Fiber cement siding ("fibre cement cladding" in the UK and "fibro" in Australia) is a building material used to cover the exterior of a building in both commercial and domestic applications. Fiber cement is a composite material made of cement reinforced with cellulose fibers. Originally, asbestos was used as the reinforcing material but, due to safety concerns, that was replaced by cellulose in the 1980s.
Fiber cement cladding is a very heavy product and requires two people to carry the uncut sheets. Thin fiber cement cladding is fragile before installation and must be handled carefully because it is prone to chipping and breakage if improperly handled. Once the product is cut it may again require two people to install – one to hold the sheet flush against studwork and the other to nail the product in place.
Cutting fiber cement sheeting can be cut to size in three ways:
Thinner sheets can be scored with a heavy duty cutting blade and snapped
Using a hand- or electric-powered "fibro cutter" (Australian term)
A mechanical saw using a diamond blade (masonry blade) is needed to cut thicker and denser sheets
When hanging fiber cement sheets, an approximately 5-millimetre (0.2 in) gap is required between end-joints (cladding seams), later to be filled with caulking made for fiber cement siding. Metal step flashing is required behind overlapping seams to prevent sheathing damage from water. Hot-dipped galvanized roofing nails are used to secure the sheets.
Some caution must be exercised to properly ventilate areas where fiber cement siding (FCS) is being cut; long-term exposure to the silica dust generated during the installation process can cause silicosis.
Fiber cement cladding can be painted or stained before or after installation. For areas of exposure, weatherproof paint must be used. Once the product is fixed the joints are usually covered with timber battens and the entire wall surface is painted.