation slows heat moving through a surface. It does nothing about air moving through a gap. Blow a Hazlet ranch attic to full depth over open top plates and a chimney chase and you have paid for material that the air simply goes around.
In a 1950s cape the sequence is fixed: block the floor joist bays at the eave line so air stops running under the bedroom floor, put a real air barrier on the back of both knee walls, seal the top plates, the plumbing chase and the bath fan and duct it outside, baffle the rafter slopes so they can be filled without choking the soffit, then insulate the knee walls, the slopes and the flat attic as one system, then the rim joist in the cellar. In a ranch it is the top plates, cans, chases and hatch first, then baffles, then depth. In a split or bi-level, the garage ceiling and the block wall of the lower level come with it.
If a quote specifies a depth of insulation and never mentions air sealing, it is half a job.
What insulation costs in Hazlet
Most of our projects run between $3,500 and $12,500. The postwar footprints here are modest, so the number tends to sit low in that band. In a cape it moves with the feet of knee wall and eave to be blocked and whether the rafter slopes are filled. In a ranch it is attic area and the number of penetrations. In a split it is the count of attic levels, the garage ceiling and the cantilever. In a manufactured home it is the state of the belly and how much duct is running through it. Our spray foam cost page covers the foam side of the number.
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. After air sealing and insulating, homeowners typically save 20% or more on heating and cooling.
Insulation rebates in Hazlet
Gas here is New Jersey Natural Gas and electricity is JCP&L. With 87.1% of the township on gas heat, the gas utility is where nearly every Hazlet homeowner should start, since the gas program requires gas heat; the 7.6% heating with electricity start with JCP&L instead. A house can go through either utility’s program, and the contractor’s approvals usually decide which one leads.
New Jersey Natural Gas Whole Home Energy Solutions, sold under the SAVEGREEN name, pays up to $7,500 in rebates on a project: $2,000 at a modeled five percent energy saving, then $200 for every percentage point above that, capped at $7,500 and at half the project cost, with 0% on-bill repayment of up to $25,000 available alongside it. Insulation and air sealing must both be part of the job, and the work has to be installed by June 30, 2027. New Jersey Natural Gas also gives its residential customers a free Whole Home Energy Assessment once every twelve months, which is a separate, lighter walk-through with small items installed on the spot.
JCP&L Whole Home Energy Solutions runs the same formula to the same $7,500 ceiling and offers 0% on-bill financing of $2,500 to $25,000 over 36, 60 or 84 months up to $10,000, or 120 months above that and for income-qualified customers. The audit is performed by a contractor participating in the program and JCP&L does not publish its price. JCP&L’s own free Whole Home Energy Assessment is open to residential customers who own the home.
Below those sit the no-cost programs. New Jersey Natural Gas Home Weatherization installs up to $14,000 of insulation and air and duct sealing at no charge for income-qualified heating customers who have owned the home at least a year. JCP&L Home Weatherization for Income-Qualified Customers covers up to $14,000 of upgrades plus $2,500 of health and safety repairs for households between 250% and 400% of the federal poverty guidelines. New Jersey Comfort Partners does the work at no cost at or below 250% of the guidelines, $82,500 a year for a family of four; the 2.7% of Hazlet on oil and the 2.0% on bottled gas are referred to the state’s weatherization office instead.
New Jersey’s IRA Home Energy Rebates have not launched — the state’s page says they are in development and not open for applications. The federal Section 25C tax credit ended for anything placed in service after 31 December 2025, so nothing on a 2026 job earns a federal credit no matter who tells you otherwise. The current picture is in our New Jersey rebate guide.
Code and climate in Hazlet
78.7% of Hazlet went up before 1980, and therefore before New Jersey’s first statewide energy subcode of 1 January 1978. That is the highest pre-code share among the Monmouth towns we cover, and it is not an abstraction: the 1950s cape was built with no requirement to insulate anything, and what it has is whatever the builder felt like buying. Monmouth County is climate zone 4A.
New Jersey adopted the 2024 IECC on 17 August 2026. New construction now gets R-49 ceilings — the 2021 edition it replaced called for R-60, and a complete permit application filed under the old code is still accepted until about 16 February 2027 — with walls at R-30 in the cavity or R-20 plus R-5 continuous, windows at U-0.30, and air leakage no greater than 3.0 air changes per hour at 50 pascals. A 1955 cape with batts in the knee wall is not in the same conversation. R-49 is the number the state considers right for this climate, and it is what we design to in a retrofit.
A standing house is governed by New Jersey’s Rehabilitation Subcode, which does not ask you to bring the whole house to current code to improve one part of it, and does not require a blower-door test. Blown-in or batt insulation against the interior finish is ordinary maintenance with no permit. Spray foam and other foam plastic insulation require a permit, which we pull as part of the job.
Common questions about insulation in Hazlet
Do you install insulation in Hazlet, NJ?
Yes, and most of it is the postwar tract house. 32.5% of the township is 1950s and 39.5% is 1960s and 70s, so the daily work is cape knee walls and eave joist bays, ranch attic planes, split-level garage ceilings and cantilevers, and bi-level lower levels against block. We also insulate the manufactured homes, which are 7.6% of the stock here, and the pre-1940 frame houses out at the old corners.
How much does insulation cost in Hazlet?
Most projects run $3,500 to $12,500, and postwar Hazlet houses tend to land in the lower half of that. In a cape the drivers are the feet of knee wall and eave to block and whether the slopes are filled. In a ranch it is attic square footage and penetrations. In a split, add the garage ceiling and the cantilever. In a manufactured home it is the belly and the ducts in it. Price and scope come in writing after a free walk-through.
Are there insulation rebates in Hazlet?
Yes. New Jersey Natural Gas is the gas utility and JCP&L the electric one, and each runs Whole Home Energy Solutions: up to $7,500 in rebates toward air sealing and insulation, with 0% repayment of up to $25,000 alongside it, through a contractor participating in the program. With 87.1% of the township on gas heat, most people here start with New Jersey Natural Gas. Income-qualified households can get the work at no cost through the weatherization programs or Comfort Partners. New Jersey’s IRA rebates have not launched and the federal 25C credit is over.
The upstairs bedrooms in our Hazlet cape are freezing in winter and baking in summer. What actually fixes that?
Air, not inches. In a cape the bedroom is surrounded by unconditioned attic on four sides: two knee-wall attics, the rafter slopes and a shallow flat above. Outdoor air runs in at the eave, under the bedroom floor and up behind the knee walls, so batts stapled to the room side never had a chance. The fix is to block the joist bays at the eave, air-seal and insulate the back of the knee walls, baffle and fill the slopes, and treat the flat as part of the same envelope. Done together, that room becomes usable in both seasons.
Free energy audit in Hazlet
We go into the knee-wall attics behind the upstairs bedrooms, check the eave line and the slopes, and measure what is actually on the flat. In a ranch we walk the whole plane and look for drift, open chases, uncapped cans and a bath fan venting into the insulation. In a split we look at the garage ceiling, the cantilever and each attic level. In a manufactured home we start under the floor. Then the cellar, the rim and any ducts outside the insulation, and you get a written scope and a price. No charge, no obligation.
Call 914-825-6824 or send the form below. Open 8am–8pm, seven days. We work out of New Rochelle, NY with a 100-plus in-house crew, and we hold manufacturer installer certifications from the spray foam manufacturers we use.
Learn more
- Insulation contractors across Monmouth County
- Insulation contractors in Middletown
- Insulation contractors in Holmdel
- Insulation contractors in Freehold Township
- New Jersey insulation rebates in full
- Attic insulation and air sealing
- Insulating an older home