QWhat can you tell me about radiant barriers, which I'm told are the most efficient of all insulations? -- S. Brown

ATests have shown that radiant barriers can be effective in cutting cooling costs, especially in warm climates. They work differently than conventional insulation, and are generally are used in combination with it.

A radiant barrier is a thin sheet of material, usually coated on one side with a reflective surface such as aluminum. The barrier, when properly installed in an attic, helps prevent heat that penetrates the roof of a home from reaching the living area. In a typical installation, the barrier is stapled to the underside of the roof rafters with the reflective surface turned up.

According to an Energy Department fact sheet, a radiant barrier used in an attic with R-19 floor insulation, which is about six inches of fiberglass, can reduce annual cooling costs by 2 to 17 percent, depending on a variety of factors. The conclusion is based on "numerous field tests" that also show that radiant barriers can "also possibly" cause some reduction in heating bills.

The Energy Department fact sheet offers a great deal of information on radiant barriers, including details about tests, and can be accessed at the Web site www.ornl.gov/sci/roofs+walls/

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What cleaner should be used on plastic outdoor furniture?

-- D. Stockton

The cleaner usually recommended by manufacturers is a "mild detergent," such as dishwashing detergent, in warm water. Use about 1/4-cup of detergent to a gallon of water and apply with a soft brush. Rinse with clear water. Either colored or white furniture can be cleaned with this solution. If detergent doesn't get the furniture clean, try a solution of chlorine bleach (one or two cups of bleach to a gallon warm water). However, bleach should be avoided if possible.

The furniture can also be cleaned with a pressure-washer set at low pressure.

A light coat of automotive wax will help make new or just-cleaned furniture easier to clean.

Suntan lotion contains chemicals that can damage plastic furniture. Spread a towel over the plastic to protect the surface when using lotion.

Fortunately, outdoor furniture made of plastic is often so inexpensive that it can be replaced if there is severe staining or damage. I own a couple of comfortable Adirondack chairs that cost less than $10 each.

I recently had my roof reshingled. The asphalt shingles were installed without a metal drip edge. Is a drip edge a good idea and can I install it myself? -- I. Kamensky

It is standard procedure to use metal drip edge or drip cap when a roof is shingled. The L-shaped drip edge protects the rim of the wood roof deck from water and potential rot. The cap also helps give the roof a neater appearance. One flange of the L should be under the shingles, the other overlaps the fascia or trim.

Drip edge is easy to install before the shingles are in place, but a retrofit installation can be complicated. For one thing, drip edge along eaves should be installed under the underlayment or "tarpaper" beneath the shingles. Rain gutters can also get in the way of retrofit installation on roof eaves. Attempting a retrofit installation along the eaves would be difficult and might do more harm than good.

If you feel you can safely work from a ladder, you might be able to install drip edge along the rakes, or sloping edges of the roof gables. Aluminum drip cap is sold in strips at most home centers. Slip the long flange of the drip edge under the shingles and nail to the fascia boards with aluminum trim nails (in a proper installation, the nails should be under the shingles). The job will be easier if you cut the drip edge into three-foot or four-foot lengths. Overlap the ends of the strips by a couple of inches, shingle style, so water can't get under the drip edge as it runs down the roof.

The contractor that shingled your roof should have taken care of this project as part of the job.

Questions and comments should be sent to Gene Austin, 1730 Blue Bell Pike, Blue Bell, Pa. 19422. Send e-mail to doit861@aol.com. Questions cannot be answered personally.