Yonkers has 85,006 housing units, more than anywhere else in Westchester
County, only a quarter of them detached. Nearly one in five sits in a two-,
three- or four-family building.
That is a different job from a suburban colonial, and the one nobody writes
about plainly. So this page is for the owner of a Yonkers two-family first.
The houses we insulate in Yonkers
The median Yonkers home was built in 1958. About 26.6% of the stock predates
1940 and another 45.9% went up in the three decades after — 18.4% in the
1950s, 15.6% in the 1960s, 11.9% in the 1970s. Detached houses are 24.7% of
the total and 46.2% of units are owner-occupied. 7,789 units are in two-family
houses and 8,913 in three- and four-family buildings: 19.7% of the city, and
by volume the biggest retrofit opportunity in the county.
In the pre-1930 frame two- and three-families the defining finding is balloon
framing: stud bays running uninterrupted from the sill plate to the attic, so
every exterior wall works as a flue the full height of the building. The floor
assemblies between units are just as open. Sealing those is not only a heat
measure — an open cavity between two dwelling units carries smoke, fire
and combustion gases, so the blocking that stops the stack effect also
restores compartmentation.
Below the first floor the cellar ceiling over an unconditioned basement is
almost always bare, with the boiler and hot water tank heating a space nobody
occupies and the rim joist leaking all winter. Where there is a tuck-under
garage, the joist bays over it run open into the floor above. Over the top
unit, a flat roof is a 6 to 10 inch joist cavity with no soffit-to-ridge path,
so it cannot be vented: dense-pack it, or rigid board above the deck at the
next re-roofing, never vented batts. In the pre-1940 stock we check for
knob-and-tube first, because it has to come out before anything goes into a
wall.
If your Yonkers house went up in the 1960s or 70s, you are adding, not fixing
More than a quarter of Yonkers went up between 1960 and 1979, and those houses
are insulated. That is the problem. R-11 to R-13 walls and an R-19 attic were
normal for the day, so the owner sees insulation and assumes the envelope is
handled.
Nothing is broken. The standard moved. Bringing an R-19 attic to a modern
retrofit depth is the cheapest work in this stock, and it comes with a punch
list: recessed lights, bath fan penetrations and a dropped kitchen soffit,
none of them built for contact with insulation. Seal or replace the old cans,
vent the fan outside rather than into the attic, cap the soffit with a rigid
air barrier, and the added depth performs.
We seal before we insulate
Insulation slows heat moving through a surface. It does nothing about air
moving through a gap. Pack a leaky attic with cellulose and you have a leaky
attic with cellulose in it — the air still moves, it just moves through
something fluffier.
In a Yonkers multifamily the sealing sequence is the job. Block the stud bays
at the plates, close the floor cavities between units, seal the stairwell
chase at each floor, close the top plates and the framing around the plumbing
stack and the chimney, then insulate. In that order the cavities hold what you
put in them and the building is compartmented.
If a quote specifies a depth of insulation and never mentions air sealing, it
is half a job.
What insulation costs in Yonkers
Most of our projects run between $3,500 and $12,500. A
two-family is priced as one building, not two apartments, because the stud
bays, floor cavities and roof plane are shared. What moves the number is the
count of wall bays to block and dense-pack, the top-floor ceiling or flat-roof
area, and access to the cellar and rim.
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 Yonkers
Yonkers is Con Edison territory for gas and electric, and the
first thing to know is what is closed. Con Edison’s residential
Weather Ready weatherization program is not accepting
applications, and its own page tells Westchester customers to expect
news about 2027 incentives and to use NYSERDA meanwhile. A “$4,000 from Con
Edison” figure still shown on one of their index pages is stale.
The live program is NYSERDA Comfort Home:
$2,500 to air seal and insulate the attic and rim joist,
$3,000 if wall and floor insulation goes in too, and
$2,000 more toward ENERGY STAR windows afterwards. The
contractor must be on NYSERDA’s Comfort Home list.
In a city where fewer than half of households own their home,
EmPower+ matters more. Households at or below 80% of
area median income get the work at no cost up to
$14,000 downstate; moderate incomes pay half the cost up to
$7,000. It is how New York delivers federal HEAR money, and here it
is often the difference between a quote and a job. See
the full New York rebate guide.
The federal Section 25C tax credit ended for anything placed in service after
31 December 2025. There is no federal insulation credit on a
2026 job.
Code and climate in Yonkers
Roughly seven in ten Yonkers units went up before 1980. Westchester is
climate zone 4A, and the rulebook is the 2025 Energy
Conservation Construction Code of New York State, in force since
31 December 2025 and based on the 2024 IECC.
For new construction and additions it sets R-49 ceilings,
R-30 wood-framed walls (R-20 cavity plus R-5 continuous is
the usual alternative), R-30 floors, and R-15 continuous or R-19 cavity in
basement walls. Those numbers changed at the end of 2025, so anyone quoting
R-60 as New York code is reading Connecticut’s. None of it applies to
a building already standing. The code expressly does not require an
existing building to be altered; it only requires that altering an assembly
not leave less insulation than was there before. The Department of Energy
separately recommends R-60 for a retrofit attic in this zone, which is
guidance, not law.
Common questions about insulation in Yonkers
Do you install insulation in Yonkers, NY?
Yes, and most of what we do here is two-, three- and four-family buildings,
19.7% of the city’s housing. We scope a multifamily as one building rather
than unit by unit, because the stud bays, floor cavities and roof plane are
shared and sealing half of them does not work.
How much does insulation cost in Yonkers?
Most projects run $3,500 to $12,500 for the building. The drivers are the
number of wall bays to block before dense-packing, the top-floor ceiling or
flat roof area, and how reachable the cellar and rim are around the boiler.
Knob-and-tube removal, where it is needed, is an electrician’s cost ahead of
ours.
Are there insulation rebates in Yonkers?
Yonkers is Con Edison territory, and Con Edison’s Weather Ready program is not
accepting applications. The live money is NYSERDA Comfort Home — $2,500
for air sealing plus attic and rim joist, $3,000 with walls and floors —
and EmPower+, at no cost up to $14,000 downstate for households at or below
80% of area median income.
We own a Yonkers two-family and live in one unit. Should we do the whole building?
Usually yes, and often you have no choice. The stud bays and floor cavities
run between the units, so sealing only your apartment leaves the leak path
intact and the stack effect still pulls air up the building. The blocking
between floors also restores fire and combustion-gas separation, which is
worth having whoever pays the heat.
Free energy audit in Yonkers
We walk the cellar, the stairwell, the top-floor ceiling and any attic, then
give you a written scope and a price. No charge, no obligation. If the attic
is fine and the real work is the cellar ceiling and the floor cavities, we
will tell you that.
Call 914-825-6824 or use the form on this page. 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.