What fiber cement is
Fiber cement siding is made from cement, sand and cellulose fibers, formed into planks, panels and shingles that can look like wood. It's dense, rigid and durable, resists rot and insects, and doesn't melt. It's noncombustible, which makes it a common choice in areas where fire resistance matters.
Advantages
- Durability. Resists rot, insects, impact and weathering.
- Fire resistance. Fiber cement doesn't burn, and many products are used where codes require ignition-resistant materials.
- Dimensional stability. It moves less with temperature and humidity than vinyl or wood.
- Appearance. It can convincingly imitate painted wood lap siding, shingles and board-and-batten.
Trade-offs
- Weight. Fiber cement is heavy and needs more labor to install.
- Installation skill. It must be installed to the manufacturer's specifications to keep its warranty: specific nailing, clearances from the ground and roofs, gaps and flashing at joints, and sealing of cut edges in some cases.
- Painting. Prefinished products come with factory paint; primed products must be painted after installation. Either way, paint eventually needs renewing, though typically less often than on wood.
- Moisture at edges. Cut edges and the bottom edge can absorb water if not handled correctly. Required clearances from soil, decks and roofs help prevent this.
Cutting dust safety
Cutting fiber cement creates dust that contains crystalline silica. Breathing silica dust is a health hazard. Installers should use cutting methods and tools designed to control dust, such as shears or saws with dust collection, and cut outdoors. Ask how the crew will control dust around your home.
Finishes
Prefinished fiber cement comes with a baked-on factory finish and often a separate finish warranty. Primed boards give you unlimited color choice but need field painting soon after installation. Ask which the contractor recommends and what the finish warranty covers.
Behind the siding
Like any siding, fiber cement needs a water-resistive barrier and proper flashing at windows, doors, roof intersections and penetrations. Some manufacturers specify flashing behind butt joints. A replacement project is the time to repair sheathing and update flashing.
Maintenance
- Wash periodically with a garden hose and soft brush.
- Keep caulked joints in good condition.
- Repaint primed or faded siding as needed.
- Keep soil, mulch and sprinklers away from the bottom edge.
Questions to ask
- Are you following the manufacturer's installation instructions for warranty purposes?
- Prefinished or primed, and what's the finish warranty?
- How will you control silica dust when cutting?
- What clearances will you maintain from the ground, decks and roofs?
- Will you replace the water-resistive barrier and flashing?
Styles
Fiber cement comes as lap siding in several exposures and textures, vertical panels for board-and-batten looks, shingles and shakes, and matching trim. Smooth and wood-grain textures are both available. Mixing styles, such as lap siding on the main walls and shingles in gables, is common.
Repairs
Cracked or damaged boards can usually be replaced individually. Prefinished colors may be hard to match on older siding, so ask about touch-up paint from the manufacturer.
Cost and value
Fiber cement usually costs more to install than vinyl because of the material's weight and the labor involved, but it offers durability, fire resistance and a convincing wood look. Ask contractors to break out the cost of removal, sheathing repair, barrier, flashing, siding, trim and paint so you can compare quotes fairly.
Weather during installation
Caulks and paints used with fiber cement need suitable temperatures to cure. Ask the contractor how weather will affect the schedule.