Like all siding materials, fiber cement has a learning curve. With a few simple steps, however, you can achieve excellent results on a consistent basis. Here are the biggest mistakes to avoid:
Improper fastening. By far the most common error. Most manufacturers recommend setting your nails flush with the surface of the piece and snug to the wall. “I've seen brand new, blind-nailed sided houses where you could pull the siding off with two fingers,” says Mark Parlee, owner of Parlee Builders, in Des Moines, Iowa. Eliminate this by using the proper nail gun; that is, one with a depth-of-drive adjustment. Turning down the compression will also help, but it may not be enough. Another option is to hand-nail or screw the pieces on. Both will increase labor burden but help you avoid this mistake.
Fitting pieces too tightly to trim or to each other. This may seem like a good idea, but it often results in the piece(s) bowing during expansion, causing unsightly waves. It's especially noticeable on long straight walls. Avoid it by leaving a 1/16- to 1/8-inch gap where the siding butts the trim and apply high-quality sealant to the gap. This will allow the siding to expand and contract without bowing.
Not nailing on the studs. A huge no-no. Fiber-cement siding is heavy (2.2 pounds per foot). Not hitting the studs is a recipe for disaster in high-wind areas. Always nail the siding on the studs for the best result. If nailing on the studs is not possible, try using an off-stud joiner to help keep the pieces together.
Incorrect fasteners. Most fiber-cement siding manufacturers will void the warranty if you use staples to fasten. Nails or screws are the preferred method. Ring-shanked nails will give you increased holding power. And several companies make screws specifically for fiber-cement siding installation.
Improper overlap. “Too little lap and you have a weather issue,” says Jim Glover, of Glover Construction in Pierre, S.D. “Too much and the siding doesn't lay flat, which can lead to buckling, rattling, and a poor appearance.” Manufacturers suggest a maximum overlap of 1¼ inches. More may result in the piece kicking away from the underlying piece instead of laying flush.
Following these tips along with the manufacturer's installation instructions will help you make every job a success. —Carl Sperry is a California contractor.