Check Forced Air Ducts for Cooling Leaks

Even if its walls and roof are insulated, your house may be losing energy--through its heating and cooling ducts.

Here are some insulating tips for making duct systems more enery-efficient, from Bob Vila of PBS’s “This Old House” program, and Owens-Corning Fiberglas Corp., Toledo, Ohio.

Locate ducts and tape all sheet metal joints tightly with aluminum pressure-sensitive tape so conditioned air won’t leak out.

Wrap ducts with 2-inch glass fiber duct wrap insulation, using large shears, a tape measure, pen, straight edge, and tape, as follows:


--Mark off on the wrap facing a length equal to the duct’s perimeter plus 8 inches if duct is rectangular (12 inches if round). Cut wrap along this line, removing 2 inches of glass fiber at one end to leave a flap of facing.

--Wrap insulation around duct with foil side out, butting both ends together and overlaying facing flap on other end.

--Tape the seam lengthwise, and continue cutting and wrapping as you move along duct. Butt each piece of insulation tightly against the next piece with foil overlapping, and tape these joints all the way around.