Fire Brick / Firebrick / Refractory Brick - The Basic Building Block of Pizza Ovens

Q: So what is Fire Brick and how is it different from a standard clay brick or concrete brick?

A: Fire Brick (also known as Refractory Brick) is a block of ceramic material that contains 50%-70% Aluminum Oxide and is designed to not only withstand temperatures up to 3000° - but to also retain the heat for maximum energy efficiency and low fuel consumption. In other words – It’s a special type of brick that can get really, really hot… hold that heat, and then redistribute that heat over a long period of time in a process that we like to call “baking”.

There are several types of firebrick on the market - Low Duty, Medium Duty, High Duty, Insulating Firebrick and Red Clay Firebrick.

HARD FIRE BRICK - It is HIGHLY RECOMMENDED to use a LOW or MEDIUM DUTY Firebrick for your BrickWood Box. HIGH DUTY is a good firebrick, but does not insulate as well as Low or Medium Duty.

● Low Duty (2100°F)
● Medium Duty (2500°F)
● High Duty (2800°F)
● Super Duty (3200°F)

INSULATING FIREBRICK (Soft, IFB) - is great at retaining heat, but it’s a very soft / lightweight firebrick and can easily be cracked and chipped – not the best firebrick to use for a wood-fired BBQ that will last 300+ years.

● IFB2300 - 2300°F Insulating Firebrick
● IFB2600 - 2600°F Insulating Firebrick
● IFB2800 - 2800°F Insulating Firebrick
● IFB3000 - 3000°F Insulating Firebrick


BEWARE! The RED CLAY FIREBRICK (aka – the cheap “firebrick” at the Big Box hardware stores). This is just a basic clay brick that is used to line firepits in your backyard. It is NOT, NOT, NOT the type of firebrick you want to use in your BrickWood Box – put it back on the shelf and briskly walk away!

PLEASE NOTE: All BrickWood Oven and the BrickWood Box are designed to use the world’s most common fire brick size: 9” x 4.5” x 2.5”. Since there are SO MANY different sizes and types of fire brick on the market, BrickWood Ovens DOES NOT offer support or offer guidance on how to build a BrickWood Box using any other size fire brick. If you use any brick size other than 9” x 4.5” x 2.5”, you will need to do the math calculations and pattern layout to see your brick will work.

Find a FIRE BRICK DEALER near you!

While the majority of your masonry materials can be found at your local Big Box hardware store (Lowes, Home Depot, Menards, Rona), be sure to visit your local Landscape & Masonry Supply Stores first! Not only are you supporting local businesses, but most Landscape & Masonry supply stores stock those hard-to-find items that the Box Box stores just don’t carry. Items like Fire Brick, Fireclay, Lime, Stucco, etc… all the components necessary to build a pizza oven while on a budget. Prices on fire brick at your local landscape supply are usually LOWER than fire brick purchased directly from the manufacturer ($2.50 avg. per fire brick).

Want professional-grade refractory materials for your pizza oven project? How about a “just add water” high-temp mortar that is rated to 2800° vs. mixing / making high-temp mortar with silica sand, fire clay, portland cement & lime? Then you need to purchase your refractory materials from a manufacturer like HarbisonWalker International ($4.25 avg. per fire brick). With over 30+ HarbisonWalker locations, there’s a good chance you live in (or near) a city with a HarbisonWalker distribution center. If pallet pick-up is not an option, most HarbisonWalker locations can schedule local / regional freight delivery for your order to your home or jobsite. Here are some money-saving Freight / Pallet Delivery Options if you choose pallet delivery.

If you can’t find Fire Brick Splits – Or if you are cheap and just want to save a few bucks and make your own…

Use your Sharpie to mark a line down the middle of (18) Full Size Fire Brick (9” x 4.5” x 2.5”) then use your Angle Grinder with Masonry Blade to cut each brick in half. This process will give you (36) Fire Brick that are 9” x 4.5” x 1.25” in size. While cutting the brick adds an hour to your construction time, it will save you $30 or more in Fire Brick costs!

Q: Why do Fire Brick Splits cost the same as Full Size when they are exactly 1/2 the size using 1/2 the material?

A: Full Size Fire Bricks outsell Splits 20:1 – but the costs of the brick molds are the same… which is usually $30K - $40K per mold. Manufacturers have to recoup some of the costs of that expensive mold (which is run far less) by charging more for the splits. It’s a Supply & Demand thing…

Hi, and happy Independence Day.
Thanks for the response.

I don’t get you’re comment about a weekend user.
Are you implying that the Portland and vermiculite hold up Better than
The unglazed firebrick .
The base obviously can be poured to incorporate any size insulation brick or vermiculite pour.
I have 8 boxes of these bricks and would like to incorporate them in

Hi Christopher,

I think by “weekend user” you can substitute “light user” (not cranking out 30 pizzas a night and keeping the fire going through the next day for other bakes).

The comparison with fiberboard is that these insulating bricks will have properties similar to fiberboard. It will work but not provide as much R value as the Perlite/Portland cement type cast insulating floor. You can definitely use them, but you might find your slab sucking more heat out of the floor of your oven.

Hope this helps!

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