of Home Improvements
*Common Types of Insulation*
There is a bewildering
array of insulations on the market, each product promoted by its manufacturer
as the best. Each may, in fact, be best for a particular application but
certainly not for all. The smart homeowner or builder will use several
different types of insulation in order to achieve optimum thermal performance.
Price and R-value are just two of the characteristics with which we should
This is probably the product that most homeowners think of when insulating their home.
in long rolls and fiberglass batts in 4-foot lengths are both available
in 15- and 23-inch widths, the perfect sizes to fit between joists, studs
and rafters with standard 16- and 24-inch on-center spacings. In this
bound form, the fiberglass is less likely to settle and so is perfect
for insulating regular framing cavities.
Long- Fiber blown
fiberglass is essentially silica, or sand, that has been melted and spun
into fibers. The fibers are coated after cooling with a colored resin
and gathered into blankets of varying density, depending on the desired
R-value and application.Blown fiberglass is chopped into small clumps
with a density of 0.6 pounds per cubic foot. The glass fibers are extraordinarily
resilient and resist settling once their settled density has been reached.
Therefore, when installed at the proper density, blown insulation does
not settle in walls and leave empty heat-convection channels.
Although the binding resin is combustible, the amount of it present is
small enough for the overall product to be considered noncombustible.
Strong points include cost per R-value, inertness and ability to fill
irregular spaces. Its weakest point is low R-value per inch. The best
application is on an open attic floor.
- fiberglass insulation differs from long-fiber fiberglass in size and
length of fibers, and installed density. The fibers and air spaces are
smaller, resulting in a higher R-value per inch than the long-fiber version.
More than twice the amount of material is required, however, leading to
a price that is also more than double. Since the cost of material is usually
a small component in the life-cycle cost of insulating.
is a loose, fluffy, fibrous material intended for blowing into cavities.
It is generally made by finely shredding old newspapers. (Some claim the
finest to be derived from the New York Times, although I believe that's
purely a case of elitism.)
Perlite is a
naturally occurring volcanic mineral containing up to 5 percent water.
When the mineral is crushed and then heated rapidly to its melting point,
the trapped water turns to steam and blows minute glass bubbles. These
highly insulating trapped air cells can be loose-poured, fused into a
rigid board, or substituted for sand and gravel in insulating concrete.
a modified open-cell urethane foam that uses water and carbon dioxide
instead of ozone-depleting fluorocarbon blowing agents. It is applied
either by spray gun to exposed framing cavities or by pouring a slightly
different formulation into existing closed