Earlier this year, Bill Conforti, president of Siding-1 Inc. and Windows-1 Inc. in Chicago attended several seminars on fiber-cement siding. Like many companies that install primarily vinyl, Siding 1 is interested in adding fiber cement to their repertoire. Conforti likes the product, but he has reservations about accessories.

The use of fiber-cement siding is growing in both remodeling and new construction. Manufacturer estimates put fiber cement at 10% of the siding market. "Most contractors like it, because it looks great and allows you to make more money," says Michael Strong, vice president of Brothers Strong, a full-service remodeler in Houston. The look and durability of fiber cement, says Strong, makes a complete siding job an easy upsell with, for instance, additions.

But many wonder if the product's popularity would be even greater if accessory items such as inside and outside corners, soffits, fascia, and j-channels were fully available in fiber cement. Certain fiber cement manufacturers produce accessories as well as siding planks, but some installers find them unavailable, overpriced, or otherwise unsatisfactory and use an alternative material -- vinyl, aluminum, wood, or wood composites -- for trim.

"We use aluminum for soffits and fascia," says Beth Lappin of Boss Construction in New Lennox, Ill., a siding company that now does about a quarter of its volume in fiber cement. Phil Coates, a sales estimator for A Cut Above Windows and Siding in Portland, Ore., says his company's crews use a mixture of cedar, vinyl, and masonry to trim fiber cement jobs.

But using another material along with the fiber cement can cause problems. Because some fiber cement companies offer a 50-year warranty on the product, faulty installation or use of accessory items in a material that deteriorates more rapidly than the siding itself can cause problems down the road. Some manufacturers of vinyl accessories -- though not all -- warranty their products for the life of the fiber-cement siding.

Scott Barr, general manager of Southwest Exteriors in San Antonio, says the fiber cement manufacturer he uses supplies all necessary trim items. "We use it for windows, doors, and corners," he says. And though using the manufacturer accessory items is more expensive, Barr says it's worth it to have a whole system. Previously, Southwest Exteriors used vinyl trim and accessory items for fiber-cement siding. To forestall warranty headaches, Barr advises installers using accessories made of wood, vinyl, or other materials to "manage the customer's expectations. Let them know the risks of not doing everything" in fiber cement and set that forth in the contract.