Merle Henkenius, Popular Mechanics

Vinyl siding expands when it's hot and shrinks when it's cold -- and not just a little. A 12-foot panel can expand up to 3/4 inches on a hot day and a 30-foot panel, 2 inches or more. This simple fact influences everything: from vinyl's appearance to its installation particulars. Most of all, it means you need a skilled installer.

Because of expansion, vinyl siding must not be tightly nailed or fitted. Every piece needs at least 1/4 to 3/8 in. of slack at both ends, and nails must be driven in straight. Pieces longer than 25 ft. can expand too much and pieces shorter than 2 ft. can sag.

When it comes to installers, the best promise of quality is a history of quality. Be cautious of contractors who subcontract. Look for an experienced, on-the-job installer who is eager to show you past work. Keep in mind that properly installed vinyl has a generally loose appearance. Signs of poor work are bulges, warps and separations in the siding, sags in vinyl soffit and ripples in aluminum fascia.

Workmanship warranties in construction typically last only one year, and most installation problems will become apparent during that year. Still, a three- or five-year workmanship guarantee is better. Many of the installers we spoke with offer lifetime warranties that match the product warranties. If you expect to move within a few years, basic siding and the low bid can make sense. If you plan to stay, premium siding and a careful crew is a better investment.

Vinyl siding contractors are usually replacement window and gutter contractors, too, so you can order a fairly extensive exterior overhaul. While prices vary regionally, we found vinyl siding starting around $275 per square (100 sq. ft.), installed. This includes 1/2-in. foil-faced sheathing, a medium-quality siding and all necessary trim. In contrast, installed premium siding in an upscale market could easily run $400 per square. New soffit, fascia and window channel are priced separately. Vinyl soffit, for example, runs $2 to $7 per linear foot, depending on width.

Based on these estimates, siding a simple 10-square ranch house -- about a 1,200 sq. ft. home -- could cost as little as $3,000 or as much as $6,000. Replacement windows could easily add several more thousand. A siding, soffit and fascia installation on a larger suburban two-story, in the same market, could easily run to $15,000.

These are retrofit prices. New home installations are generally a little less. While vinyl can be pricey, a standard installation doesn't come close to the cost of wood or masonry, and is only slightly more expensive than hardboard siding. When you factor in painting and repainting, vinyl can be less expensive than hardboard.

Because vinyl should never be face nailed, and because gutters are usually nailed through the fascia, most fascia wraps are made of painted aluminum that's formed on site. Existing gutters must be taken down to accommodate the new fascia, so this would be a good time to install new gutters if that's what the job requires.