So what is Fire Brick and how is it different from a standard clay brick or concrete brick? Well… 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
Finally… 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.
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…