|Ask Norm: Foil for Attics?|
David: Question: My house on Long Island has an unheated attic that was originally insulated with R-19 fiberglass blankets. I added another layer of R-25 blankets, but I wonder if it would be worthwhile to staple a radiant barrier to the rafters as well. Would this be a cost-effective improvement?
—M. Ackert, Manhasset, N.Y.
Norm Abram Replies: If you lived in a hot climate, I'd say yes. But you don't need radiant barriers where you live, or anywhere else that requires the heat to be on for more months than the air conditioning. This barrier, which is simply a layer of aluminum foil attached to the underside of rafters, prevents heat from radiating into the attic, forcing the air conditioner to work harder. For example, I've read that a radiant barrier in the attic can reduce cooling costs by as much as 12 percent in the Southeast U.S. But Michael Lamb, of the U.S. Department of Energy, tells me you'd be wasting your time—and your money—to install such a barrier in Manhasset. With R-44 in your attic, you should have plenty of insulation; Lamb says Long Island is on the border between the R-49 zones