The Home Insulators

Insulation Contractors in Somerville, NJ

80.9% of Somerville’s housing went up before 1980 and the median unit dates from 1958. Nowhere else in Somerset County is the stock this old: 25.1% of the borough predates 1940, 28.6% is 1940s and 50s and 27.2% is 1960s and 70s, against 7.8% for the whole of the 1980s and 90s. The county seat built itself out early and then mostly stopped.

The second number to know is ownership. Only 44.5% of occupied units are owner-occupied, and 24.7% of all units sit in buildings of twenty or more — the converted factories, the apartment blocks and the 189 units built since 2020 around the station. A large apartment building is not our work: no attic, a masonry or curtain-wall envelope, and an owner who is a landlord with a capital plan rather than a homeowner. We say that plainly rather than sending someone out.

What is our work is the rest of Somerville: 42.3% of units in detached houses, 11.9% in two-unit buildings — 679 units — and 7.8% in three- and four-unit buildings, so 19.7% of the borough sits in small two- to four-family houses. Those are Victorian, post-war and mid-century buildings with real attics, real cellars and an owner who can say yes.

The houses we insulate in Somerville

1,438 units predate 1940, and the borough grew around a church, a courthouse and a tavern at a crossroads before the railroad arrived in the 1840s and the mills went up along the Raritan in the 1850s. Main Street and the neighborhoods behind it kept their Victorian buildings. A Victorian house is balloon-framed: the studs run unbroken from the sill to the top plate, so every wall cavity is a chimney carrying cellar air straight to the attic. It has a walk-up garret rather than a crawl-through attic, plaster on lath with no sheathing wrap, and knob-and-tube wiring until proven otherwise. That wiring comes out before anything goes into a wall. The work is fire-blocking the wall cavities at attic and cellar, sealing the stack, chimney and stair chases, insulating the garret floor and dealing with the cellar and rim. Brick built from the local red clay has no cavity, and we do not drill it.

28.6% of the borough is 1940s and 50s: capes, small colonials and early ranches on the streets laid out around the older core. The cape fails at the knee wall — batts on the room side, nothing on the back, and floor joists running out under it to an open eave, so outside air moves under the bedroom floor all winter. The slopes have no baffles, the flat attic above is shallow and the dormer cheeks share the same air path. The 1960s and 70s houses, 27.2% of the stock, are ranches and splits with settled loose-fill, wind-washed eaves, unsealed top plates and a bedroom over a garage.

Then the two- to four-family houses, 19.7% of the borough and the piece that makes Somerville different from its township neighbors. We scope one as a single building, because the stair chase and the floor cavity between apartments run through every unit and sealing half of them does nothing. There is usually one heating plant in the cellar, a low-slope roof over the top unit, an unsealed chase carrying the plumbing and the flue, and balloon framing in the older ones. The order is the stair chase and floor cavities first, then the top plates and chimney at the roof plane, then the cellar and rim, then insulation.

Fuel tells the same story. 66.0% of occupied units heat with utility gas, well below the county, 24.7% heat with electricity and 5.2% with oil. That electric share is mostly apartments with electric resistance heat or heat pumps, and it is why a top-floor apartment owner in a small building feels the attic more than a neighbor with a gas boiler does. On electric heat, the attic plane and the roof over the top unit carry the entire bill.

Peters Brook, the Raritan and the cellar

Somerville is flat ground with the Raritan River along its southern edge and Peters Brook running across it. In September 1999 the borough took a record 13.34 inches of rain in three days from Hurricane Floyd, with serious flooding and considerable damage. Houses that were wet then are the ones we scope differently now.

On a cellar or lower level that has taken water, closed cell foam does not go on the wall. Foam on a wall that floods traps moisture behind it and hides what the water is doing to the sill and joists. On those houses we seal and insulate the first-floor deck and the rim from below, leave the wall able to dry, and keep fiberglass out of the joist bays where it will soak and drop. On a cellar that has stayed dry, closed cell on the band joist and the above-grade portion of the wall is the right assembly, because it stops air and vapor together. In a two-family with the heating plant in the cellar, sealing the cellar also stops the stair chase pulling that air up through both apartments.

We seal before we insulate

Insulation slows heat moving through a surface. It does nothing about air moving through a gap. Lay batts on the garret floor of a balloon-framed Victorian and leave the wall cavities open at the top, and the house will keep drawing cellar air up through the walls and out the roof.

In a Somerville Victorian or two-family the sequence starts at the top and bottom of the wall cavities: block them at the attic plane and at the cellar, seal the stair chase and the floor cavity between units at every level, seal the stack, chimney and plumbing chases, then the top plates. After that the garret floor or the roof cavity over the top unit, then the cellar and the rim. In a post-war cape the order starts at the knee walls instead: block the joist bays under them at the eave line, air barrier on the back side, baffle the slopes, then the flat attic.

If a quote specifies a depth of insulation and never mentions air sealing, it is half a job.

What insulation costs in Somerville

Most of our projects run between $3,500 and $12,500. A two- to four-family is priced as one building, and the drivers are the roof area over the top unit, the number of wall cavities to block and dense-pack, the stair chase and cellar access. A Victorian adds the garret and the wiring question. A post-war cape is usually a smaller scope: knee walls, slopes, flat attic and rim. For the foam side of the price, see what spray foam insulation 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. After air sealing and insulating, homeowners typically save 20% or more on heating and cooling.

Insulation rebates in Somerville

Somerville is PSE&G territory for both electric and gas, so one utility and one program cover the whole borough. That matters here because 24.7% of units heat with electricity: whichever fuel the house burns, the program is the same one.

PSE&G Whole Home Energy Solutions pays up to $7,500 in rebates toward air sealing, insulation and the related envelope work the assessment calls for, plus 0% on-bill repayment of up to $25,000, over 7 years for projects of $10,000 or less and 10 years above that or for income-qualified customers. It is written for owner-occupied homes of one to four units, which is exactly the Somerville building this is about. It starts with an assessment by a BPI-certified contractor participating in PSE&G’s program, and PSE&G does not publish per-measure amounts, so “up to $7,500” is as precise as anyone can plainly be.

PSE&G’s Whole Home Energy Assessment is free for any PSE&G residential gas or electric customer in a home of fewer than five units. PSE&G Home Weatherization installs insulation, air sealing and duct sealing at no cost for households between 250% and 400% of the federal poverty level, in a moderate-income tract, or enrolled in NJ SHARES. New Jersey Comfort Partners does the same at or below 250% of the federal poverty guidelines, $82,500 a year for a family of four, in buildings of 1 to 14 individually metered units — which covers most of the two- to four-family stock here. The 5.2% of Somerville homes on oil are referred to the state instead.

The New Jersey IRA Home Energy Rebates have not launched — the state 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 there is no federal insulation credit on a 2026 job. The full picture is in our New York and New Jersey rebate guide.

Code and climate in Somerville

80.9% of Somerville was built before New Jersey’s first statewide energy subcode of 1 January 1978, the highest pre-1980 share of any town we cover in this county. The Victorian houses off Main Street and the capes behind them were built with no insulation requirement of any kind, and most of what is in their walls and attics was added later by somebody. Somerset County is climate zone 5A, the colder of New Jersey’s two zones.

New Jersey adopted the 2024 IECC on 17 August 2026. For new construction it sets R-49 ceilings — the 2021 edition it replaced called for R-60 — walls at R-30 in the cavity or R-20 plus R-5 continuous, windows at U-0.28 in a 5A county, and air leakage of 3.0 air changes per hour at 50 pascals. A complete permit application filed under the old 2021 code is still accepted until about 16 February 2027. R-49 is the number the state considers right for this climate, and it is what we design to.

A house already standing falls under New Jersey’s Rehabilitation Subcode: insulating an attic does not require bringing the rest of the house to current code and does not require a blower-door test. Blown-in or batt insulation installed against the interior finish is ordinary maintenance with no permit; spray foam and other foam plastic insulation need a permit, which we pull as part of the job.

Common questions about insulation in Somerville

Do you install insulation in Somerville, NJ?

Yes, in the houses: the 42.3% of units in detached houses, the 679 units in two-unit buildings and the three- and four-family houses, plus the Victorians off Main Street. We do not work on the large apartment buildings, 24.7% of the borough, where there is no attic, the envelope is masonry and the decision belongs to the owner of the whole building rather than a resident. If you are not sure which side of that line your building is on, we will tell you on the phone.

How much does insulation cost in Somerville?

Most projects run $3,500 to $12,500. A two- to four-family is priced as one building, and the drivers are the roof area over the top unit, how many wall cavities need blocking and dense-packing, the stair chase and cellar access. A Victorian adds the garret and the knob-and-tube question. A post-war cape is usually smaller: knee walls, slopes, the flat attic and the rim. We give a written scope and a price after a free walk-through.

Are there insulation rebates in Somerville?

Yes. Somerville is PSE&G for gas and electric, so one program covers the house whatever it burns. PSE&G Whole Home Energy Solutions pays up to $7,500 in rebates plus 0% on-bill repayment of up to $25,000, for owner-occupied homes of one to four units, starting with an assessment by a BPI-certified contractor in the program. PSE&G’s separate Whole Home Energy Assessment is free. Comfort Partners does the work at no cost at or below 250% of the federal poverty guidelines. There is no federal 25C credit on a 2026 job.

We own a two-family in Somerville and rent the top floor. Can the whole building be done?

Yes, and it should be. The stair chase, the wall cavities and the floor cavity between the apartments run through both units, so sealing one apartment moves the problem rather than fixing it. We scope the building as one job: cavities blocked at the attic and cellar, chases sealed at every level, the roof or attic over the top unit insulated, then the cellar and rim. PSE&G’s program covers owner-occupied buildings of one to four units, which is what most of these are.

Free energy audit in Somerville

We walk the garret or the roof cavity over the top unit, open a wall cavity at the top and bottom to see whether it is balloon-framed and whether the old wiring is still live, look at the stair chase, the chimney and the plumbing chase, then the cellar, the sill and the rim, and any knee walls if it is a cape. In a house that flooded we spend the time on the cellar and the first-floor deck. You get a written scope and a price, no charge and no obligation.

Call 914-825-6824 or use the contact form. 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.

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