Ask contractors who install seamless vinyl — i.e., siding panels 40 feet long — what they like about the product and they're sure to mention the look. The length of the panel —slightly more than three times that of traditional siding — means it provides an unbroken plane across the walls of most houses.

Proponents also claim installation is easier, allowing for fewer mistakes. Panels are attached with a free-floating clip system, which Clark Brockman, of Exterior Innovations in Savannah, Ga., calls “dummy-proof.”

Price Difference Contractors who install the patented product say a siding job in long vinyl panels will cost 10% to 15% more than vinyl of conventional length. Yet homeowners many times prefer it. Mike Hutchinson, president of Midwest Seamless Vinyl Siding in Des Moines, Iowa, who's carried seamless vinyl since 1992, sells both products and says he sees a clear customer preference, which is why 85% to 90% of his siding jobs are in long panels. “Nobody wants those seams all over the house,” he says.

Brockman, whose market includes owners of everything from mobile homes to mansions, says the product has enabled him to penetrate upper end neighborhoods where he had little success marketing vinyl in traditional lengths.

In Minneapolis, Ken Wolfbauer, president of Seal Guard Systems, a replacement company that's carried long panel vinyl for six years, says his big competitor when bidding seamless vinyl jobs is seamless steel. He argues that although uncoiled steel may be seamless, vinyl better mimics the look of wood. “Steel siding looks like steel siding,” Wolfbauer says. “If you want the look of painted redwood, seamless vinyl siding is the way to go.”

Pros and Cons Apart from appearances, contractors maintain that lack of seams reduces points of entry for wind, moisture, and insects. Downside? The sheer length of the product makes it impossible to transport in a pickup. Installation requires at least a two-man crew.

“One guy can't do it by himself,” Hutchinson says. “You've gotta have two or three guys on the job. And there's more prep work.”

Seamless vinyl is installed through a network of contractors licensed by Seamless Siding Management Corp., in Randolph, NJ., Gerald Damora, president, says he carefully scrutinizes contractors seeking to join. “You'd rather have the FBI and the CIA looking at you,” Damora says jokingly.