They cost about $50 apiece more than wood or steel, but Holiday Builders in Melbourne, Fla., installs smooth-surface fiberglass entry doors on all of its single-family homes.

Wood doors, says corporate purchasing director Scott Clark, can warp and rot in Florida's steamy climate. And steel doors, he notes, can dent and rust.

Indeed, because smooth fiberglass entry doors resist dents, dings, rust, and warping, they have become the fastest-growing segment of the entry door market, says John Kufner, general manager of entry products for manufacturer Therma-Tru. Fiberglass entry doors, including smooth and textured products, claim 15 percent of the market, up from 10 percent at the turn of the century, shortly after smooth fiberglass was introduced. This makes smooth fiberglass doors one of our top innovations since 1990, the year BUILDING PRODUCTS was founded.

Production builders, partial to sturdy, affordable steel doors, typically turn to more expensive look-alike smooth fiberglass to keep construction costs down once they tire of replacing steel units scratched and dented during deliveries of appliances and other heavy building products to the jobsite. Clark says that's what swayed him to switch three years ago. Since then, he has used smooth fiberglass doors on 8,000 homes.

The climbing price of steel during the past couple of years has narrowed the price gap between steel and fiberglass, luring more converts to the composite doors, which mingle fiberglass, resins, and fillers to form panels that manufacturers claim are 10 times more resistant to dents than steel and about 10 times less likely to rust, even on a beach house.

Most manufacturers' fiberglass doors are firerated and some even pass Dade County, Fla.'s stringent tests for impact resistance during hurricanes.

Still, some builders consider smooth fiberglass doors a commodity product best reserved for low-priced tract homes.

One builder says printing his company's name in an article about smooth fiberglass doors could ruin the firm's reputation as a high-end builder.

“It's not decorative enough for our communities,” says the builder, who notes he puts smooth fiberglass doors only on lower-end and multi-family homes. “When you go to a raised-panel, textured product, fiberglass is more decorative.”

But John Monfore, product marketing manager for exterior doors at manufacturer Jeld-Wen, says smooth fiberglass doors are penetrating the move-up market.

He points to an increasing interest among builders in Atlanta neighborhoods, where $600,000 to $700,000 homes show off painted steel doors. Even there, he says, “Fiberglass is starting to take away from steel.”

Kufner adds that Therma-Tru distributors are selling smooth fiberglass doors to more custom builders and remodelers. But the product's mainstay, he concedes, is production housing, especially in communities designed for families.

And in the remodel market, notes Kufner, “Families with children are driving the use of smooth fiberglass.”

Monfore predicts that nationwide, smooth fiberglass will claim up to 20 percent of the entry-door market within five years as the largest production builders opt to install them on nearly every new home.