46.7% of New London’s housing was built before 1940, 5,844 of its 12,514 units, and the median unit dates from 1947. Only 6.6% has been built since 2000, and 84.9% of the city predates 1980. For several decades from the early 19th century New London was one of the world’s three busiest whaling ports, and that money paid for much of the architecture still standing.
It is also a city of renters. 40.1% of occupied units are owner-occupied. Detached houses are 32.8% of the stock, 19.9% of units sit in two-unit buildings and 9.9% in buildings of three or four, and the rest is apartment buildings, from the 10.8% of units in buildings of five to nine up to the 9.4% in buildings of fifty or more. In those larger buildings the roof and exterior walls belong to the owner or the association, and in a rented apartment that decision belongs to the landlord. Our New London work is the detached house, the two-family whose owner lives in one of the units, and the landlord who owns a two-, three- or four-family and wants it to hold heat.
Utility gas warms 41.6% of occupied units, electricity 30.6% and fuel oil 21.3%. Whatever the fuel, heat lost through a hollow wall is paid for by whoever holds the account.
The houses we insulate in New London
By era, 46.7% of the city predates 1940, 17.2% is from the 1940s and 50s, 21.0% from the 1960s and 70s, 8.5% from the 1980s and 90s and 6.6% has been built since 2000. The 1950s built 12.4% and the 1960s 11.9%; no decade since has built more than the 1970s’ 9.1%.
John Winthrop, Jr. founded the settlement in 1646, and the town was named New London in 1658. Much of it burned in Benedict Arnold’s raid of 6 September 1781. Its historic sites include the Joshua Hempsted House of 1678, the Shaw-Perkins Mansion of 1758 and the U.S. Custom House of 1833, and its principal communities are Downtown and Ocean Beach.
A New London house from before 1940 is usually a wood-frame single-family or a two- or three-family, and its failures are the old-city set. The walls are balloon-framed, with stud bays running unbroken from the sill to the roof, usually empty and often hidden behind a later layer of siding. The sill sits on stone or brick. Over the top apartment there is often no walkable attic, just a shallow, low-slope roof cavity with a few inches of old fill or nothing. Porch roofs frame into the walls and open the bays to outside air. The wiring is presumed to be knob-and-tube until someone has checked, and live knob-and-tube comes out of service before a wall is filled.
The 2,493 units in two-unit buildings are typically the up-and-down kind: one apartment per floor, a front and back stair shared by both, one cellar and one roof. The 1,237 units in three- and four-unit buildings add a floor or a side-by-side plan. Either way it is one job, not one apartment.
After the war came capes, with knee walls open to the eaves, and ranches, with attic fill settled thin around every ceiling fixture.
Renting, owning and the four-unit line
In a city where 40.1% of occupied homes are owned by the people living in them, the first question on any call is whose building it is. The owner, not the tenant, decides what is done to the walls and the roof. A tenant can start the program side, though: Home Energy Solutions accepts renters who get the landlord’s approval, and in the Income Eligible version the landlord completes a landlord authorization and may be asked to pay some of the cost of deeper measures.
The second question is how many units. Energize Connecticut writes Home Energy Solutions for homes of one to four units and the insulation rebate for homes of up to four, and it points owners of buildings of five or more to its Multifamily Initiative instead. That line runs straight through New London. A detached house, a two-family or a four-family sits on one side of it; the 1,349 units in buildings of five to nine, and everything larger, sit on the other.
The third question is whether the owner lives there. The Smart-E Loan and the Energize CT Micro Loan both require an owner-occupied home of one to four units, so an owner living in one apartment of a two-family can use them and an absentee owner cannot.
We seal before we insulate
Insulation slows heat flowing through a wall or ceiling. It cannot stop air, and in a balloon-framed New London two-family the open wall bays and the stair halls move air from the cellar to the roof the way a flue does.
The sealing that matters most happens at the two ends of each stud bay and around the stairs. At the bottom, the sill and rim are sealed where they rest on the foundation and each open bay is closed off from the cellar. At the top, the roof cavity over the upper apartment is opened and the bay tops and ceiling penetrations sealed before it is filled. Each stair hall is sealed as its own shaft before the walls are dense-packed. Chimneys get sheet metal and fire-rated sealant, never foam.
If a quote specifies a depth of insulation and never mentions air sealing, it is half a job.
What insulation costs in New London
Most of our projects run between $3,500 and $12,500. A New London two- or three-family is priced as one building, and the price turns on the stories of hollow wall, whether the walls are reached from outside through the siding or from inside, how the roof cavity over the top apartment can be opened, and how much old wiring has to be retired first. A post-war cape or ranch is mostly knee walls, attic and rim. Spray foam costs are covered separately.
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
New London buys its electricity from Eversource, which is also its gas company. Home Energy Solutions is open to customers of Eversource, United Illuminating, Connecticut Natural Gas and Southern Connecticut Gas, whatever fuel heats the home, for homes of one to four units that have not had the program’s services within six years.
The visit has cost a $40 copay since 1 April 2026, and an authorized Home Energy Solutions contractor carries it out: health and safety tests, a blower-door test, a duct test in a home with forced hot air or central air, and up to seven hours of air sealing at no cost, then $10 an hour. A two- to four-unit property always takes two visits, the second for air sealing and approved upgrades. The program is subject to available funding, so there may be a waiting list.
The 2026 Energize CT insulation rebate pays the lesser of $2.00 per square foot or 75% of the total cost, to a $10,000 maximum, on attic floors, floored-over attics, walls, basement and garage ceilings and rim joists. A hollow balloon-framed wall fits its wall rule: existing insulation of R-4 or less, finished at R-13 or more. Every address in New London 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. The steps come in order: the Home Energy Solutions visit recommends the insulation, the program approves the project before installation, and an approved contractor from the Energize CT Insulation Installers Network installs it. Foam sprayed under a roof deck is not a listed area, so check with the program before planning on money for it.
For a one-person household, Energize CT’s 2026–2027 figures put Income Eligible at $48,714 or less, with no-cost service and up to 100% of insulation costs covered, and Enhanced Incentives at $48,715 to $64,953, with a no-cost visit and up to $2.50 per square foot, though zip code sets that band; above it is the standard tier. The state’s Weatherization Assistance Program, applied for through the energy assistance intake, also serves households at 60% of state median income, with measures that may include air sealing and attic and sidewall insulation.
For owner-occupants, Energize CT’s Micro Loan from Capital for Change lends Eversource customers up to $3,000 interest-free, repaid over 36 months, subject to credit approval, for improvements recommended through Home Energy Solutions and installed by an approved contractor. The Connecticut Green Bank’s Smart-E Loan lends up to $50,000 with no money down at 6.99% APR for 5, 7 or 10 years, 7.49% for 12 and 7.99% for 15 where offered, and is arranged by participating contractors, so ask whether yours is one.
The rebate goes only to work by the program’s network installers, so ask any installer, including us, whether it belongs to the Insulation Installers Network, and compare what each job costs after any rebate. A 2026 insulation job carries no federal tax credit: Section 25C ended for anything placed in service after 31 December 2025. Our Connecticut rebate guide covers the rest.
Code and climate in New London
84.9% of New London’s housing was built before 1980. The water softens winter here, and mid-winter lows on the coast and well inland can differ by as much as 15°F, but the code draws no line at the shore: New London, like all of Connecticut, is in climate zone 5A.
A new home or addition filed since 1 October 2022 comes under the 2022 Connecticut State Building Code, which adopts the 2021 International Energy Conservation Code with Connecticut amendments. That means R-60 ceilings, or R-49 where it stays full height and uncompressed over the top plate at the eaves; wood-frame walls of R-30 cavity, R-20 cavity plus R-5 continuous, or R-13 cavity plus R-10 continuous; R-30 floors; basement walls of R-15 continuous, R-19 cavity, or R-13 cavity plus R-5 continuous; U-0.30 windows; and a new-home blower-door result of 3.0 air changes per hour at 50 pascals on the prescriptive path, never above 5.0. Connecticut has adopted a 2024 IECC-based code in draft, with its effective date delayed.
For existing walls and attics, the rebate’s targets are the useful ones: R-13 in a wall, R-49 on an attic floor.
Common questions about insulation in New London
Do you install insulation in New London, CT?
Yes: detached houses of every era, the 2,493 units in two-unit buildings, and three- and four-unit buildings, whether the owner lives in one apartment or elsewhere. Whatever the building, it is the owner, not a tenant, who decides what is done to the roof and the exterior walls. One phone call settles what a particular building needs.
How much does insulation cost in New London?
Most projects run $3,500 to $12,500. A two- or three-family is priced once for the whole building, on the stories of hollow wall to dense-pack, whether the walls are reached from outside or inside, the roof cavity over the top apartment and any knob-and-tube to retire first. A post-war cape or ranch is usually a smaller scope. Seeing the building costs nothing, and the owner gets the scope and price on paper.
Are there insulation rebates in New London?
Yes. Eversource provides New London’s electricity and gas, so homes of one to four units can use Energize Connecticut’s Home Energy Solutions visit, $40 or free for income-qualified households, with the landlord’s approval for renters. Recommended, pre-approved insulation installed by a network installer can earn up to $2.00 per square foot or 75% of cost, and up to $2.50 and $15,000 because every address in the city is in an environmental justice community. No federal tax credit applies in 2026.
We own a New London two-family and live in one apartment. Which programs can we use?
The main ones are open to you. A two-unit building falls within Home Energy Solutions and the insulation rebate, which cover homes of up to four units, though a two- to four-unit property takes two visits. Because you live there, the building is owner-occupied, which the Smart-E Loan and the Micro Loan both require. Scope the whole building rather than your own floor, since the stairs and wall bays are shared, and if the rebate matters, keep the program’s order: visit, approval, then a network installer.
Free estimate in New London
Our free estimate in New London begins with two questions on the phone: who owns the building, and does the owner live there. On site we look at the porch roofs where they meet the walls, the sill in the cellar, whether the roof cavity over the upper apartment can be reached, any second layer of siding, and the wiring. The owner gets the scope and price in writing. It is not a Home Energy Solutions visit and does not qualify a building for the rebate.
Call 914-825-6824 from 8am to 8pm, any day of the week, or use the contact form. Our base is New Rochelle, NY, and every job is done by our own 100-plus in-house crew, never a subcontractor.
Learn more
- Insulation contractors across New London County
- Insulation contractors in Waterford
- Insulation contractors in Groton
- Insulation contractors in Norwich
- Insulating older homes
- Wall insulation
- Basement ceiling insulation