How to cut cement board and install it

How to cut cement board and install it

Are you planning on doing your house sidings with cement boards, but aren’t quite sure what tools to use for doing it? Or maybe you need to install a backer board for your brick or floor project?

Installing cement boards can be a fun home project, provided everything goes smoothly. To help with that, here is a short guide on different ways to cut cement boards with different tools and installing them.

How to cut cement backer board

This is quite wide subject, so I’m going to cut it in many parts so you can just scroll to one you need.

How to cut cement board without dust

No one likes dust or jobs that produce dust. If you’re installing cement board inside, even more so as small dust particles get everywhere and spreading plastics and taping them takes forever.

The good thing about flat cement board like backer board is that it can be cut with utility knife like drywall.

Cutting cement board with utility knife

To cut the cement board with utility knife, you need to place it flat somewhere. If you’re working inside it can be on the floor if there is a place or you might have a cutting table set up as we do at bigger projects. No one wants to spend days hopping up and down the floor.

After you have the cement board placed flat. Draw the line you want to cut with a carpenter’s pencil. You can place something to help you cut straight with the utility knife. Press the utility knife to the cement board and drag it towards you, be careful not to slip and hurt yourself.

It’s best if the force you use is mostly toward the cement board and not towards yourself. This way, if the board gives in or the knife slips, it won’t come towards you with force.

After you have done your cut, repeat it few times to get the cut deep enough. Next, you snap it as you would do with the drywall. You lift the other edge up, put your hand or knee behind the scored line and bend it to the side that is not scored. It will snap along the line.

Cutting small details to cement board

Sometimes you need to know how to cut holes in cement board. Cutting fiber cement board with utility knife isn’t always the best option.

You might need to make holes in it or create shapes that can’t be snapped so easily. For that reason, sometimes you need to use some of the following tools.

Cutting cement board with a Dremel and with other rotary tools

Cutting cement board with a Dremel and with other rotary tools

Now Dremels come with many shapes, but what I mean here is the rotary tool that is quite common with DIY hobbyists. If you have one that can do oscillating work, jump forward to the next title.

Small rotary tools can cut cement boards. You put the diamond wheel on it and it can cut it. Another kind of wheel can work, but I like to work stone and cement with diamond. If the wheel is not the right kind and it comes off the shaft it’s attached to, it can be a little bit dangerous to those around as it shoots off.

To cut the cement board, you install the blade and start slowly cutting the line or shape you have drawn. I wouldn’t use this way to do lots of cutting, only small parts and details.

I’d also use vacuum with it to suck the dust straight away.

Cut cement board with oscillating tool

Oscillating tools are another way to do small details to the cement board. It can bide into concrete with a correct blade so it can also work for softer cement board with ease.

Oscillating tools will also make little dust when you cut so it’s good to have vacuum with you.

So to begin, you need to draw your shape to the cement board. After that, you take the oscillating tool, or multi-tool, and put the blade that is recommended for cement materials, and start cutting.

The blade probably has a long cutting edge with teeth. A good way to start is, to begin with, a 45-degree angle so only a few teeth bite into the cement board. After you get the start cut, you level the blade so the rest of the teeth sink into the board. This will even out the workload of the blade.

Cutting cement sheet with jigsaw

Jigsaw is one of the tools again that many DIY hobbyists have. It’s usually a cheap tool and blades come for many different purposes.

Jigsaws have special blades for fiber and plaster and that should work with cement board as well. Both are cement materials.

What’s good about the jigsaw is that it’s easy to work with one hand when you cut the lines. You can also alter the blade speed like with any proper power tool.

To cut with this, you mark your lines and shapes and place the cement board on the table so that you won’t cut anything under it. After that, you make a starting hole with a drill if you’re cutting into the middle of the board or start by the edge if not.

You can vacuum if you have attachment for it

How to cut cement board siding

Cutting sidings is more detailed work than the backer board. It’s the final surface of the wall so the cuts have to be smooth. For that, a masonry blade and table, and circular saw can do the trick with a masonry blade.

Cutting cement board on table saw

Last option here is the good old table saw. There are diamond blades for it as well so you can use it to cut cement board if needed.

This is one option if you want to make fine cuts with the cement board or Hardie plank. It’s good for long straight cuts and cutting straight edges.

If you’re doing sidings with Hardie planks, fine cut details are important. For backer board this might be useless.

Working with a table saw you need to follow common table saw safety. Don’t be putting your fingers near the blade and work safely. Every year many workers get their fingers removed.

How to install cement board

How to install cement backerboard depends on the use. If you install it on floors, you can do it with thinset mortar.

Use a notched trowel to spread the thinset and place the board on top of that. After the thinset and placing of the boards, you need to fasten them to the floor with screws. Get proper screws for the cement board so you won’t have trouble later.

When you are done installing the boards to the floor, you need to do the joints with the mesh tape meant for it. First place some thinset on the joints a little wider than the tape. Then press the tape on top of it and do a thin layer of thinset on top of it. Same method as doing drywall joints.

If you’re doing walls, you can install the cement boards to the studs like you would do with drywall. Just use the special cement board screws for it so they can hold the board properly. You can do the joints the same way you do it on the floor.

If you need to do cement board to drywall transition, you can either create a joint in there or make them level with each other and use joint compound on the joint and sand it level.

How to cut cement board around pipes

If you have pipes on the floor or wall, you need to make holes for them. My go-to strategy is to measure where they are located when you put the backer board into the place, and then drill a hole a little big bigger than the pipe is.

After that, I’ll use a tool like a jigsaw to cut to them in the least amount of distance and the least amount of cuts. So if there are two pipes on the floor, for example, I make 2 holes on the board, and from the outer edge of both circles, I cut to the edge of the board.

After I place the board to the floor, I place the cut piece as well and it will glue there with cement board joint compound. After that I’ll do the joints.

Conclusion

How to cut cement board and install them should be no challenge to you now. It’s not really hard, but you have to take your time doing it.

If you’re doing floors as a beginner, don’t try to make the whole floor at the start. Make boards for half of it, mark the floor area, start spreading the thinset and place the boards.

If you want to do whole floor, that’s no problem either. Just work with manageable amounts and it will be fine. If you need other water resistant solutions, here is how to plaster with cement products.

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