Insulation and air sealing in the Upper Valley
Vermont pays up to 90%. New Hampshire pays 75%. For an old house on either side of the river, this is the upgrade with the best arithmetic in the whole program.
Why this is the first thing to do
A heating system can only replace the heat a house loses. In the Upper Valley’s housing stock — capes, colonials, farmhouses, and the attached ells and additions that grew onto them across a century and a half — that loss is enormous and it is concentrated in a handful of places.
The dominant one is the attic plane. Warm air rises, finds every penetration — the chimney chase, plumbing stacks, top plates, recessed lights, the hatch — and leaves. Cold air is drawn in at the bottom to replace it, through the rim joist, the fieldstone foundation, the bulkhead. This is the stack effect, and in a three-story Vermont farmhouse in January it is a powerful engine.
Insulation without air sealing is a common and expensive mistake. Fiberglass batts laid over a leaking attic floor slow conduction but do nothing about the air moving straight through them, which is why a house can be “insulated” and still burn 1,000 gallons of oil.
What both states pay in 2026
| New Hampshire (NHSaves) | Vermont (Efficiency Vermont) | |
|---|---|---|
| Percentage covered | 75% of installed cost | Up to 90% cash back |
| Project cap | $6,000–$8,000 combined, by utility and measure | $7,000 Home Performance cap (was $9,500 before Jul 1, 2026) |
| Audit required first | Home Performance with ENERGY STAR, $100 copay | Yes — assessment gates the rebate |
| Contractor requirement | NHSaves participating contractor | Efficiency Excellence Network member |
| Income-qualified | 100% via Tri-County CAP / Southwestern Community Services | 100% via SEVCA / Capstone Community Action |
| Special case | Liberty gas customers: 100% of air sealing cost | Attic-only measure rebate: $0.50–$1.00 per sq ft |
Nothing else on the board comes close as a percentage. Vermont at up to 90% and New Hampshire at 75% mean a $10,000 envelope project can cost a homeowner roughly $1,000 in Hartland or $2,500 in Enfield. If money is limited and you can only do one thing, this is the thing.
What the work actually involves
Air sealing
Foam, caulk and rigid sealing at every point where conditioned air escapes the envelope. In practice: the top plates where interior walls meet the attic, chimney and flue chases with fire-rated materials, plumbing and wiring penetrations, the attic hatch, recessed light fixtures, the rim joist, and the sill plate above a stone foundation. Done properly it is measured — blower door before, blower door after, and a number you can see.
Attic insulation
Blown cellulose or fiberglass over the sealed attic floor, typically to R-49–R-60 for this climate zone. Baffles at the eaves preserve soffit-to-ridge ventilation so you do not trade an energy problem for an ice dam problem — which matters here, on roofs that carry snow load for four months.
Wall insulation
Dense-pack cellulose blown into the stud bays through holes drilled from inside or outside, then plugged. Most pre-war Upper Valley houses have empty wall cavities. Balloon-framed houses need the cavities blocked at each floor line first, which is also a fire-safety improvement. Not every wall takes dense-pack — brick nogging, existing failed insulation, or knob-and-tube wiring can rule it out until the wiring is addressed.
Basement, crawlspace and rim joist
Often the highest-value square footage in an old house. Spray foam or rigid board at the rim joist stops a startling amount of infiltration. In a dirt-floor cellar — common in this valley — a sealed vapor barrier and insulated foundation walls change the entire moisture and comfort picture of the floor above.
What it costs here
Typical Upper Valley pricing, before rebates:
- Attic air sealing and blown insulation, average house: $3,000–$6,500
- Dense-pack walls, 1,800–2,400 sq ft: $5,000–$11,000
- Rim joist and basement work: $1,800–$5,000
- Full envelope on an older farmhouse: $8,000–$18,000
At Vermont’s 90%, a $12,000 whole-envelope job lands near $1,200 out of pocket. At New Hampshire’s 75% with the cap, the same job lands near $4,000–$5,000 depending on which cap applies. Both are extraordinary numbers by any historical standard.
What to expect for savings
A properly executed envelope retrofit on a leaky old house here typically cuts heating fuel by 20–35%. On a house burning 900 gallons of oil, that is 180–315 gallons a season, every season, indefinitely. The comfort change is usually more noticeable than the bill: rooms that were 6°F colder than the thermostat setting stop being colder, and the draft across the floor at the exterior wall goes away.
The mistake that costs Upper Valley homeowners the most
Hiring a contractor across the state line who is not enrolled in the right program. An excellent insulation crew in Lebanon may have no Efficiency Excellence Network membership, which means a Norwich homeowner who hires them forfeits the entire Vermont rebate — potentially $9,000 — on a technicality that has nothing to do with the quality of the work. Confirm the enrollment before you sign. That is a large part of what we exist to do.
Figures checked July 2026. Rebate programs change their amounts, caps and equipment requirements during the year, and several are capped by available funding. Confirm the current offer with the program or your contractor before you sign anything.
Insulation & air sealing: common questions
How much can I actually get back?
In Vermont, up to 90% cash back on air sealing and insulation, with the Home Performance with ENERGY STAR route capped at $7,000 since July 1, 2026. In New Hampshire, 75% of installed cost with a combined cap generally between $6,000 and $8,000 depending on your utility and measure mix. Liberty Utilities natural gas customers get 100% of air sealing cost covered. Income-qualified households in both states pay nothing.
Do I need an energy audit first?
Yes, in practice, in both states. New Hampshire’s Home Performance with ENERGY STAR assessment costs a $100 copay and is the entry point to the weatherization incentives. Vermont gates its rebates behind an assessment too. It is not a hurdle so much as the thing that tells the contractor what to scope. More on audits.
My house has knob-and-tube wiring. Can I still insulate?
Not the walls, generally, until the wiring is dealt with. Knob-and-tube relies on air around the conductors to shed heat, and burying it in dense-pack cellulose is a fire risk that no reputable contractor will take on and no program will rebate. This is common in pre-1940 Upper Valley houses. The usual path is to rewire the affected circuits first; the attic and basement work can often proceed in the meantime.
Will insulating cause ice dams or moisture problems?
Done properly it prevents them. Ice dams are caused by heat leaking into the attic and melting the underside of the snowpack, which then refreezes at the cold eave. Air sealing and insulating the attic floor keeps the attic cold, which is the fix. What causes trouble is insulation without air sealing, or blocking soffit ventilation with blown material — which is why baffles at the eaves are part of a correct job.
How long does the work take?
Attic air sealing and insulation on an average house is typically one to two days. A full envelope including dense-pack walls and basement work is more often three to five days. The longer part is usually the queue — good weatherization crews in the Upper Valley book out, and autumn is the worst time to start looking. Spring and summer bookings get done before the heating season.
Is it worth doing if I might sell in a few years?
Usually yes, for two reasons. The rebate means your actual outlay is a fraction of the work’s value, and in this market a documented efficiency retrofit with a blower-door number is a selling point — particularly to buyers who have just seen a winter’s worth of oil bills for a comparable house.
The envelope is where the money is
Find out what a full air sealing and insulation job would cost you after rebates at your address.