Fire Bricks: What Are They And When Do You Use Them?

by Joost Nusselder | Last Updated:  June 4, 2022

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Whether building your very own wood-fired oven or just keeping the heat even in your smoker, you’ll need to get the SPECIAL kind of bricks called “fire bricks.” But what are they? And WHEN do you use them?

Fire bricks are made of ceramic and used to line ovens to protect against high temperatures and harsh conditions. They can withstand much higher temperatures and provide better insulation than normal bricks because of the compressive strength of 200 to 220 Kg/cm2 and their 5 to 10% water absorption.

In this article, I’ll look closely at fire bricks and when you need to use them.

What are fire bricks

The Benefits of Fire Bricks


If you’re looking for a way to keep your home toasty in the winter and cool in the summer, fire bricks are your best bet! Not only do they provide great insulation, but they’re also more durable than regular bricks. So you don’t have to worry about them cracking or crumbling due to extreme temperatures or improper storage.


Fire bricks come in all shapes and sizes, so you can find the perfect fit for your project. Plus, they’re lightweight, so they won’t add too much bulk to your construction.


Fire bricks are made to last! They’re more rigid than regular bricks, so they can withstand the elements without breaking down. Plus, they’re incredibly lightweight, so you don’t have to worry about them weighing down your structure.

The Basics of Fire Bricks

What are Fire Bricks?

Fire bricks are a special type of brick designed to withstand high temperatures. They’re usually yellowish-white or white in color and come in different sizes, ranging from 9 X 4.5 X 2.5 inches to 9 X 2.75 X 2.25 inches. One of these bad boys weighs about 30 to 35 N.

What Makes Fire Bricks So Special?

Fire bricks are pretty special because they have a few unique properties that make them ideal for high-temperature applications. Here’s a quick rundown of their special features:

  • Compressive strength: 200 to 220 Kg/cm2
  • Water absorption: 5 to 10%
  • Good chemical resistance

Where Can I Use Fire Bricks?

Fire bricks are often used in ovens, furnaces, fireplaces, and other places where heat is a factor. They’re also great for lining the walls of a fireplace or furnace to protect them from the intense heat. So if you’re looking for a brick that can handle the heat, fire bricks are the way to go!

Everything You Need to Know About Fire Clay

What is Fire Clay?

Fire clay is a special type of clay that can withstand high temperatures and is used to make fire bricks. It’s made up of two main components – silica and alumina – with silica ranging from 60 to 70% and alumina ranging from 25 to 35%. It also contains other elements like calcium, magnesium, iron, potassium and titanium, but these make up less than 5% of the total composition.

Types of Fire Clay

Fire clay can be divided into three categories based on its heat resistance:

  • High: Can withstand temperatures between 1482 and 1648°C
  • Medium: Can withstand temperatures between 1315 and 1482°C
  • Low: Can withstand temperatures up to 870°C

Where to Find Fire Clay

Fire clay is usually found beneath coal seams, so if you’re looking for some, you know where to start digging!

What Kind of Fire Bricks are Out There?

Acidic Fire Bricks

These bad boys are made to resist the acidic actions of chemicals or weather. Natural fire clay is usually enough to do the job, but if you need extra protection, silica is added to the mix. To hold it all together, a bit of lime is thrown in. Acidic fire bricks are cooked at high temperatures for a long time.

Basic Fire Bricks

These are great for resisting corrosion and chemicals. Magnesia is the main ingredient, with lime as the binding material. Different types of basic fire bricks include:

  • Magnesite bricks
  • Magnesia-carbon
  • Magnesia-chrome bricks

Neutral Fire Bricks

These are the chameleons of the fire brick world, offering protection from both acidic fumes and corrosive actions. There are two types:

  • High alumina bricks – these contain a lot of alumina
  • Chromite bricks – these are made up of chromium, iron oxide, silica, bauxite, and iron ore

So, if you’re looking for a fire brick that can do it all, neutral fire bricks are your best bet!

What are Fire Bricks and What are They Used For?

Inner Surface Lining of Kilns, Furnaces, and Chimneys

Fire bricks are the perfect material for lining the insides of kilns, furnaces, and chimneys. They provide a protective layer that helps reduce damage from fire accidents. Plus, they have a lower thermal conductivity, so they make great insulators.

Wood-Fired Ovens

When it comes to wood-fired ovens, fire bricks are the way to go. They provide the perfect inner lining to keep your oven safe and sound.

Insulating Material for Furnaces and Ovens

Fire bricks are also great for insulating furnaces and ovens. They help keep the heat in and the cold out, so your food will be cooked to perfection every time. Plus, they’re super durable, so you don’t have to worry about replacing them anytime soon.

What Are Fire Bricks and What Are Their Drawbacks?

The Weighty Issue

Concrete fire bricks are made of a much heavier material than other masonry components, which can really weigh down a project – both literally and figuratively. This means you’ll be shelling out more cash for your construction project.

Noise Pollution

Clay bricks don’t have many air holes, so they don’t do a great job of keeping sound out. So if you’re looking for a quiet space, fire bricks probably aren’t the best choice.

Not So Eco-Friendly

Fire bricks are made with soil, which isn’t the most environmentally friendly material. So if you’re looking to go green, you might want to look elsewhere.

Everything You Need to Know About Fire Bricks

What are Fire Bricks?

Fire bricks, also known as refractory bricks or kiln bricks, are made of a special ceramic material that can withstand extreme temperatures. This makes them ideal for use in kiln firings, where temperatures can reach up to 2000°F!

Can I Use Regular Bricks Instead?

Nope! Regular bricks won’t stand a chance against such high temperatures and will likely crack and break. So, if you’re looking to fire up your kiln, you’ll need to make sure you’re using fire bricks.

Any Other Tips?

Here are a few pointers to keep in mind when using fire bricks:

  • Make sure to check the temperature rating of the fire brick before using it.
  • Fire bricks should be placed in a single layer, with no overlapping.
  • Fire bricks should be spaced evenly to ensure even heat distribution.
  • Fire bricks should be inspected regularly for any signs of damage.
  • Always wear safety gear when handling fire bricks.


Fire bricks are a MUST for any oven project that requires insulation and durability, I think that’s obvious now you’ve read about their property and uses.

I hope you’ve learned everything you needed to start using them for your own builds.

Joost Nusselder, the founder of Lakeside Smokers is a content marketer, dad and loves trying out new food with BBQ Smoking (& Japanese food!) at the heart of his passion, and together with his team he's been creating in-depth blog articles since 2016 to help loyal readers with recipes and cooking tips.