How To Cut Cement Board

Two Types Of Cement Board

There are two types of cement board: The first type contains wood fibers or wood particles mixed in with the cement. The second type is portland cement between two sheets of fiberglass mesh. The second type is completely water resistant, and that is what we use in our mosaics when we use cement board.

Two Methods of Cutting Cement Board

There are two methods for cutting cement board: score-then-snap and jigsaw. The score-then-snap is faster and creates less dust, but it can only be used for straight line cuts.


The Score-Then-Snap method uses a box cutter to score the board, with the purpose of the score being to cut the strands of fiberglass mesh on that side of the board. A pencil and straight edge (yardstick or carpenter’s square) is used to measure and mark the board before cutting. Cut slowly and firmly to avoid deviating from the line, which happens all too easily due to the surface roughness and the blade snagging on the mesh. Tip: Cement board dulls blades very quickly, so use an old blade and not a fresh sharp one.

A box cutter is used to score the cement board and cut the fiberglass mesh just under the surface.

Make a second pass in your score to make sure all strands of the fiberglass mesh have been cut. Once that is done, the cement board can be snapped with minimal force using the edge of your work surface. You can also slide a yardstick under the board and line one edge of the yardstick up with the score. Pressing down on both sides should snap the board.

The edge of a worktable or landing makes a natural place to snap the cement board once it has been scored but sometimes all that is required is to slip a yardstick underneath the score and press down on both sides.

The third step is to flip the board over and cut the fiberglass mesh on the back side using the box cutter.


Jigsaws can be used to make curved cuts in cement board, but the process does create silica dust, so wear a dust mask.

Jigsaws should be run at slow speed to minimize the amount of dust generated.

Run the jigsaw at slow speed to minimize the amount of dust you create. Also make sure the cement board is supported and not allowed to flap up and down during the cut. It is possible to damage the board and weaken it by flexing and cracking the concrete.

Of course, the blade in the jigsaw should be a carbide grit blade, which is different from the toothed blades used to cut wood and metal. However, if you are like me, you save and “downcycle” everything, and you can use old wood blades that have become too dull and worn out to cut wood cleanly. The coarser the teeth the better. Run the jigsaw at slow speed and be prepared to change out blades when the teeth get worn off, which happens quickly.

The carbide-grit jigsaw blade is still in the packaging because it will be returned to the store after the photo shoot. We save our old wood blades when they get too dull and worn out to cut wood and use them on the cement board.

How To Cut Holes For Sinks

Sometimes you need to cut holes in cement board, which is commonly done for sinks in countertops. You can use a jigsaw for that, but the problem is how to get the blade started. The solution is to drill a hole in the cement board using a masonry bit. Here are a couple of tips for doing this without damaging the board:

Tip 1. Drill Pilot Hole In Wasted Material

Drill the pilot hole in some of the wasted board to be cut out not right on the line of the cut because you are likely to mess up the smoothness of the sink hole if you try to drill your starter hole there.

Tip 2. Support The Board While Drilling

Make sure the board is supported completely underneath when you drill it and not sticking out over the edge of your work surface. The pressure of drilling is enough to flex and bend the board, which cracks the cement.

When To Use Cement Board As A Mosaic Backer

Indoor mosaic plaques and table tops can be made on plywood, but architectural mosaics such as floors and backsplashes and countertops should be made on cement backer board. The reason is simple: plywood can compress, sag and flex over time, especially when the plywood is part of a house with all that implies about exposure to humidity, water and structural stresses over time.

Most of the building material stores I have used (mostly Home Depot in Georgia) carry the fiberglass mesh variety of cement backer board in two thicknesses: 1/4 inch and 1/2 inch. They say you can use 1/4 inch in flooring because the concrete backer board doesn’t supply any structural strength to the floor, but I’ve noticed that the edges of 1/4 inch board tends to get damaged more easily during handling and construction, especially if the tile doesn’t get laid right away. That being said, you might need to use 1/4 inch on your floor merely to save weight.

An Important Note About Weight

When installing tile floors, make sure you have a carpenter look at the joists under the floor to make sure it can hold the weight of the backer and the mosaic tile.







14 responses to “How To Cut Cement Board”

  1. […] my previous article about how to cut cement board for use as a mosaic backer, I explained how I didn’t buy carbide-grit jigsaw blades for this because I re-used my […]

  2. Briar Avatar

    Hi there,

    Where do you buy the cement board, do you have the product name? Thanks in advance, B

    1. Joe Moorman Avatar
      Joe Moorman

      Cement backer board or tile backer board is a commodity like 2x4s sold at building material stores. The Hardiboard product has brand name recognition and includes wood fibers I think, but I haven’t used it as much as the regular cement board.

      I hope this helps,

  3. ims bolt Avatar

    I really like your methods of cutting cement board. You described two methods for cutting cement boards but I like “Score then Snap” method the most.

  4. Marti Hand Avatar
    Marti Hand

    Very descriptive…thank you.

  5. Loren Avatar

    I need an 18” round concrete backer board for a patio table that i want to create a mosaic on top. I don’t have any of the cutting tools you mentioned. Do you have any suggestions on where i might purchase a round board, where i could get a square/rectangular piece cut into a circle or another suggestion for a foundation for my outdoor mosaic?

    1. Joe Moorman Avatar
      Joe Moorman

      Before I got my power tools, I would always ask friends if they or their partner had what I needed. You might be able to get them to cut it for you. You could also make a round board this way:

      1. Loren Brown Avatar
        Loren Brown

        Thank you for the response and the information.

  6. Rebecca Avatar

    When using concrete backer board as the sole surface of a mosaic what do you suggest I do about the edges? Should I just cover it with a thin layer of thin set mortar or should I find tiles small enough to fit the 1/2in all around? All the images I’ve seen on here never show the details of the edges.

    1. Joe Moorman Avatar
      Joe Moorman

      Hi Rebecca,

      How edges are treated depends on where and how the mosaic is installed. I have used thinset mortar to plaster the edges of concrete board to strengthen them and make them less crumbly. For dry indoor mosaics, you can make frames from wooden molding or re-purposed picture frames. I don’t like the idea of tiling edges that are subject to impact. It is only a matter of time before the mosaic is damaged.

      I really need to update old content on the website so that it suggests foam-core tile backer board in place of concrete backer board for non-step surfaces. When I started the Mosaic Art Supply, I hadn’t yet made peace with the idea of using foam-core tile backer board for archival reasons, but I have come around, especially if the mosaic needs to be shipped or relocated. The weight saving of using the foam-core boards is significant, and most heavy objects being moved that get damaged are damaged because of their weight.

      Brand names of foam-core backer board include Durock, Schluter Kerdi Board, Laticrete Hydroban Board, Johns Manville GoBoard, and Wedi Board.


  7. Lisa A Scheevel Avatar
    Lisa A Scheevel

    Can the foam core backer board be used Outdoors?

    1. Natalija Moss Avatar
      Natalija Moss

      It can be as long as you’re careful to seal the edges. Kerdi has a product they sell for use with their Kerdi-Board called Kerdi-band. In the marble restoration write-up linked below you can see a picture of the edge of the board wrapped with Kerdi-Band.

  8. Meg LaVergne Avatar
    Meg LaVergne

    I have a piece that I created on a cement backer board. I want to attach something to the back of it to hang it outside on a fence or wall. I thought of using wire or leather or rope. I had previously glued some wood slats to the back of the piece and then used heavy duty staples to attach the wire. The glue has not held up (maybe I used the wrong kind). I wasn’t sure how to go about attaching something to the back of the board. Any suggestions would be helpful.

    1. Joe Moorman Avatar
      Joe Moorman

      I have used thinset to attach two 4-inch tiles to the back of my backer. Underneath the tiles were the ends of the loop of wire I used to hand the mosaic.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.