Having the attic air sealed and insulated

Sealing the air leaks in the attic and adding insulation saves an average of 15 percent on heating and cooling costs. Nine out of 10 homes in the U.S. are under-insulated. Attic sealing and insulation is contractor work.

What you need

• Your climate zone
• How many inches of insulation the attic floor has now, if you know it, or the contractor can measure it
• The kind of attic access: a hatch, pull-down stairs or a door
• The rough size of the attic floor in feet, such as 24 by 32

Steps

1. 1

   Look up your target R-value

   With 3 to 4 inches already in place, the target runs from R25 in Zone 1 to R49 in Zones 4 to 8. An uninsulated attic needs more, from R30 in Zone 1 up to R60.

   10 min

2. 2

   Call the utility first

   Your gas or electric utility may offer rebates for the work, and some post pre-screened lists of licensed and insured contractors.

   15 min

3. 3

   Call several contractors

   A good contractor is licensed in your state, insured, and trained and certified for insulation work. The Building Performance Institute (BPI), which certifies contractors, and ENERGY STAR's Home Upgrade providers both list them. Tell each one the age of the house. Homes from the 1930s and earlier can have knob and tube wiring, a fire hazard where it touches insulation.

   30 min

4. 4

   Confirm "seal before insulating"

   The contractor should seal the attic's holes and gaps before any insulation goes in.

   5 min

5. 5

   Compare the estimates line by line

   Each estimate should include insulation baffles, which keep the soffit vents clear, and weatherstripping and insulation for the attic hatch. Older recessed lights that stick up into the attic need sealed covers before insulation goes over them.

   20 min

6. 6

   Plan the safety test

   If a gas furnace or water heater sits in the attic, have a heating contractor run a combustion safety test after the air sealing.

   5 min

7. 7

   Check the paperwork at the end

   The contractor should give you a record of how much insulation was added and the attic's new R-value. Check it against your target and file it with your home records.

   5 min

What the contractor may find

Some problems need a professional fix before the insulation goes in:

• Wet or damp insulation, a sign of a roof leak
• Moldy or rotted rafters or joists, a sign of moisture problems
• Kitchen, bath or dryer vents blowing moist air into the attic instead of outdoors
• Little or no attic ventilation
• Knob and tube wiring

Old insulation can usually stay, with new insulation added on top, unless it's wet, moldy, smelly or holds animal waste.