ROANOKE TIMES
Copyright (c) 1996, Roanoke Times
DATE: Sunday, May 26, 1996 TAG: 9605300009
SECTION: HOMES PAGE: D-1 EDITION: METRO
COLUMN: Hints for Homeowners
SOURCE: STEVE ELDER
The answer to the age-old question ``How much is enough?'' varies according to circumstances, as any graybeard will tell you. When it comes to insulation, too much is when your ceiling caves in.
However, too little is frequently the case, especially if you have an older home. What you should do about insufficient insulation depends greatly on the particular conditions and construction of your home. (And on your level of masochism.)
Insulation practices seem to rouse more controversy than any other single aspect of homebuilding. Wide variations in products, methods of installation and theories of effectiveness make it tough to get the experts to agree. As a practical matter, how you go about improving your home's insulation depends on whether you want to do it yourself or have a professional insulation contractor do it for you.
If you do it yourself, you will probably find it easier to work with fiberglass insulation batts than with loose insulation, which normally requires a blower for installation. There is some good news for do-it-yourselfers: all three major insulation manufacturers now make higher-density, high R-value batts. (``R'' means resistance to heat transfer: the higher the R-number, the better the insulating value.) You can get 31/2- inch batts rated at R-15; R-21, 51/2-inch batts; and R-30, 81/2-inch batts.
Although the fiberglass industry disputes it, a significant body of research suggests that fiberglass is a carcinogen, primarily because it releases small particles of fiberglass during installation. Based on this research the U.S. Occupational Safety and Health Administration has mandated warning labels. The market has addressed this concern by introducing batts encapsulated in a perforated polyethylene wrap in order to prevent fibers from escaping into the air. Owens-Corning has also met the problem of fiberglass irritating the skin by introducing Miraflex, a batt insulation made of two types of glass that twist together and release so few particles that OSHA has excepted the product from the warning label requirement. Miraflex is a nonirritating material that is soft to the touch, making installation less unpleasant.
Batts of insulation work best in attics that have rafters instead of trusses. Trusses have webs that impede movement and make it more difficult to fit the batts tightly. Attics with trusses are better suited to loose insulation, which can be either blown in or poured. Loose insulation is commonly available as fiberglass or cellulose (ground up newspaper treated with a fire-retardant).
Disregard the claims and counterclaims made by the fiberglass and cellulose manufacturers. Both products do quite well, although you will need a deeper blanket of fiberglass to produce an equivalent R-value. It is true that fiberglass does not burn, whereas cellulose will smolder; but tests have shown that cellulose does a much better job of smothering a fire. The risk in both cases is fairly equal; but don't lose sleep over it, since studies have shown that only 3 percent of fires start in framing voids.
The current code requirement for attic insulation is R-30, but most energy gurus are recommending R-38 for Virginia, which does not seem exaggerated in light of this past winter. Whether you do it yourself or have it done, be sure that the insulation does not block any soffit vents. There are special styrofoam baffles available for installation under the roof ply, to provide space for air to move from soffit vents to ridge or gable vents.
Before you undertake to do the attic insulation project yourself, calculate how much insulation you will need, what it will cost, how long it will take you to do it, the irritation factor and the cost of repair after you've stepped through the ceiling. Then get bids from several insulation contractors. You may find the cost difference is not that great.
If you increase your attic insulation to R-38 from R-11, a typical standard about 25 years ago, the payback period can be as short as a year. Normally, I am not an advocate of retro-insulating walls of old houses by drilling holes and blowing in insulation.
Condensation problems can occur between the plaster and the exterior wall due to the lack of an adequate vapor barrier; and the insulation can settle or get blocked by the framing, so that it doesn't fill the cavity completely. However, there is an open-cell polyurethane foam called Icynene that is designed for installation in closed framing cavities. It has an insulating value of roughly R-3.6 per inch of thickness. Call (800) 758-7325 for product and contractor information.) Icynene, along with wet-spray cellulose, requires some expertise and is not regarded as a do-it-yourself product.
Other new products include cotton and wool batt insulation, not yet universally available, and specialty insulation products such as rigid polystyrene or fiberglass boards to use under siding, on foundation walls, or under concrete slabs. Consult your local building materials dealer for prices and availability.
Next time: Cheap ways to tighten up your house.
LENGTH: Medium: 88 linesby CNB