Attic insulation in New Hampshire: what you need and why
The attic is where a New Hampshire house loses the most heat and where the NHSaves program puts most of its money.
Signs your attic is costing you money
- Ice dams or long icicles along the eaves
- Snow melts off your roof before the neighbors'
- Upstairs rooms are hot in summer and cold in winter
- You can see the ceiling joists above the insulation
- Frost or dark staining on the underside of the roof boards
- The attic hatch is a bare piece of plywood
What a proper attic job includes
- Air sealing first. Every wire and pipe penetration, the top of every interior wall, the chimney chase (with fire-rated materials) and the hatch. This is where the heat leaves; insulation alone does not stop air.
- Ventilation kept open. Baffles at every rafter bay so the soffit vents keep breathing after the cellulose goes in.
- Recessed lights made safe. Covered with fire-rated boxes or replaced with sealed fixtures so they can be buried.
- Blown cellulose to the depth in the scope, usually R-38 or more on top of what is there under NHSaves, deeper if you want to go beyond the program.
- An insulated, weather-stripped hatch cover.
.jpg){kind=link}
The assessment includes an attic inspection with photos, a depth reading and the blower-door number, and the plan shows the rebate line by line.
Questions
How much insulation should a New Hampshire attic have?
Current code for new homes calls for R-49 to R-60, about 14 to 18 inches of blown cellulose. Most attics we open in southern New Hampshire have 3 to 6 inches of old fiberglass, which is R-11 to R-19 at best and less once it has settled or been walked on.
Can you add insulation on top of what is there?
Usually yes, after air sealing the ceiling below it. Old fiberglass is left in place and buried; vermiculite is not, because it may contain asbestos and the program will not fund work over it until it is tested or removed.
Will more attic insulation stop ice dams?
Combined with air sealing and clear soffit vents, yes. Ice dams come from heat reaching the roof deck; stop the heat and the roof stays cold enough for the snow to stay snow.
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.