It's funny how what sounds brand new in new home construction products is really something quite old, but has now come back into vogue. Like the quality and nostalgia of bare hardwood floors, prevalent in our grandparents' home and now the rage in new home installation. Insulation, the material between the walls, is not a popular topic of conversation at cocktail parties these days, but it is similarly undergoing a "throw-back" metamorphosis with cellulose insulation replacing the time-worn fiberglass materials commonly used.

As with any other industry trying to stay on the cutting edge, new home builders are constantly trying to improve their homes with newer, better, and more cost-efficient products. The popularity of cellulose insulation is on the rise with many new home builders because of the wealth of benefits it offers both builder and buyer. What's always amazing to me is that products like this are not really new, but have been around in some form for quite awhile.

Advantages to this product range from fewer air leaks (no, your attic should not be warmer than the inside of your house), to more fire-retardant capabilities, to a better sound barrier, and even pesticide benefits! To understand new trends in cellulose insulation and its good points, let's examine how insulation all started. According to an article in The Lumber Cooperator magazine in 1997, the first person to use insulation was an architect named Thomas Jefferson. And the first insulation he used was cellulose -- on a rather large home in Monticello. The term "cellulose" refers to the base fiber for all plant life; wood, paper, and other plant- based products are all made of cellulose. Those who "think green" would be proud of today's cellulose insulation, however, because it is made up of recycled paper products and treated with boron-based chemicals to make it fire retardant. At the turn of the century, as throughout history, what was important to builders was the availability of raw materials and their by- products. During that time in history the product of choice was wood, so insulation was balsa wool or "balsa batt" (sawdust wrapped in paper) .You can still find balsa wool insulation in some of the old historic homes in the Northeast.

The 1930's saw rise to a by-product from U.S. steel mills. Rock metal slag provided yet another insulation product whose end product was rock wool. The same process of heating and fiberizing was used with another common material- sand, or silica, and the result was fiberglass. When the energy crisis of the 1970's brought more demand for insulation, a resurgence of cellulose insulation grew rapidly. Once the crisis passed, however, only a few companies remained committed to refining the material. Those that did were convinced through their experiences that cellulose outperforms fiberglass.

In the 1990's energy efficiency advocates cited scientific studies reinforcing what these stalwart few companies had maintained all along - that today's non- settling, fire retardant, engineered wood fiber insulation has important performance advantages.

Unlike the "roll out" batting used in attics, cellulose can easily be blown into an attic space with a special machine, filling crevices and areas the average installer would otherwise be laboriously cutting and fitting fiberglass into. In the interior walls, cellulose insulation is mixed with a small amount of water and "misted" into wall cavities the same way. Because of the nature of this dense fiber (it is two to three times more dense than fiberglass batts), cellulose insulation conforms to the space in which it is applied, providing a better seal and blocking airflow fiberglass may have permitted to take place. Of course, blocking airflow is critical to both heating and cooling a home.

Energy efficiency in insulation is measured by "R-values", a term developed by the Federal Trade Commission referring to the rating of "thermal resistance". This was based on an engineering laboratory measurement, the R factor, which is the ability of a material to stop or slow conductive heat transfer through the material itself. Higher R values do not necessarily equate to higher performance, however, because conductive heat transfer is only one of the ways a house can lose energy.

There is much more to the properties of cellulose than I can cite here, but from what I have learned, in the end it is possible to achieve greater comfort, lower energy bills and tighter construction with this denser insulation. Whether cellulose is used in new homes or retrofitted into older homes, it is fast becoming the insulation of choice. For more information on cellulose insulation, you may contact GreenFiber, a Louisiana-Pacific Company and Casella Waste Systems Comapny, which manufactures cellular insulation, and to whom I am indebted for research on this topic. They can be reached at 1-800-0024.

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