Walls are the last surface in a Union County house to get dealt with, and usually the one with nothing in it. 79.5% of the county’s 211,269 units were built before New Jersey’s first statewide energy subcode of 1 January 1978, and the sequence in those houses has been the same for decades: the attic gets insulation, the windows get replaced, and the walls stay exactly as the builder left them. Wall insulation is the step that finishes the envelope, and in a county where 105,038 units are detached houses it is available to a lot of people who assume it is not.
Two facts about the local stock decide how it is done. 24.1% of the county predates 1940, which usually means balloon framing, plaster on lath and stud bays that run without a break from the cellar to the attic floor. Another 34.8% came out of the 1940s and 50s, which means two-by-four walls behind wood, aluminum or vinyl siding, empty or holding a thin batt that has slumped. The first group needs blocking before anything can be blown; the second is often the simple drill-and-fill this trade was built on.
Where wall insulation pays in Union County houses
Balloon-framed houses in the older towns. Pre-1940 stock runs to 36.0% in Westfield, 33.4% in Summit, 30.8% in Cranford, 27.5% in Elizabeth and 20.7% in Linden. In those walls the stud bay works as a flue, drawing from the cellar and letting go at the attic floor, and until it is blocked at both ends there is nothing to fill. Blocking first, then dense-pack, is the order, and it is also why these houses often gain more from the wall work than a newer one does.
Post-war tract houses with empty two-by-four walls. The 1940s and 50s account for 41.7% of Union Township, 40.7% of Scotch Plains and 41.0% of Clark, with Kenilworth in the same belt. These are the best candidates in the county: regular framing, a known stud spacing, and siding that can take a course off and go back. Where a house is due for new siding anyway, the same trip can add board on the outside of the sheathing, which is the one chance an existing wall gets at continuous insulation.
Knee walls in capes and finished attics. Every cape in the county has two of them, short walls between a bedroom and an unheated side attic, and they are walls in every sense the code recognizes: the 2024 IECC treats a knee wall as a wood-framed wall and wants an air barrier between the room and the attic. Batts stapled between those studs with open attic air behind them do very little, which is why attic knee wall work is wall work, not attic work.
The wall and ceiling shared with a garage. Clark drew 38.3% of its houses from the 1960s and 70s, New Providence 32.0% and Berkeley Heights 34.7%, and that era is full of bedrooms sitting over an attached garage. Closed cell foam at R-6.9 to R-7.1 per inch is the usual answer on the garage side, because it is a shallow assembly and it stops the air as well as the heat. New Jersey requires a one-hour fire-rated floor-ceiling assembly under living space over a garage, so what covers the insulation is part of that scope.
How we do wall insulation in Union County
We look inside the wall before quoting it. An outlet cover comes off, an infrared camera runs the elevation, and we note the framing, the wiring, the siding and any sign of water. Three things stop the job on the spot: live knob-and-tube, which the Department of Energy says should be replaced before insulating and which rules out drill-and-fill where it runs; siding shingles that might be asbestos cement, which the EPA lists among asbestos products and which get tested before anyone drills them; and anything pebble-like that could be vermiculite, left for a licensed professional. None of those three is our trade, and none of them is a reason to guess.
In a closed wall the method is drill-and-fill. Holes of about 1 to 2 inches go into each stud bay, roughly 6 inches below the ceiling, through the plaster or drywall inside or through the sheathing once a strip of siding is off. Each bay is packed to the manufacturer’s density — 3.5 to 4.5 pounds per cubic foot for cellulose, 1.8 to 2.6 for fiberglass — dense enough to resist settling and slow the air down. Bays over headers, under windows and behind cabinets get their own holes, with a second hole below any blocking we find. An infrared scan confirms every bay is full before the holes are plugged and patched, or the siding and its drainage layer go back. At cellulose’s R-3.2 to R-3.8 per inch, a filled two-by-four bay comes to about R-11 to R-13. Injection foam is the other route through the same holes, and where we use it you get the data sheet, R-value per inch and shrinkage included, plus the same scan.
Plaster changes the approach. Drilling from outside can break the plaster keys that hold a ceiling and wall together, and drilling from inside raises dust, damages the finish and can disturb lead paint. In a Summit or Westfield house with original plaster worth keeping, the better route is usually from outside under new siding, or air sealing the house and leaving those bays alone. Lead-safe work, plaster repair and siding are priced by the trades that do them.
When a wall is open, the choice widens. A two-by-four bay takes R-13 or R-15 batts or about R-24 to R-25 of closed cell; a two-by-six takes R-21 or R-23 batts, and an R-19 batt squeezed into a two-by-six delivers R-17 to R-18, so it is not the bargain it looks like. Mineral wool at about R-4 per inch suits a bathroom or bedroom wall where sound matters as much as heat. Open cell foam fills the irregular framing of an older house that batts never fit. Whatever goes in, the corners, headers and doubled studs get sealed, because those leak even in a foamed wall. Wet or rodent-fouled material is removed under containment and vacuumed out with a HEPA insulation vacuum; mold on framing or sheathing goes to a remediation company before we close anything up.
What wall insulation costs in Union County
Most of our projects run between $3,500 and $12,500. Drill-and-fill and injection foam are priced by bay count and access, so the elevations, the height of the house, and whether we work from inside or from behind the siding set the number. A balloon-framed Cranford or Elizabeth house needs blocking before any of that, which is time. An open wall in a renovation is priced by area and material, batts against open or closed cell. Exterior board under new siding is priced by layers and by the openings that have to be flashed. Siding, electrical, drywall, plaster and lead-safe work belong to the trades that perform them. The rest of our pricing is in the insulation cost guide.
Rebates for wall insulation in Union County
Wall work counts as envelope work, so it sits inside the same programs the attic does, and the utility depends on the town. PSE&G supplies electricity to seventeen of the twenty-one municipalities and Elizabethtown Gas the gas to sixteen, Elizabeth, Linden, Union Township, Westfield, Cranford, Scotch Plains, Clark and Kenilworth among them. Berkeley Heights, New Providence, Summit and Springfield take JCP&L electricity with PSE&G gas. Where the gas and the electric come from different companies, either program is open to you; begin with the one that bills your heating fuel and confirm with the other.
The program is Whole Home Energy Solutions, for owner-occupied homes of one to four units, up to $7,500 per project, and every project has to include air sealing along with the insulation the assessment calls for. Elizabethtown Gas and JCP&L publish the formula: $2,000 for a modeled 5% saving plus $200 for each percentage point above it, never more than $7,500 or half the project cost, with 0% on-bill repayment of $2,500 to $25,000. The gas route requires an active account and gas heat. PSE&G publishes no formula, just the same $7,500 ceiling and 0% on-bill repayment of up to $25,000, starting with an assessment by a BPI-certified contractor participating in its program who sets that fee. Ask any installer, including us, whether they participate in the program you choose.
Each utility also offers a free Whole Home Energy Assessment, the lighter walk-through, separate from the priced assessment behind the rebate. At no cost, Home Weatherization for Income-Qualified Customers covers households between 250% and 400% of the federal poverty guidelines with up to $14,000 in upgrades and $2,500 in health and safety repairs, insulation in walls included, and New Jersey Comfort Partners serves households at or below 250%, $82,500 for a family of four in 2026. New Jersey’s IRA Home Energy Rebates remain in development and closed to applications, and the federal 25C credit ended for anything placed in service after 31 December 2025. Current detail is in our New York and New Jersey rebate guide.
Code and climate in Union County
This is a climate zone 4A county. Under the 2024 IECC, adopted in New Jersey on 17 August 2026, a new wood-framed wall needs R-30 in the cavity, or R-20 plus R-5 continuous, with R-13 plus R-10 continuous and R-20 continuous as the other paths, windows at U-0.30 in a 4A county, and 3.0 air changes per hour at 50 pascals for the house as a whole. No two-by-four cavity reaches R-30 by itself, which is why new walls here carry board on the outside and why re-siding is the moment to add it.
The interior vapor retarder condition — faced batts or vapor retarder paint unless the siding or the exterior foam meets the exceptions — is written for the zone 5 counties: Bergen, Hunterdon, Morris, Passaic, Somerset, Sussex and Warren. Existing houses here fall under New Jersey’s Rehabilitation Subcode, where filling a wall does not oblige anyone to bring the house to current code and no blower-door test is required. Blown-in and batt insulation installed against an interior finish is ordinary maintenance with no permit, while foam plastic needs a permit, which we pull as part of the job.
Towns we serve in Union County
We insulate walls throughout the county’s twenty-one municipalities; these eleven have pages of their own.
Common questions about wall insulation in Union County
Can you blow insulation into closed walls in a Union County house?
Yes, that is most of what we do here. Cellulose or fiberglass is dense-packed through 1 to 2 inch holes in each stud bay, from inside through plaster or drywall, or from outside once a course of siding comes off, then the holes are patched or the siding goes back. An infrared scan proves each bay is full. Two conditions stop it: live knob-and-tube wiring, and a balloon-framed wall that has not been blocked at the top and bottom first.
What are the best wall insulation types for these houses?
For a closed wall, dense-pack cellulose at R-3.2 to R-3.8 per inch, which brings a two-by-four bay to about R-11 to R-13, or injection foam through the same holes. For an open wall, R-13 or R-15 batts in a two-by-four, R-21 or R-23 in a two-by-six, mineral wool where sound matters, or spray foam where the framing is irregular. For the wall shared with a garage, closed cell. Skip an R-19 batt in a two-by-six; compressed, it gives R-17 to R-18.
How much does wall insulation cost in Union County?
Most projects run $3,500 to $12,500. Bay count and access drive it: a one-story ranch in Clark with vinyl siding is quicker than a two-and-a-half-story Westfield house with original plaster and cedar shingles. Blocking a balloon-framed wall adds time before anything is blown. Exterior board under new siding is priced by layers and openings. Siding, electrical, drywall and lead-safe work come from the trades that do them and are quoted separately.
Do you insulate attic knee walls and garage walls in Union County?
Both, and they are common here. A cape’s knee wall needs a real air barrier on the attic side, not a batt facing open air, and the joist bays running under the bedroom floor get blocked at the same time. A garage wall or the ceiling below a bedroom over a garage usually takes closed cell for the R-value in a shallow assembly, and in New Jersey that ceiling is a one-hour fire-rated assembly, so the covering is part of the job.
Free energy audit in Union County
We take an outlet cover off, scan the elevations with an infrared camera and read what the walls actually hold: empty bays, slumped batts, blocking, balloon framing, old wiring, and where water has been. Outside we look at the siding and whether it can come off and go back. Then you get a written scope that names the method, the product and its density, how the holes are patched, what an infrared scan will confirm, which other trade has to go first, and the price.
Call 914-554-2289, 8am–8pm, seven days. The Home Insulators is family-owned, works out of New Rochelle, NY, and sends its own 100-plus-person in-house crew; we never subcontract.
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