Fiber cement siding is made of Portland cement, wood pulp, and fine sand. Many people call this material Hardiplank, although that is not strictly correct. Hardiplank is the trademarked name of one specific manufacturer’s fiber cement siding. However many people use the name interchangeably with the actual product, like some people ask for a Kleenex, not a tissue. Be sure, when purchasing fiber cement siding, that you are aware of the difference, and carefully research and follow your manufacturer’s instructions when it comes to the installation of your siding.
Below are several methods of cutting fiber cement siding. Which method you use will depend on the tools you have at hand, the amount of cuts you must make, and any instructions that your manufacturer has offered. No matter which method you use, wear a face mask or respirator when cutting Hardiplank or any fiber cement siding product to protect your lungs from the resulting silica dust.
Cutting Fiber Cement Siding with A Scoring Knife
People who have cut drywall before will probably be familiar with this method for cutting Hardiplank and other fiber cement boards.First, carefully measure the siding and use a pencil and straight edge or carpenter’s square to mark the cut line. Next, place a metal straight edge against the cut line, with the metal straight edge covering the end of the Hardiplank that you want to preserve.
Cutting Hardiplank with a Circular Saw
Hardiplank and other fiber cement sidings cut well with a circular saw fitted with a carbide tipped blade. Hardiplank also sells saw blades made specifically for cutting Hardiplank. Both will create an even, smooth cut; but expect to replace your blades frequently.
Contractors who cut fiber cement have noted that the silica dust seems to affect the saw motor after extended use. You may want to purchase a circular saw and designate it for cutting the fiber cement boards. Remember that the dust created by cutting fiber cement is toxic; be sure to wear a respirator and use a dust collection system if available.
Cutting Fiber Cement with an Electric Shear
An electric shear makes the most exact cuts, but is a fairly expensive piece of equipment. Expect to spend $500-$800 for a good electric shear: contractors that specialize in fiber cement siding often use them for angled cuts. Fiber cement cut with an electric shear also produces far less dust, making it a safer tool to use.