How to Cut Cement Board in 4 Steps (With and Without a Saw)

Cutting cement board kicks up a lot of silica dust, which is dangerous to breathe and a pain to clean up. Work in a well-ventilated space or outdoors, if possible.

If you must cut cement board indoors, secure plastic sheeting over entrances to the room with painter’s tape and close all vents to limit dust moving through the air in your home. Lay a drop cloth or plastic sheeting on the floor to reduce cleanup. Cover your vanities, toilets, and other furniture and large items with plastic sheeting, too. 

Put on protective clothing, including work gloves, safety goggles, and a sanding respirator, when cutting cement board. Wearing a sanding mask is critical, even if working outdoors or in a well-ventilated space. The silica dust from the board can cause lung irritation and shortness of breath (or worse with prolonged exposure).

Beyond gear, follow safety precautions when working with knives and saws. Always follow the proper safety guidelines for power tools.

Draw a line with a pencil to mark where you want to cut, or place a straightedge along the line. 

Utility Knife (Best for Full-Length Cuts)

Press down the straightedge and move the utility knife blade along the line. Turn the board carefully to follow the same line from the other direction. Score the line again. You may need to score the board several times, depending on its thickness and the sharpness of your blade.

Safety note: Blades can be very hot after cutting, so place them in a safe spot to cool before throwing them in the trash. You may go through several knife blades when making cuts. 

Circular Saw (Best for Partial Cuts or Large Projects)

Use a circular saw with a masonry cutting disc for cuts that don’t extend the length of your material or for large-scale projects where you’re making dozens of cuts. Power saws work faster but create more dust, so stick with a utility knife if you’re making just a few cuts. 

Place the cement board face down on a pair of sawhorses. Measure and use a pencil to mark your cut. Set the depth of the blade to no more than 1/2-inch deeper than the material.

Align the saw at the board's edge, and use a T-square to maintain a perfectly straight cut. Turn the saw on to full speed and push the saw slowly and smoothly along the line.

Jigsaw (Best for Circular Cuts and Outlet Holes)

You can cut curved lines or circular shapes in cement board with a jigsaw fitted with a carbide blade.

Place the board on a sawhorse face-up. Mark the shape of your cut with a pencil. Drill a 3/8-inch hole somewhere along the line with a masonry drill bit. Insert the blade into the hole and bring the saw to full speed. Push the jigsaw slowly and smoothly along the line. You may have to use more than one blade for long cuts since they get dull quickly.

Jigsaws also work well for cutting holes for outlets and switches. Just drill four holes in the corners of the cutout and then use the saw to connect them and punch out the material.

Set the scored sheet over a thin piece of scrap wood, aligning the edge of the wood with the scored line. Apply force to snap the board along the line with your body weight or foot. Use the utility knife to cut any remaining mesh between the two pieces.

If you’re cutting a hole, use a hammer to lightly punch out the hole. Clean up the jagged edges with a utility knife.