Need to Know: Layout and Installation
Layout: Fiber-cement panels butt together at the edges, making layout a no-brainer. With clapboards and shingles, each course overlaps the next by at least 1¼ inches. The portion that's visible—not overlapped—is called the exposure. (A 6¼-inch-wide clapboard with a 1¼-inch overlap has a 5-inch exposure.) Exposure has to be decided before you order because it determines how wide your siding will be, how much you will need, and how it will look once it's installed.
Installation: Make sure your contractor uses rustproof stainless-steel nails, primes all cuts, and caulks joints with a paintable exterior-grade sealant that will remain flexible. To reduce water absorption, fiber cement has to be installed at least 2 inches above steps, decks, and roofs, and at least 6 inches above grade. Check joints every few years and recaulk as needed.