The Home Insulators

Insulation Contractors in New London County, CT

New London’s median home was built in 1947, and 46.7% of its housing predates 1940. Ledyard has 54.5% of its homes from the 1960s and 70s and 68.2% on oil, against 21.3% oil and 41.6% utility gas in the city. For an insulation contractor in New London County, CT, that is the span: city two-families on gas, raised ranches on oil.

Of the county’s 122,712 housing units, 22.3% were built before 1940, 15.7% in the 1940s and 50s, 26.2% in the 1960s and 70s, 21.7% in the 1980s and 90s and 14.1% since 2000; town medians run from 1947 in New London to 1987 in Salem. Detached houses are 64.6% of units and two-unit buildings 7.2%, and 68.1% of occupied homes are owner-occupied. Oil heats 50.8% of them, electricity 21.0%, utility gas 15.0% and bottled gas 8.6%.

Connecticut’s southeastern corner was one of the four counties created in 1666. Norwich sits at the head of the Thames and New London at its mouth, facing Groton; Old Lyme, East Lyme, Waterford and Stonington hold the shore; and Colchester, Lebanon and Griswold fill the higher ground to the north. New London the city is one of the 21 towns, not the county, and the City of Groton lies inside the Town of Groton, whose figures cover both. The twelve town pages carry the detail.

The New London County towns we work in

Nine towns appear only in the county figures for now: Bozrah, Franklin, Lisbon, Lyme, North Stonington, Preston, Salem, Sprague and Voluntown.

  • Colchester — Westchester and the old borough center: median 1984, the youngest of the twelve, with 16.0% propane heat.
  • East Lyme — Niantic’s beach associations and the Flanders orchards: 9.8% built in the 2010s, the most of the twelve.
  • Griswold — Jewett City borough: 19.6% built before 1940, 315 mobile homes, and Jewett City DPU electric in part.
  • Groton — Noank and Groton Long Point: 9.6% townhouses and 32.6% electric heat, the highest shares among the twelve.
  • Lebanon — the county’s high point at Gates Hill, 88.6% detached houses, 14.5% propane heat and no gas company.
  • Ledyard — Gales Ferry and Ledyard Center: 29.4% built in the 1960s, the most of the twelve, and 86.3% owner-occupied.
  • Montville — Uncasville, Oakdale and Chesterfield: 18.5% from the 1940s and 50s, and Bozrah Light & Power in part.
  • New London — the old whaling port, where 19.9% two-unit buildings and 41.6% gas heat top all twelve towns.
  • Norwich — Chelsea, Taftville and Greeneville: 12.2% in three- and four-unit buildings, and the state’s only municipal gas system.
  • Old Lyme — Black Hall, Soundview and Rogers Lake: 88.7% owner-occupied and 90.2% detached, the twelve’s highest on both counts.
  • Stonington — the Borough, Pawcatuck and eastern Mystic: 16.6% of units in two- to four-unit buildings.
  • Waterford — Quaker Hill, Graniteville and Millstone: 23.8% from the 1980s and 90s and 271 mobile homes.

The houses across New London County

Pre-1940 housing is 22.3% of the county and gathers in the old ports: 46.7% of New London, 37.6% of Norwich and 30.0% of Stonington. Whaling wealth built much of New London; two-unit buildings are 19.9% of its units, and three- and four-unit buildings 12.2% of Norwich’s. Many are balloon-framed, with stud bays open cellar to roof, a stair hall rising like a flue and a thin roof cavity over the top unit, so we plan each building as one job, block the bays before dense-packing, and wait for an electrician wherever knob-and-tube may be live.

The village houses are older still: sea captains’ homes on Old Lyme’s Lyme Street, six East Lyme houses from 1699 or earlier, the Trumbull homes on Lebanon’s Green, and Stonington Borough houses reconditioned since the mid-1990s, many as second homes. A timber frame that old may have no wall cavity, so the work is the attic floor, the gaps beside the chimney, the sill and rim, with foam kept out of the walls.

The 1940s and 50s built 15.7% of the county but 25.5% of Old Lyme, with 15.0% in the 1940s alone, and 23.5% of Waterford, which boomed after World War II and built 17.2% of its homes in the 1950s; each is the most of the twelve for its decade. A cape loses heat behind its knee walls, where joist bays under the bedrooms lie open to the eave; a small ranch, across one low attic of flattened fill. With oil heating 66.4% of Old Lyme homes, every closed bay means fewer deliveries.

The 1960s and 70s, the largest era at 26.2%, account for 54.5% of Ledyard, 34.2% of Montville and 31.3% of Groton. In a raised ranch heat escapes along a rim joist sitting out of the ground and up through the garage ceiling into the bedrooms; in a split-level, at the open wall between its two attics. Groton adds townhouses, 9.6% of its units, with party walls open to shared attics, and 32.6% electric heat, where sealing shows on the electric bill.

Colchester has the youngest stock of the twelve, 42.9% of it from the 1980s and 90s, and East Lyme has added 21.1% since 2000. Built with batts in the walls, these houses leak overhead and underneath: cathedral ceilings packed with fiberglass, bonus rooms over garages, recessed lights, ducts in vented attics and bare rims in finished basements.

On the shore, Niantic’s population doubles in the beach season, cottages at Old Lyme’s Point O’ Woods, Hawk’s Nest and Miami Beach rent from late May to mid-October, and Old Lyme counted 1,468 vacant units. A cottage on piers or a vented crawl space takes closed-cell foam and a sealed crawl space if it will be heated, or an insulated floor over dry ground if it will be drained.

Wood heats 14.0% of Lebanon homes, so stovepipe and chimney clearances come first. Mobile homes, 6.8% of Montville’s units, are insulated from underneath, and buildings of twenty or more units, 16.4% of New London’s, go through their owners or boards first.

We seal before we insulate

Insulation slows conducted heat; air leaking through a crack carries heat around it, so fiberglass over an unsealed chimney gap or top plate leaves the draft running.

For a Ledyard raised ranch heated by oil: confirm the boiler’s combustion air, foam the rim and sill, seal the garage ceiling, then the attic’s top plates, wiring holes, plumbing stack, chimney chase and hatch; baffle the eaves, add depth and retest the draft. A New London two-family starts at the wall bays and the top of the stair hall.

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

What insulation costs in New London County

Most of our projects run between $3,500 and $12,500. Price follows the building: a Norwich or New London multi-family is quoted as one job, a raised ranch by the rim and the ceiling over its garage, a cape by its knee walls, a beach cottage by whether it will be heated. Spray foam insulation pays off at rim joists, under cottage floors and in shallow rafter bays; the spray foam cost guide shows why.

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 New London County

Eversource is the only electric company named for Colchester, East Lyme, Ledyard, Lyme, New London, North Stonington, Old Lyme, Preston, Sprague, Stonington, Voluntown and Waterford. Four municipal utilities hold the rest: Norwich Public Utilities (NPU) in Norwich, though Eversource’s list also names Norwich; Groton Utilities in Groton, shared with Eversource; Bozrah Light & Power, a Groton Utilities subsidiary, in Bozrah and parts of Franklin, Lebanon, Montville and Salem; and the Jewett City Department of Public Utilities in parts of Griswold and Lisbon. In Groton and the towns served in part, Eversource has the rest; the electric bill settles it.

For gas, Eversource is listed in Colchester, East Lyme, Franklin, Griswold, Groton, Ledyard, Lisbon, Montville, New London, North Stonington, Salem, Sprague, Stonington and Waterford, though its own gas list leaves out Salem. NPU supplies Norwich and serves parts of Preston and a small section of Bozrah, both shared with Eversource. Lebanon, Lyme, Old Lyme and Voluntown have no gas company.

Municipal utility customers use their own utility’s programs, so a Norwich home on NPU electric and gas is outside Energize Connecticut. NPU’s free Home Energy Savings visit for one- to four-unit homes includes a blower door test to find and correct air leakage and a duct test. Its FY 27 rebate pays up to $1.75 per square foot for attic insulation and $1.25 for wall insulation, to a lifetime maximum of $8,000, for retrofits by a licensed insulation contractor installed from 1 July 2026 through 30 June 2027; attics must finish at R-38 and walls at R-13 or R-21 depending on framing, with pre-approval above $5,000.

Groton Utilities and Bozrah Light & Power give every residential electric customer a free Home Energy Savings assessment, including air sealing and duct testing. Their attic insulation rebate pays up to $2.00 per square foot for R-38 or $2.50 for R-49 if the home has electric heat and/or central air conditioning, up to $5,000 for a single-family home and $2,000 for a condominium or apartment, after the inspection, by a licensed contractor; no program dates are published. Jewett City DPU offers an attic insulation rebate; ask the utility for the current terms. A municipal-electric customer with an Eversource gas account should ask Eversource whether Energize Connecticut applies too.

Home Energy Solutions is open to customers of Eversource, United Illuminating, Connecticut Natural Gas and Southern Connecticut Gas, whatever fuel heats the house, for homes of up to four units not served in six years. The visit costs a $40 copay, effective 1 April 2026, and brings an authorized Home Energy Solutions contractor for health and safety tests, a blower-door test to pinpoint drafts and air leaks, a duct test where there is forced hot air or central air, and up to seven hours of air sealing at no cost, then $10 an hour. Expect a possible waiting list.

The 2026 Energize CT insulation rebate pays up to $2.00 per square foot or 75 percent of the total cost, whichever is less, up to a maximum of $10,000, on attic floors, floored-over attics, walls, basement and garage ceilings and rim joists. Foam under a roof deck is not on that list, so ask the program first. The program requires, in order, a recommendation at a Home Energy Solutions visit, approval before installation, and installation by an approved contractor from the Energize CT Insulation Installers Network.

For one person on Energize CT’s 2026–2027 figures, $48,714 or less is Income Eligible, with up to 100 percent coverage of insulation costs; $48,715 to $64,953 is Enhanced Incentives: a no-cost visit and up to $2.50 per square foot, with zip code setting the actual range. Every address in Griswold, Groton, Lisbon, Montville, New London, North Stonington, Norwich, Preston, Sprague and Voluntown is in a state-designated environmental justice community, which can raise the Energize CT insulation incentive to $2.50 per square foot, up to $15,000. In Bozrah, East Lyme, Lebanon, Ledyard, Stonington and Waterford only parts are designated, and the state’s map shows whether a specific address qualifies.

The Energize CT rebate is paid only on work by the program’s network installers, so ask any installer who quotes, including us, whether they are in that network, and compare prices after any rebate. The Connecticut Green Bank’s Smart-E Loan finances up to $50,000, nothing down, for owner-occupied homes of one to four units, at 6.99% APR over 5, 7 or 10 years, 7.49% over 12 and 7.99% over 15 where offered; only participating contractors can arrange it, so ask yours. Section 25C covers nothing placed in service after 31 December 2025, so insulation installed in 2026 has no federal tax credit. More in our Connecticut rebate guide.

Code and climate in New London County

Housing built before 1980 is 64.2% of the county, from 84.9% of New London to 39.6% of Colchester, and the whole county lies in climate zone 5A.

For new homes and additions, an application filed since 1 October 2022 is governed by the 2022 Connecticut State Building Code, the 2021 IECC with state amendments: R-60 ceilings, or R-49 where its full uncompressed height extends over the wall top plate at the eaves; wood-frame walls of R-30 cavity, R-20 plus R-5 continuous, R-13 plus R-10 continuous or R-20 continuous; R-30 floors; basement walls of R-15 continuous, R-19 cavity or R-13 cavity plus R-5 continuous; and U-0.30 windows. New Connecticut homes must pass a blower-door test, 3.0 air changes per hour at 50 pascals on the prescriptive path and never worse than 5.0. Connecticut’s next code, based on the 2024 IECC, has been adopted in draft, but its effective date has been delayed.

Common questions about insulation in New London County

Do you install insulation in New London County, CT?

Yes, in all 21 towns: two- and three-families in New London and Norwich; capes and small ranches in Waterford and Old Lyme; raised ranches and splits in Ledyard, Montville and Groton; 1980s and 90s colonials in Colchester, Griswold and Lebanon; beach houses in Niantic and Old Lyme; and the smaller towns from Lyme to Voluntown. For apartment buildings and condominium associations, the owner or board decides first.

How much does insulation cost in New London County?

Most projects run $3,500 to $12,500. A New London or Norwich two-family is priced as one building, roof to cellar; a Ledyard raised ranch on its rim, garage ceiling and attic; a Waterford cape on its knee walls; a Colchester colonial on its bonus room; a Niantic cottage on its floor and whether it will be heated. The walk-through and quote cost nothing.

Are there insulation rebates in New London County?

Yes. An Eversource customer pays a $40 copay for a standard Home Energy Solutions visit, and insulation that visit recommends can earn up to $2.00 per square foot or 75 percent of cost, whichever is less, to $10,000, once the program approves it and a contractor from the Energize CT Insulation Installers Network installs it. Norwich Public Utilities pays up to $1.75 per square foot for attics; Groton Utilities and Bozrah Light & Power pay an attic rebate where a home has electric heat or central air.

Which utility do I have in New London County?

Eversource alone supplies electricity in twelve towns, including New London. Norwich Public Utilities serves Norwich, which Eversource also lists; Groton Utilities and Eversource split Groton; Bozrah Light & Power serves Bozrah and parts of Franklin, Lebanon, Montville and Salem; Jewett City DPU serves parts of Griswold and Lisbon. Gas is Eversource in fourteen towns, Norwich Public Utilities in Norwich, both in Preston and Bozrah, and none in Lebanon, Lyme, Old Lyme or Voluntown.

Free estimate in New London County

Our free estimate is a walk-through we do ourselves; it is not a Home Energy Solutions or municipal Home Energy Savings visit and earns no rebate. In a Norwich or New London two-family we check the roof cavity above the top-floor apartment, the stairwell, the cellar rim and the wiring; in a Ledyard raised ranch, the rim, garage ceiling and boiler air supply; in a Waterford cape, behind the knee walls; in a Niantic cottage, under the floor. The written scope and price carry no obligation.

Call 914-825-6824, 8am to 8pm seven days a week, or use our contact page. Based in New Rochelle, NY, we send our own 100-plus in-house crew and never subcontract.

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Insulation services in New London County, CT