How To Cut Cement Backer Board

A cement backer board is essential when it comes to DIY tile projects. If you’re a beginner, it can be a little overwhelming working with this new material. 

We have already created some great resources about backer boards for beginners. Start by learning the difference between the two most popular types of backer board – Durock and HardieBacker and then get knowledgeable about how to install these cement boards for your DIY project.

Today we’re focused on a specific step of the installation process – cutting cement backer board. Before you install it and before you cover it with thin-set mortar to install the tile, it is important that you get nice straight cuts.

Although it may feel a little overwhelming, it’s really not that hard to cut backer board – even to get clean cuts. It’s all about having the right tool for the job. 

Of course, there are a lot of different ways you could cut backer board sheets – by using power tools at a high speed, like an angle grinder or a wet saw. But those ways create a lot of unnecessary work and a huge amount of dust. Not to mention, the dust is full of yucky stuff that you shouldn’t be breathing. No thanks to those clouds of thick dust.

So we’re going to show you the easiest method to get accurate cuts on cement backer boards without creating a lot of dust. 

How To Cut Cement Board: Video Tutorial

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How To Cut Cement Backer Board: Step-by-Step Instructions

This how to cut cement backer board tutorial contains affiliate links, but nothing that I wouldn’t recommend wholeheartedly. Read my full disclosure here.

Step 1: Measure and mark

Remember the old adage – measure twice, cut once. To avoid making mistakes, the first thing you should do is double-check all of your measurements before cutting the cement sheets. 

You can make marks on the cement boards with a Sharpie marker or carpenter’s pencil. We prefer a marker because it is easier to see. The gray pencil tends to blend in with the concrete.

Alternatively, as shown in the photo, you can hold your tape measure up to the board and make a small cut with the utility knife as a method of marking it. 

Step 2: Score with a utility knife

The next step is to hold your straight edge (we use a long level) along the straight line you marked on the cement board and grab your cutting tool – we use a utility knife because we always have one handy! They are such a great tool that we use for tons of different things while renovating! But you can also use a carbide-tipped scoring tool that’s made for tile backer boards. 

Use one hand to hold the straight edge along the line and the other hand (your dominant hand) to cut the cement board. You are aiming to just score the top layer/s of the board, not cut all the way through it. There is a thick netting on the inside of the board that will require more passes with the knife. 

A word of caution – even with this method of using a razor knife to cut the board, you’ll inevitably make a bit of dust. So we like to take the boards outside to cut them. Any elevated flat and hard surface will work. We used the bed of the truck this time. If you can’t take them outdoors, be sure to open windows if working in a confined space and wear a mask. 

Step 3: Snap along score line

We use the snap method when cutting cement boards. It’s super easy! 

After one side of the backer board is scored with the knife, you’ll be able to easily bend the sheet along the cut line. 

If it doesn’t bend or snap easily, just run the utility knife in the cut line again to make it deeper. 

Step 4: Run the knife along the cut

For the final step, you can just run the utility knife along the line again to finish the cut, cutting through the netting and cleaning things up. We usually do this from the bottom of the cut as shown in the photo to get a clean cut. Just hold the utility knife on the back side of the board to get this bottom cut.

Once the cut has gone all the way through, remove the other piece of board. If needed, run the utility knife along the cut edge to clean things up if needed. 

But don’t worry about getting it too perfect. Remember that you’ll be mudding and taping the joints, so it is pretty forgiving. 

Cutting cement backer around objects (fixtures and outlets)

If you need to make a hole in the cement backer to fit around objects likes shower fixtures or outlets, here’s the best way to do that: 

• Mark it. Measure carefully and mark the board where you will need the hole. Mark the center of the hole with a cross hatch mark.
• Cut it. Use a carbide-tipped hole saw or a jigsaw with a carbide-grit blade. You may also be able to use Dremel or a multi-tool as well.
• Clean it. If needed, clean up the edge of the cut with a utility knife.
• Check it. Bring it into the space where you are installing the cement board and hold it up (while holding your breath and saying a prayer) to make sure the holes are in the right spot.

Cutting cement backer board doesn’t have to be overwhelming. Just follow this quick and easy step-by-step tutorial to cut it accurately with not much dust.

Once you have everything cut, you’re ready to move on to installing it. Check out this article to learn how to install Durock and HardieBacker board!