How to Cut Firebrick

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Anyone who has used them knows just how helpful firebricks can be. They are built to withstand more heat than traditional bricks, making them perfect for a fireplace or fire pit.

However, they sometimes need to be adjusted or trimmed in order to be used to the best of their abilities. But is it possible to cut firebricks at home with basic tools?

What You Will Need

To cut fire bricks, you will need to have a few items to make the procedure work with total ease. Thankfully, most of the tools needed are ones that you likely already have laying around the house.

In fact, this is a task you could probably tackle within just a few hours. It does take some time and effort and energy, but it is the best way to make your firebricks perfectly fit in any pit or fireplace.

  • Firebricks: Of course if you are going to be cutting fire bricks, you actually need a good amount of them to choose from. It is always smart to buy more than you think you might need, in case you make a mistake and have to start over again. It is better to have too many than too few.
  • Hammer and Masonry Chisel: You likely have these items in your tool box, although if you don’t have a chisel, you should purchase one because they are used often in many DIY home projects.
  • Mitre Saw: There is a good chance you do not own a mitre saw and that is understandable. It is the sort of heavy machinery that a lot of homeowners don’t have. That being said, this isn’t a necessary tool because we will outline a way to cut fire bricks with or without a saw. Yet, if you do have a saw like this, it is probably the easiest and fastest way to cut your brick.
  • Safety Goggles, Long Sleeves, Gloves: Safety is always the most important part of any construction project, including cutting fire bricks. The goggles are mandatory because you have no idea if any small pieces of brick could fling back when the cut is being made. The long sleeves are needed for the same reason because small pieces of brick could do damage to your skin. As for the gloves, not only will they protect your hands but they will also provide you with a more secure grip of the bricks and tools.
  • Chalk: While a sharpie pen might also work when making marks on your firebrick, a chalk is best because it is guaranteed to work on any sort of brick material and it will wash off in time. A sharpie marking will remain for a long time and is unsightly.

Learn how to drill into brick in our in-depth guide!

How to Cut Firebrick

There are two most popular ways to cut firebrick, one that needs a chisel and hammer and the other that needs a mitre saw. We are going to showcase the hammer and chisel method first. You will see that there are some steps repeated in both approaches.

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Where the two paths diverge is when you start actually making cuts into the brick. Before that, the steps are identical but it’s definitely important you follow them closely no matter which approach you take.

Using Hammer and Chisel

  1. Measure the Brick Against the Space. Before you can get anything done, you need to know the amount of space you have to work with. If you are inserting the firebrick into a spot on a fireplace, you need to measure the brick against that open space. From there, you will decide how much brick needs to be cut. For example, if your brick is nine inches and you measure the space at 6 inches, you know that you need to slice three inches off of the brick. Measuring the space you will be using is essential when making the right cut.
  2. Use the Chalk to Draw a Cut Line. With your chalk, you need to perfectly measure the amount of brick you will be cutting and create a legible and thick mark with the chalk, so you know where your cut line is. This is the exact spot you will be cutting.
  3. Grab the Hammer and Chisel. It is time to get your tools ready. Make sure your safety equipment is on and then grab your hammer and chisel and get ready to do some cutting.
  4. Place the Brick on a Sturdy Surface. You want the brick to lay at about hip-height, that is the right spot to hammer at and will prevent much strain in your back or arms. Make sure that whatever surface the brick is laying on is steady and will not shake or, worse yet, shift when hammering.
  5. Hold the Chisel Along the Mark. Place the head of the chisel straight along the chalk mark and prepare to start hammering. Wrap your hand firmly around the chisel’s handle and keep your arm parallel to the brick. Do not squeeze too hard but do not hold too loosely either.
  6. Tap the Chisel with the Hammer. Many people want to slam the hammer down on the chisel when they start cutting the brick. This is not the right approach. Instead, you want to tap gently and repeatedly. After a few blows, you will see you are making progress and will continue to keep tapping to get further through the brick. Once you have made a lot of headway on one side of the firebrick, turn it over and start on the other side, then the other, then the other. This way you will be creating universal progress on all sides of the brick.
  7. Break the Brick. When you have cut through the brick almost to its core, you want to line up the hammer with the loose side of it and bring the hammer down on the top of the chisel. It should break off the large chunk of brick you are getting rid of. If you have been cutting evenly across all four sides of the brick, this final hit of the hammer shouldn’t have to be that strong.

Following these steps will result in the brick cut to fit the space needed to fill. It is very important that your cuts are accurate so remember to have a firm grip on the chisel and be sure that you have made accurate measurements and markings with your chalk.

Learn how to cut brick pavers while you’re at it!

Person using a miter saw

Using the Mitre Saw

As mentioned, you can also cut firebrick by using one of the best mitre saws. If you have this saw, then this method will save you some time.

The steps you follow when cutting a firebrick with a mitre saw are identical to the steps you follow with a hammer and chisel. You still measure the brick against the space you will be filling, along with marking it with the chalk.

However, there are some key differences:

  • For one, you need to soak the brick in water for 2 minutes before making your cuts. This ensures that you will reduce the amount of brick dust.
  • After soaking them, let them drain them for 5 minutes and let all of the water get out.

Once you’ve finished soaking and draining, follow these steps for cutting:

  1. Set up your saw with a masonry and make sure you are using the correct angle. It should be easy to set the right angle for the cut you are looking for.
  2. Align the brick on the saw table with the chalk marking set up against the cut line of the blade. It is vital that the chalk marking is literally right below the blade.
  3. Press the blade downward – it should easily slice through the brick. Make sure to keep your hand steady and the rate of you lowering the blade also consistent.

You may need to repeat the process multiple times to make a solid, thorough cut but you should find that this process is easier than using a hammer and chisel because it doesn’t require as much physical strain and takes less time.

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Spruce up your outdoor space by attaching a window box to brick (without drilling).

In Conclusion

A firebrick is a wonderful tool for any home and can make a fireplace or fire pit so much better and stronger. They really are a great way to add a lot of functionality to some of the best parts of your home. But they can be tricky too and sometimes need to be adjusted so they can fit in your home as you need them to. That is when you will need to cut a firebrick.

Although the process might take time and effort and energy, its benefits far outweigh the work you will put in. In no time at all, your firebrick will be custom cut and able to fit into even the tightest spaces. Your fireplace or fire pit will finally be complete and ready to be enjoyed by family, friends, and all of your house guests

An expert at home repair, remodel, and DIY projects for nearly 40 years. His first experience came in completely restoring an antique home. Completely redone from the inside out, and restored to its original form, the home is a featured design by renowned Southern California Architect Cliff May, considered to be the father of the California Ranch Home. Now Dennis spends his time on fine woodworking projects and tool comparisons.