Insulation and air sealing for Harpswell homes: attics, crawl spaces, rim joists and walls, starting with a free assessment of the R-value you actually have. The typical home here dates to the late-1970s, and 20% of its 4,286 homes went up before 1940.
Harpswell runs to about 24 square miles and roughly 5,046 people. It sits about 15 miles east of downtown Portland. There are around 4,286 housing units here. The community dates back to 1775. We cover ZIP codes 04079, 04066 and 04003.
We have not logged a completed job in Harpswell yet. We would rather say so than put a number on this page that is not real.
The typical home in Harpswell dates to around the late-1970s. Postwar building here often meant three or four inches of fiberglass and no attempt at air sealing. If nobody has touched it since, that is what is still up there.
We work across Harpswell rather than one corner of it — Bailey Island, Orr's Island, Cundy's Harbor, Harpswell Neck, Sebascodegan Island, Harpswell Center, East Harpswell, North Harpswell, South Harpswell and West Harpswell included. Construction and vintage change between them, sometimes by thirty years and a whole different framing method, which decides whether a wall can be dense-packed at all.
Harpswell is Harpswell Neck plus three large islands linked by bridges, Sebascodegan (Great Island), Orr's Island and Bailey Island, and 95 smaller islands, with about 216 miles of Casco Bay coastline. It leads Maine in active lobstering licenses, and the Bailey Island Bridge, built in 1927 and 1928, is thought to be the only cribstone bridge in the world.
The Census Bureau estimates 4,286 homes in Harpswell. 864 of them (20%) went up before 1940 — 21st of 64 places on this site for pre-1940 housing. More of today's homes date from before 1940 than from any single decade since, and 51% predate 1980. For Cumberland County as a whole the pre-1940 share is 23%, so Harpswell sits below it.
Of 2,598 occupied homes, 1% heat with utility gas and 7% with electricity; another 34% burn propane or other tank gas. Electric heat here is less common than across the county (15%), and ranks 40th of 64 on this site. The heating fuel does not change the Efficiency Maine rebate, but it does change what each inch of insulation is worth, which is why the boiler, furnace or heat pump is the first thing an assessment looks at.
83% of occupied homes are owner-occupied and 91% of all homes are single-family detached houses, with 199 mobile homes in the count. Read together, those numbers point toward the attic, which is where most houses here start.
| Built | Homes | Share | |
|---|---|---|---|
| Before 1940 | 864 | 20% | |
| 1940s | 114 | 3% | |
| 1950s | 271 | 6% | |
| 1960s | 301 | 7% | |
| 1970s | 650 | 15% | |
| 1980s | 801 | 19% | |
| 1990s | 454 | 11% | |
| 2000s | 467 | 11% | |
| 2010s | 274 | 6% | |
| 2020 or later | 90 | 2% |
4,286 homes, Census ACS 2020–2024 (B25034, B25040, B25003); 2,598 occupied.
1,255 of Harpswell's 4,286 homes (29%) were built in the 1980s and 1990s. The gaps in houses of that age are the parts nobody sealed: batts stuffed into the rim joist, bare spots over cathedral and tray ceilings, soffit vents buried with no baffles, can lights punched through the ceiling plane. A top-up plus a day of sealing usually covers it.
Harpswell enforces the Maine Uniform Building and Energy Code (2021 IECC with Maine amendments). Harpswell's inspection notice (revised April 18, 2025) lists the 2021 IECC as part of the state code, and the town's permit application asks for radon and blower door results on every new home.
For new work, the attic number under that edition is R-60, with walls at R-30, or R-20 + R-10 continuous, or R-13 + R-15 continuous, or R-20 continuous. Set that against the Department of Energy, which recommends R60 for an uninsulated attic in this climate zone and R49 for one that already has a few inches.
The 2021 IECC, Table R402.1.3, zone 6, as amended by Maine's energy rule, 08-003 C.M.R.
Harpswell publishes no answer either way. Insulation and air sealing appear on neither the permit-required list nor the exempt list. Harpswell's 2025 permit flyer says permits are needed to enlarge, alter, repair, renovate, remodel or update an existing structure; it does not name insulation, so ask before the job is booked. We confirm it with the department before we start and pull whatever is needed. We would rather write that here than guess on your behalf.
The published number is 207-833-5771. The department page is here.
Permitting is on us, not on you.
Heating fuel in Harpswell, by the Census Bureau's count: fuel oil or kerosene in 44% of occupied homes, electricity in 7%, propane or tank gas in 34% (Census ACS 2020–2024). The insulation money for a Harpswell house comes from Efficiency Maine, not the electric company. For a zone of 500 square feet or more it pays $2,000 at any income, $3,000 at moderate income and $4,000 at low income, and $150 to $300 more for attic air sealing. Only a Residential Registered Vendor can do rebated work, the claim goes in within six months, and a lifetime limit of $8,600 per home applies. Income-qualified households in Cumberland County can apply to Community Concepts Inc (207-795-4065) for free weatherization through MaineHousing instead. See the rebate guide for the tiers and the checklist, and the Cumberland County page for the county.
Every layer of an insulated attic, explained
Harpswell borders Brunswick, West Bath, Phippsburg, Freeport, Chebeague Island and New Meadows River. These are the ones we also cover, each with its own energy code and permit rule:
Elsewhere in Cumberland County we also cover:
Maine sets the residential energy code statewide, so the attic figure is R-60 wherever it is published here; what changes is the permit desk, and 3 of the 7 publish a permit rule for insulation.
| City | Energy code | Attic R required | Permit to insulate | Building dept. |
|---|---|---|---|---|
| Harpswell | Maine code, 2021 IECC | R-60 | Not published | 207-833-5771 |
| Brunswick | Maine code, 2021 IECC | R-60 | Not published | 207-725-6660 |
| West Bath | Not published | — | Not published | 207-443-4342 |
| Phippsburg | Maine code, 2021 IECC | R-60 | Yes | 207-389-2653 |
| Freeport | Maine code, 2021 IECC | R-60 | Not published | 207-865-4743 |
| Baldwin | Not published | — | Not for an attic top-up | 207-625-3581 |
| Bridgton | Maine code, 2021 IECC | R-60 | Not for an attic top-up | 207-803-9963 |
All 25 Cumberland County jurisdictions side by side →
Harpswell enforces the Maine code, 2021 IECC, which sets R-60 for an attic in new work. That code also reaches work on existing houses, not only new ones.
Harpswell publishes no rule either way, so we ask its building department at 207-833-5771 before the job is scheduled.
The statewide Efficiency Maine rebates: $2,000 to $4,000 per insulated zone of 500 square feet or more, by income tier, and $150 to $300 for attic air sealing; the work has to be done by a Residential Registered Vendor and the attic has to start at R-21 or less. The federal 25C credit ended for work placed in service after December 31, 2025.
The typical home in Harpswell dates to around the late-1970s; the Census Bureau's 2020-2024 median year built is 1979. Of its 4,286 homes, 20% went up before 1940 and 19% in 2000 or later. It is a median for the place, not a survey of individual houses.
Code and permit facts checked October 24, 2026, rebates October 24, 2026; housing: Census ACS 2020–2024. Sources: harpswell.maine.gov (2, 3, 4, 5, 6, 7, 8, 9, 10, 11) · maine.gov (2) · en.wikipedia.org (2) · zip-codes.com · tigerweb.geo.census.gov · efficiencymaine.com (2, 3, 4) · energystar.gov · data.census.gov. These change; confirm with the building department at 207-833-5771 or Efficiency Maine at 866-376-2463 first.
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