Glastonbury has 154 houses built before 1800, the second-highest count of genuine colonial houses of any town in the country, and four of them date from the 1600s. The John Hollister House, built around 1675, is one of Connecticut’s five oldest. Yet the median Glastonbury home dates from 1976. Only 7.8% of the town’s 14,551 housing units predate 1940, while 31.1% are from the 1960s and 70s and 29.7% from the 1980s and 90s.
75.5% of units are detached houses and 8.7% attached, and 82.4% of occupied homes are owner-occupied. Fuel oil heats 34.9% of homes, gas 49.8%, electricity 8.5% and bottled gas 5.1%. With that much of the town paying for heat by the delivery, the case for sealing and insulating is often counted in gallons rather than on a gas bill.
The houses we insulate in Glastonbury
By era, 19.0% of Glastonbury is from the 1940s and 50s, 31.1% from the 1960s and 70s, 29.7% from the 1980s and 90s, and 12.4% has been built since 2000; the 1970s and the 1980s each produced 18.9% of the stock, 2,751 units apiece, and 57.9% was built before 1980. The town runs from the banks of the Connecticut River up into foothills, and its communities include Glastonbury Center, South Glastonbury, East Glastonbury, Addison, Buckingham and Hopewell.
The 1950s and 60s, 14.0% and 12.2% of the town, added capes, ranches and early split-levels. They fail where their generation always does: knee walls with no air barrier on the attic side, attics of thin and settled loose-fill, and a basement rim that has never been sealed.
The 1970s through the 90s built much of Glastonbury. Minnechaug Mountain became a major residential area from the 1970s until the late 1990s, built on relatively steep hills, and growing subdivisions of large homes surround Diamond Lake. Houses of those decades have insulated walls, so the losses are elsewhere: an attic of R-19 to R-30 pierced by recessed lights, a hatch and a plumbing chase; cathedral ceilings and skylight wells with batts pressed against the roof deck and no vent space; a bonus room over the garage with open joist bays under its floor; an air handler and ductwork in the attic, outside the insulation; and on a hillside lot, a walk-out lower level whose exposed wall and rim face the weather like an upper floor.
Elevation matters too. The rural parts of Glastonbury, at about 800 feet near Bolton and Hebron, run colder than the town center, and a house up there pays for the same leaks over a harder winter.
154 houses from before 1800
Thirty families settled Pyaug, the land that became Glastonbury, in 1636. In the 18th and early 19th centuries it was a shipbuilding town, with sawmills, charcoal kilns and foundries around the yards. The houses from that time are a different kind of building and need a different kind of insulation job.
A colonial house of the 1700s is usually a timber frame around a central chimney, sheathed in wide boards, without the regular stud cavities of a later house. The spaces in its walls may be irregular, shallow, interrupted by bracing or filled with brick or clay, and a single test hole says little about the bay next to it. The Jonathan Hale House on Main Street, among Connecticut’s oldest surviving brick houses, is a reminder that some early walls are solid masonry with nothing to fill. We do not blow those walls on a guess.
What works in an old house is the part that can be done without changing how the building handles moisture. The garret or attic floor, sealed first at the chimney, the top plates and any old stair opening, then insulated. The cellar, where the sill sits on stone and the rim is open to outdoor air. The later wings and ells, usually stud-framed, which can be treated like a newer house. We are careful with closed cell foam against old plank or masonry walls, which have dried in both directions for two centuries.
We seal before we insulate
Batts and blown insulation resist heat conducted through a ceiling or a wall. They do almost nothing to stop moving air, and in a 1980s Glastonbury colonial the air paths hide in plain sight: every recessed light, the attic hatch, the chase carrying plumbing and flue from basement to attic, and the ductwork running through the attic itself.
In that house the order is: seal the chases and top plates from the attic; cover and seal the recessed lights; weatherstrip and insulate the hatch; seal the duct joints and the air handler cabinet; baffle the eaves and any cathedral slopes; close the joist bays under the bonus room; then bring the attic floor up to depth and seal the rim in the basement.
If a quote specifies a depth of insulation and never mentions air sealing, it is half a job.
What insulation costs in Glastonbury
Most of our projects run between $3,500 and $12,500. In a 1970s to 90s house the number follows the attic area, the recessed lights and cathedral slopes to be dealt with, the bonus room floor and the ductwork in the attic. In a pre-1800 house it follows how much of the garret and cellar can be reached and whether a later wing has open walls. Foam prices are broken down in our spray foam cost guide.
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 Glastonbury
Two companies serve Glastonbury: Eversource for electricity and Connecticut Natural Gas (CNG) for gas. For the 34.9% of homes on oil that matters less than it seems, because Home Energy Solutions is open to customers of Eversource, United Illuminating, Connecticut Natural Gas and Southern Connecticut Gas regardless of heating fuel, and an oil-heated house signs up with its electric account. One- to four-unit homes are eligible if the program has not served them in the past six years.
Everything starts with the Home Energy Solutions assessment, done by an authorized contractor for a $40 copay, the rate since 1 April 2026. The contractor checks health and safety, runs a blower door to locate air leaks, tests the ducts if the house has forced hot air or central air conditioning, and seals leaks for up to seven hours at no charge, billing $10 an hour after that. Funding is limited, and a waiting list is possible.
Insulation recommended at that assessment can earn the 2026 Energize CT insulation rebate: $2.00 per square foot or 75 percent of total cost, whichever is less, with a single $10,000 maximum, on attic floors, floored-over attics, walls, basement and garage ceilings and rim joists. In a 1980s attic the entry rule decides it: the existing floor must hold R-19 or less, and the finished floor must reach R-49, or R-38 where R-49 is not structurally practicable. A floored-over garret at R-4 or less must reach R-19. The program must approve the project before installation, and the installer must be an approved contractor from the Energize CT Insulation Installers Network. A cathedral ceiling foamed from below the roof deck is a different case, because the underside of a roof deck is not a listed area; confirm with the program before relying on a rebate for it. Parts of Glastonbury are designated environmental justice communities; the state’s map shows whether a specific address qualifies, and there the incentive can reach $2.50 per square foot, up to $15,000.
A household of four lands in one of three tiers on Energize CT’s 2026–2027 figures. At $124,909 or more it is the standard tier. Between $93,682 and $124,908, above the state’s 60 percent income median but under 80 percent of area median income, it is Enhanced Incentives, with a no-cost assessment and up to $2.50 per square foot, the band adjusted by zip code. At $93,681 or less it is Income Eligible, with no-cost service and up to 100 percent coverage of insulation costs.
Network membership is the hinge. Energize CT pays its rebate only when an Insulation Installers Network contractor does the work, so put that question to every installer who quotes, us among them, and compare prices after any rebate. For financing, the Connecticut Green Bank’s Smart-E Loan needs no money down and goes up to $50,000 for an owner-occupied one- to four-unit home: 6.99% APR on 5-, 7- and 10-year terms, 7.49% on 12 years, and 7.99% on 15 where a lender offers it. Participating contractors arrange it, so ask. Federal money is out of the picture: the 25C credit covers nothing placed in service after 31 December 2025, so a contractor advertising it on a 2026 job is out of date, and the federal IRA home energy rebates are not available in Connecticut. Our Connecticut rebate guide goes deeper.
Code and climate in Glastonbury
57.9% of Glastonbury’s houses went up before 1980. All of Connecticut is climate zone 5A, and the state code’s climate table lists a winter design temperature of 7 degrees Fahrenheit.
A new house or an addition with an application filed since 1 October 2022 falls under the 2022 Connecticut State Building Code, built on the 2021 International Energy Conservation Code plus state amendments. Its prescriptive minimums: R-60 in the ceiling, with R-49 counting if it reaches full, uncompressed depth over the wall top plate at the eaves; R-30 cavity, R-20 cavity with R-5 continuous, R-13 with R-10 continuous, or R-20 continuous in a wood-frame wall; R-30 in floors; R-15 continuous, R-19 cavity or R-13 cavity with R-5 continuous on basement walls; and U-0.30 windows. The finished house must hold air leakage to 3.0 air changes per hour at 50 pascals in a blower-door test on the prescriptive path, and to 5.0 at most on any path. Its successor, based on the 2024 IECC, has been adopted in draft, but its effective date has been delayed.
Common questions about insulation in Glastonbury
Do you install insulation in Glastonbury, CT?
Yes, across the town: the 1970s to 90s houses of Minnechaug Mountain and the subdivisions around Diamond Lake, the 1950s and 60s capes and ranches, the post-2000 houses with ducts in the attic, and the garrets, cellars and later wings of houses built before 1800. In a condominium such as the Soap Factory Condominiums the building envelope usually belongs to the association, so that conversation starts there.
How much does insulation cost in Glastonbury?
Most projects run $3,500 to $12,500. In a 1980s house the drivers are the attic area, the recessed lights and chases to seal, the cathedral slopes, the floor of any bonus room over the garage, and ductwork sitting in the attic. In a colonial built before 1800 the price depends on what can be reached from the garret and cellar and whether any later wing has walls worth filling.
Are there insulation rebates in Glastonbury?
Yes. Energize Connecticut runs them, and in Glastonbury either the Eversource electric account or the Connecticut Natural Gas account can book a Home Energy Solutions assessment, even for an oil-heated house; the standard copay is $40. Insulation that the assessment recommends, the program approves in advance and an Energize CT Insulation Installers Network contractor installs can earn up to $2.00 per square foot or 75 percent of cost, whichever is less, with a $10,000 cap. Some addresses in town sit in environmental justice areas with a higher rate. A 2026 job carries no federal tax credit.
Our 1980s Glastonbury contemporary has cathedral ceilings and ice at the eaves every winter. What fixes that?
Heat is reaching the underside of the roof. In a cathedral ceiling from that era the batts are usually pressed against the roof deck with no vent space, and the light fixtures and the ridge let warm air straight into the rafter bays. The fix is to stop the air, then insulate the slope properly: either open it and restore a vent path over the insulation, or fill the bay with closed cell foam against the deck so no warm air reaches the cold roof. Which one fits depends on the roof, and we look before we say.
Free estimate in Glastonbury
The free estimate is ours, separate from Home Energy Solutions, and it does not make a house eligible for any rebate. In a house from the 1970s to the 90s most of the visit happens in the attic, among the ducts, chases and light housings, then at the cathedral slopes, the bonus room and the basement rim. In a house built before 1800 we work from the cellar sills up to the garret and say plainly which walls should stay as they are. A written scope and price follow, with no charge and no obligation.
Phone 914-825-6824 any day from 8am to 8pm, or write through the contact form. The Home Insulators has been family-owned since 2015 and is based in New Rochelle, NY; its own 100-plus in-house crew does all of the work, with no subcontractors.
Learn more
- Every Hartford County town we cover
- Rocky Hill, across the river by ferry
- Wethersfield insulation
- East Hartford insulation
- Insulating older homes
- Open cell and closed cell spray foam compared
- Attic insulation