The 1970s built 17.7% of Groton’s housing, more than any other decade, and the median unit dates from 1973. Together the 1960s and 70s account for 31.3% of the town’s 18,285 units and the 1980s and 90s another 24.6%, so most of what we insulate here went up after the war: raised ranches, splits, colonials and townhouses. Only 15.1% predates 1940.
Heat is the second story. Fuel oil warms 47.7% of occupied units and electricity 32.6%, with utility gas at 10.7% and bottled gas at 6.4%. That electric share matters twice in Groton, because Groton Utilities, the municipal utility serving the City and Town of Groton, writes its attic rebate for homes with electric heat or central air conditioning.
Groton is also the home of the Naval Submarine Base New London and of Electric Boat, whose plant on the Thames employs 10,500 people, and only 51.9% of its occupied units are owner-occupied. The apartment buildings, from the 7.4% of units in buildings of five to nine to the 5.5% in buildings of fifty or more, are run as whole properties, where the roof and the exterior walls belong to the owner or the association. In the 8,818 detached houses, 48.2% of the stock, one owner decides; in the 1,747 attached single-family homes that depends on whether an association holds the outside of the building.
The houses we insulate in Groton
By decade, Groton built 11.8% of today’s housing in the 1950s, 13.6% in the 1960s, 17.7% in the 1970s, 13.6% in the 1980s and 11.0% in the 1990s. The 1940s built only 4.4%.
The oldest houses belong to the places that grew with the ships. Groton separated from New London in 1705 and became a shipbuilding town: after the Revolution the yards on the Mystic River were the busiest, by 1846 Groton was one of the world’s prime whaling ports, and after 1870 shipbuilding moved to Noank. When iron ships drew workers during World War I, housing ran short and Groton Realty hurried to build hotels and cottages. Groton Bank, also called Groton Heights, and Burnett’s Corner are historic districts. A house from before 1940 usually has empty walls and an open rim, and we treat its wiring as knob-and-tube until we have seen it; live knob-and-tube is retired before a wall is filled.
The 1960s and 70s built Groton’s raised ranches and splits. A raised ranch leaks at its long rim joist, half above grade, and at the bedroom or family room set over the garage, where the floor framing is open to garage air. A split adds the joint between levels, where the upper floor’s framing opens into the attic over the lower wing. Both have a low attic with loose-fill or batts that have settled and gaps at every light box and plumbing vent. The contemporaries of the same years add cathedral ceilings with batts packed tight to the roof deck and no room for air.
The 1980s and 90s added colonials and townhouses. The colonial’s walls hold insulation already; its attic leaks at the hatch, the top plates and the recessed lights. A townhouse’s weak point is the party wall where it runs up into a shared attic. In a condominium the association, not the individual unit owner, usually controls the roof and the exterior walls.
Fuel decides how fast any of it pays back. On oil, the saving is fewer deliveries. On electric baseboard, every leak is billed by the kilowatt-hour.
Groton Utilities, Eversource and the electric-heat question
Two questions settle the rebate route in Groton. The first is whose name is on the electric bill. Groton Utilities serves the City and the Town of Groton, and Eversource’s own list of electric towns also names Groton without saying which streets; the bill settles it. Gas in Groton comes from Eversource.
The second question applies to Groton Utilities customers: how is the house heated and cooled? Its free Home Energy Savings assessment is open to every residential electric customer. Its attic insulation rebate, as the utility publishes it, is for homes with electric heat, central air conditioning or both. A raised ranch on electric baseboard fits that description; an oil-heated cape with window air conditioners does not.
We seal before we insulate
Insulation resists heat passing through it. It does not stop air moving around it: warm air escapes at the top of the house and cold air is drawn in at the bottom to replace it.
In a Groton raised ranch we start low. Seal and insulate the rim joist all the way around the lower level; seal the garage ceiling where it meets the house, and insulate the floor over the garage from below; then go up and seal the top plates, the light boxes, the plumbing vents, the bath fan housing and the hatch. Baffles go in at the eaves so the vents stay clear. Only then does the attic floor get its new depth.
If a quote specifies a depth of insulation and never mentions air sealing, it is half a job.
What insulation costs in Groton
Most of our projects run between $3,500 and $12,500. In a Groton raised ranch the number follows the attic area, the length of rim joist and the size of the room over the garage; in a 1970s contemporary, whether the cathedral ceilings are opened and filled. A townhouse is mostly party wall and attic plane. Empty pre-1940 walls add dense-packing. Spray foam costs are laid out 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 Groton
Groton’s electric service is split between Groton Utilities, a municipal utility, and Eversource, and its gas company is Eversource. The electric bill tells you which paragraphs below apply.
Groton Utilities customers. The utility’s Home Energy Savings Program is a free comprehensive in-home energy assessment for all its residential electric customers, covering air sealing, duct testing and sealing, water-saving and LED measures, and incentives for insulation upgrades. Its attic insulation rebate pays up to $2.00 per square foot for R-38 or $2.50 per square foot 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. The Home Energy Savings inspection must come before installation, a licensed contractor must do the work, the rebate is one per account, and the account must be paid in full. No program dates are published, so confirm current terms with the utility. These are Groton Utilities’ figures, not Energize Connecticut’s. A Groton Utilities customer with an Eversource gas account should ask Eversource whether the house also qualifies for Energize Connecticut.
Eversource customers. 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 one to four units that have not had the program’s services within six years. The visit costs a $40 copay as of 1 April 2026. The program’s authorized contractor checks health and safety, runs a blower door to find the leaks, tests ducts in a house with forced hot air or central air, and air-seals free for up to seven hours, at $10 an hour after that. Expect a possible wait.
Energize CT’s 2026 insulation rebate is the lesser of $2.00 per square foot or 75% of the total cost, capped at $10,000, on attic floors, floored-over attics, walls, basement and garage ceilings and rim joists. Every address in Groton 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. To collect it, a household needs the insulation recommended at the Home Energy Solutions visit, the project approved before work starts, and an approved contractor from the Energize CT Insulation Installers Network doing the installation. Roof-deck foam is not among the listed areas; ask the program first. Income tiers, using Energize CT’s 2026–2027 numbers for two people: Income Eligible at $63,703 or less, with no-cost service and up to 100% of insulation costs covered; Enhanced Incentives from $63,704 to $84,939, where the visit is free and insulation earns up to $2.50 per square foot, though zip code sets the true band; the standard tier above that.
Because the Energize CT rebate pays only on network installers’ jobs, ask any installer who quotes, including us, whether they are in that network, and compare prices after any rebate before you choose. Whatever the utility, the Connecticut Green Bank’s Smart-E Loan lends up to $50,000, no money down, on owner-occupied homes of one to four units: 6.99% APR for 5, 7 or 10 years, 7.49% for 12, 7.99% for 15 if the lender offers it. Its participating contractors arrange it, so ask the contractor. The federal Section 25C credit is over for anything placed in service after 31 December 2025, and a 2026 insulation job earns no federal tax credit. The statewide programs are set out in our Connecticut rebate guide.
Code and climate in Groton
62.6% of Groton’s housing was built before 1980. Groton sits in climate zone 5A, like every Connecticut town.
A house or addition filed for since 1 October 2022 is built to the 2022 Connecticut State Building Code, whose energy rules are the 2021 International Energy Conservation Code as the state amended them. The ceiling target is R-60, satisfied by R-49 when that R-49 runs uncompressed over the top plate at the eaves. Floors take R-30 and windows U-0.30. A wood-frame wall needs R-30 in the cavity, or R-20 with R-5 of continuous insulation, or R-13 with R-10 continuous; a basement wall needs R-15 continuous, R-19 in the cavity, or R-13 with R-5 continuous. Blower-door testing on a new home must show 3.0 air changes per hour at 50 pascals on the prescriptive path, and 5.0 is the limit on any path. The state has a 2024 IECC-based successor in draft whose effective date has been delayed.
For an existing attic the rebate programs set the practical targets: Groton Utilities pays more at R-49 than at R-38, and Energize CT asks for R-49 or more.
Common questions about insulation in Groton
Do you install insulation in Groton, CT?
Yes. Most of our Groton work is the raised ranches, splits and contemporaries of the 1960s and 70s, 31.3% of the town, and the colonials and townhouses of the 1980s and 90s, plus older houses in the villages, from Groton Bank to Noank and Mystic.
How much does insulation cost in Groton?
Most projects run $3,500 to $12,500. A raised ranch is priced on its attic area, the rim joist around the lower level and the floor over the garage. A 1970s contemporary adds its cathedral ceilings, and a townhouse is mostly party wall and attic. An older village house with empty walls adds dense-packing. We walk the house at no charge and give you the scope and the price in writing.
Are there insulation rebates in Groton?
Yes, and the electric bill decides which. Groton Utilities customers get a free Home Energy Savings assessment, and homes with electric heat or central air can get up to $2.50 per square foot for an R-49 attic. A home billed by Eversource is in Energize Connecticut: a $40 Home Energy Solutions visit and up to $2.00 per square foot or 75% of cost, which can reach $2.50 and $15,000 because all of Groton is an environmental justice community. No federal tax credit applies in 2026.
Our Groton house is on Groton Utilities, heats with oil and has no central air. Is there an attic rebate?
Not under Groton Utilities’ attic rebate as it is published, which is for homes with electric heat and/or central air conditioning. The utility’s free Home Energy Savings assessment is still open to you as a residential electric customer, and it is worth booking. If the house also has an Eversource gas account, ask Eversource whether it qualifies for Energize Connecticut. Otherwise the work stands on its own payback, which on oil is counted in deliveries, and a Smart-E Loan can spread the cost.
Free estimate in Groton
In a Groton raised ranch our free estimate starts at the lower level, with the rim joist and the ceiling of the garage, then goes up to the attic for the top plates, the old fill and the eaves. In a contemporary we check the cathedral ceilings; in a village house, the walls and wiring. We ask how the house is heated and whose name is on the electric bill, then give you a written scope and a price. It is not Groton Utilities’ Home Energy Savings assessment or Energize CT’s Home Energy Solutions visit, and it does not qualify a house for either rebate.
Call 914-825-6824 any day from 8am to 8pm, or use the contact form. We are based in New Rochelle, NY, and our 100-plus in-house crew does the work itself, never through subcontractors.
Learn more
- Insulation contractors across New London County
- Insulation contractors in Ledyard
- Insulation contractors in New London
- Insulation contractors in Stonington
- Attic insulation
- Garage insulation and the room above it
- Air sealing