Air sealing explained: where the heat really goes
Drafts, cold floors and a furnace that never shuts off usually come down to leaks, not equipment.
The stack effect, in one paragraph
Warm air rises. In winter it leaks out through the top of the house, through the attic hatch, top plates, chimney chase and recessed lights, and every cubic foot that leaves pulls a cubic foot of cold air in at the bottom, through the rim joist, the sill and the basement windows. The house becomes a slow chimney. You feel it as drafts and cold floors; you pay for it on every oil delivery.
Where we seal
- Attic floor: top plates, wire and pipe holes, the hatch, duct chases, dropped soffits over kitchen cabinets
- Chimney chase and flue penetrations, with sheet metal and fire-rated sealant
- Recessed lights, covered or replaced
- Rim joist and sill with closed-cell foam
- Basement windows, bulkhead door, pipe and wire entries
- Weather-stripping on exterior doors and the attic access
Why the program pays all of it
NHSaves covers 100% of air sealing on qualifying homes because it is the most cost-effective measure there is: a day of work that cuts fuel use by 10 to 20% on its own and makes every inch of insulation work better. It is also the measure homeowners can least do themselves, because the leaks are in places you cannot reach or see.
A home energy assessment answers it with numbers: a blower-door test, an infrared scan and a written plan with the NHSaves rebate worked out. No pressure, no sales visit.
Questions
What is a blower door?
A fan mounted in an exterior doorway that pulls air out of the house while a gauge measures how much leaks back in. The result, in cubic feet per minute at 50 pascals, is the house's leakiness number. We test before and after so you see the change.
Can a house be too tight?
Yes, and the program guards against it. Every assessment calculates the ventilation the house needs for its size and occupants; if sealing would take the house below that line, we add a properly vented bath fan or a fresh-air inlet. Combustion safety is tested too.
Is air sealing the same as caulking windows?
No. Window caulk is worth doing, but the big leaks are at the top and bottom of the house: the attic floor and the basement rim joist. That is where the stack effect drives air through in winter.
Related
Let's take a look at your house.
It starts with a phone call at no cost. We tell you plainly what the house needs, what NHSaves will cover and what the rest will cost, in writing, before anything is scheduled.