What Type of Bricks Are Best for Fireplace Use?

August 4, 2020 Published by Leave your thoughts

Not just any brick is capable of standing up to the long-term exposure to high heat levels and flames found in a fireplace. You need to make sure you’re using bricks that are designed to not crack in such high-pressure environments.

Fireplace bricks, or refractory bricks, have been commercially produced in Brooklyn, NY and elsewhere since the early 1800s, and of course the technology has come a long way since then. These are bricks that are developed with a special mixture referred to as “fire clay,” which features a combination of aluminum oxide, silica and various other materials that give the brick its high heat resistance. This clay mixture, like other types of clays for bricks, then gets baked inside a kiln until it’s hardened and ready for use.

Here’s an overview of what you should know about fire bricks.

Fire bricks offer high temperature resistance

As mentioned above, any bricks used in a high-heat environment must be fire bricks—regular bricks will quickly fail under the high temperatures associated with fireplaces. A failure to use fire bricks in an appropriate application will result in the regular bricks cracking, ebbing away and ultimately collapsing—it’s only a matter of time until this occurs.

Of course, these bricks aren’t just used for home fireplaces—they’re also used for furnaces at a wide range of industrial facilities, in certain types of structures and equipment at steel refineries and even as insulating materials for space shuttles. You can also expect fire bricks to be used for pizza ovens at restaurants, or for large smokers.

In most cases, fire bricks will be a rectangular shape, with a standard size of 9” x 4.5” x 2.5”. This size can vary, though, as fire bricks are easily adapted for various other applications.

There are also different grades of refractory bricks you can purchase in Brooklyn, NY:

  • Low duty: These bricks are generally rated up to a maximum of 1,750 degrees Fahrenheit. They’re most commonly used for fireplace chimneys, and will contain 24 to 26 percent alumina.
  • Medium duty: These bricks are rated for use at up to 2,700 degrees, primarily used for lower-temperature ceramic kilns and backup linings. They contain 34 to 38 percent alumina.
  • High duty: These bricks are rated for use at up to 2,850 degrees, often for boilers, chimneys, kilns and backup linings. They’ll feature 36 to 40 percent alumina.
  • Super duty: These refractory bricks are rated for use at up to 2,900 degrees, though certain applications and atmospheres can reduce this temperature by several hundred degrees. It’s generally used for the same purposes as high duty bricks, and contains 40 to 44 percent alumina.
  • High-fired super duty: These bricks have the highest temperature rating of 3,000 to 3,150 degrees, and are designed to lower the porosity of bricks, increase their physical strength and improve resistance to carbon monoxide disintegration and alkali attacks. They feature 40 to 44 percent alumina.

For more information about fire bricks and their various uses, we encourage you to contact Luisi Building Materials Company, Inc. about the building materials we stock in Brooklyn, NY.

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