Loose-fill insulation

To the real estate editor. I invite your attention to two statements in a recent energy column which should be corrected. These are:

* (With reference to loose-fill insulation) -- ". . . if poured onto the floor, loose- fill insulation can easily be blown about the attic. In other words, it may not stay in place."

* "Insulation experts say it is much more difficult to get an R-value figure with a loose-fill product."

It has never been a reported problem with respect to cellulose insulation, which, after a short period of normal moisture cycling, takes a "set" and will be very stable in an attic.

It must be remembered that there is a substantial difference in density between loose-fill fiber glass, which is blown in at a theoretical maximum of 0. 7 pound per cubic foot (but which in actual practice may be as little as 0.3 pound per cubic foot) and cellulose insulation, which is applied in a range of densities from 2.0 to 2.4 pounds per cubic foot.

With respect to "getting an R-value" with loose-fill vs. batts and blankets, a Department of Energy report made after a 2 1/2-year study of the thermal properties of fiber glass and rockwool batts and blankets reached the conclusion that in addition to being substantially overrated in R- value, the dimensional stability of the products needed substantial improvement.

The conclusions of that report were that length, width, and thickness varied widely.

Under these conditions, it is not only impossible to assure a homeowner of a uniform R-value with a batt or blanket because of variations in thickness, but also when placed between joists or sidewall studs, they may allow for air infiltration, which is the big advantage that loose-fill insulation has over these other forms, because it does fit snugly with the studs and joists. Bill Mac Kenzie Cellulose Manufacturer's Association Bailey's Crossroads, Va.

If you have a question n how to save energy -- in your home, your car, on the water -- send it to ENERGY, The Christian Science Monitor, One Norway Street, Boston, MA 02115.m