Hardibacker board is cut by scoring a line in the board and then snapping the board along the line for straight edges. To cut curves, a tungsten-carbide jigsaw blade is used. All jigsaw cuts and drilling is done outdoors, and an N95 dust mask is worn to avoid inhaling silica.
- Mark the cutting line
Use a construction pencil to make a mark on the board along the cutting line of the board. For straight cuts, a mark can be placed on both sides of the board to aid in cutting with the scoring tool.
- Score the surface of the board
Place a straightedge along the cutting line. Run a scoring tool designed for use with fiber-cement backerboard along the edge of the straightedge's edge for five or six passes to cut halfway through the board.
- Snap the board
Hold the side of the board to be used against a stable surface, and then pull the waste side upward towards the scored line to snap the board along the line.
- Cut curves in the board
Mark the board with a construction pencil in the curve desired. Drill several small holes along the line with a 3/8-inch carbide-tipped masonry drill bit to aid in turning the jigsaw along the curved line. Place the jigsaw blade through the first hole at the beginning of the curved line, and then cut through the board along the line.