When building a pizza oven, the type of bricks you use is one of the most important decisions you’ll make. The bricks need to be able to withstand extremely high temperatures, up to 700°F or more. They also need to retain heat efficiently so the oven can quickly bake pizza. The texture of the bricks affects how well they conduct and radiate heat. Porous bricks with rougher surfaces work best. Here’s an overview of the most common types of bricks used for pizza ovens and the pros and cons of each.
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Firebricks
Firebricks, also known as refractory bricks, are specifically designed for high temperature applications like pizza ovens, kilns, and fireplaces. They are made from fire clay or other refractory materials that can withstand temperatures above 1000°F without cracking or breaking down. The key advantages of firebricks are:
- Withstand very high heat
- Good insulation properties – they retain heat effectively once the oven is hot
- Durable and long-lasting
- Relatively inexpensive compared to other brick types
Firebricks are a very common choice for both homemade and commercially built pizza ovens. They come in a standard 9 x 4.5 x 2.5 inch size in various grades and densities. Denser firebricks hold up better over time but lighter varieties provide better insulation. You can find them at most hardware stores or order them online.
Grades of Firebricks
Firebricks are classified into different grades that indicate their density and heat resistance:
| Grade | Density (lbs/cubic foot) | Maximum Use Temperature |
|---|---|---|
| 23 | 113 | 2760°F (1510°C) |
| 26 | 125 | 3090°F (1700°C) |
| 28 | 131 | 3260°F (1790°C) |
| 30 | 137 | 3470°F (1910°C) |
| 32 | 143 | 3630°F (2000°C) |
| 34 | 149 | 3710°F (2038°C) |
Grade 23 firebricks are suitable for most pizza oven designs. Grades 26 or 28 offer better durability for the oven floor where temperatures are highest. The walls and dome can use the lighter Grade 23 bricks.
Clay Bricks
Standard clay bricks, also called red bricks, are an very affordable option but they have some downsides for pizza ovens. The pros and cons are:
- Pros: Inexpensive and widely available
- Cons: Not designed for high heat so they can crack, spall and deteriorate over time. They also don’t insulate as well as firebricks.
Unprotected clay bricks exposed directly to oven temperatures will break down after repeated heating cycles. However, some builders do use clay bricks as the secondary layer, backing up a single layer of firebricks on the exposed surfaces. This can save on costs while still providing adequate durability.
Cordierite or Ceramic Pizza Stones
Cordierite is a mineral material that is fired into ceramic stones and tiles that have very low thermal expansion. This makes them highly resistant to thermal shock and cracking. Cordierite pizza stones have these advantages:
- Can handle direct flame contact
- Won’t crack with extreme heat fluctuations
- Imparts crispy texture to pizza crust
- Pizza slides off easily
The stones can be used to fully pave the oven floor or just a section of it while the rest uses firebricks. They provide an excellent non-stick baking surface but are more expensive than firebricks. A common brand of ceramic pizza stones is FibraMent.
Castable Refractory Cement
Refractory cement is a specialty high-heat mortar. Some oven builders use it as the primary construction material rather than bricks. The cement is mixed with water, poured into forms, and then cured at high temperatures to set it. The benefits of refractory concrete are:
- Easy to work and pour into any oven design
- Seamless, smooth interior for easier cleaning
- Insulating properties
Castable refractory needs proper curing and drying time to gain full strength. It holds up well when properly set using the manufacturer’s directions. Brands such as Rutland and Fireclay Refractory Cement can withstand over 2000°F in pizza ovens.
Fireclay Bricks
Fireclay bricks are dense, ceramic bricks made from 50% fire clay and 50% regular clay. They are more durable than typical clay bricks but not considered true refractory bricks. Fireclay has these characteristics:
- Withstand temperatures up to 2100°F
- Low porosity makes them stronger but poor insulation
- Heavier than firebricks
- More expensive than regular bricks
Fireclay can work as a lower budget alternative to firebricks. They hold up better than regular clay bricks and provide good thermal mass. However, they may still crack or spall over time if directly exposed to flames. Backing them with a layer of firebricks helps protect them.
Vermiculite Insulation Bricks
Vermiculite insulation bricks consist of vermiculite aggregate held together with a binder. They are manufactured as lightweight, porous bricks optimized for high temperature insulation. Advantages of vermiculite bricks:
- Very good insulation properties – R-value of 2.4 per inch thickness
- Lightweight – 1/3 the weight of firebricks
- Can withstand over 2000°F
- Provides thermal shock protection
- Lower cost than firebricks
Vermiculite bricks are not as durable as firebricks so they require an inner facing of firebricks or other refractory material. They are good for the oven dome and walls but not the floor. Brands such as Stackstone Vermiculite Insulation Bricks are suitable.
Common Pizza Oven Brick Configurations
There are several tried and true methods of arranging the bricks when building a pizza oven:
Firebrick Floor, Fireclay or Firebrick Walls and Dome
Using dense firebricks for the floor lined with additional insulation bricks or material. Surrounding walls use less expensive fireclay or lower grade firebricks. The dome can be fireclay or vermiculite insulation bricks.
Firebricks Floor and Ceiling, Insulation Bricks for Walls
Lining the curved interior ceiling with firebricks protects them from direct exposure to flames. Insulation bricks are used for the walls to reduce heat loss.
Hybrid Firebrick and Cordierite Floor
Covering just the front baking floor area with durable ceramic pizza stones. The rear floor and walls use regular firebricks.
Castable Refractory Oven
Using refractory cement for the entire oven interior. Steel mesh is added to the concrete for strength. Vermiculite or perlite can be mixed into the concrete to improve insulation.
Sourcing Pizza Oven Bricks
Here are some options for buying the types of bricks you’ll need:
Hardware Stores
Many large hardware chains like Home Depot and Lowe’s carry Grade 23 firebricks. They may also stock clay and fireclay bricks. This allows you to hand select the individual bricks.
Masonry Supply Stores
Masonry yards aimed at contractors have a wider selection of firebricks, fireclay and other refractory materials. You may also find cordierite pizza stones here.
Online Retailers
There are many online stores that specialize in firebricks and refractory products. Online purchases often offer lower prices on bulk quantities. You’ll need to pay shipping costs or arrange local pickup.
Some good online sources of pizza oven bricks include:
- Amazon
- Clayplanet
- Global Ceramic Brick
- Pavestone
- ZORO
Brick Size and Quantity
It helps to map out your oven design on paper first. This allows you to determine the brick sizes and how many of each you will need. Some tips when estimating materials:
- Allow for a mortar joint of 1⁄4 to 1⁄2 inch between bricks
- Factor in 10-15% extra for any broken bricks and wastage
- Most firebricks are standard 9 x 4.5 x 2.5 inches
- You may need different thicknesses for the floor, walls and ceiling
- Measure the floor diameter and wall heights precisely
Don’t underestimate how many bricks you need. It’s better to have extras than run short during building. Keep all your receipts to return unopened, surplus boxes.
Types of Mortar for Pizza Oven Bricks
Mortar is used to cement the bricks together into a solid oven structure. There are refractory mortars designed for high temperature use. Regular cement-based mortars will deteriorate. Some good options include:
Fireclay Mortar
Mortar made from fireclay, sand and water. It needs to cure at over 2000°F to gain full strength. Easy to mix yourself using fireclay bricks and sand in 4:1 ratio. Withstands over 3000°F.
High Temp Refractory Mortar
Premixed mortars made specifically for firebrick installation. Withstands temperatures above 3000°F. Brands like Rutland Fire Brick Mortar and Sauereisen Dry Set Mortar work well.
Vermiculite or Perlite Mortar
Mixing vermiculite or perlite insulation into the mortar helps retain heat in the oven. Reduce strength slightly by using more vermiculite and less fireclay.
Castable Refractory Mortar
Some brands of castable refractory also work as mortar for joining firebricks and insulation bricks.
Tips for working with high temperature mortar:
- Mix small batches so it doesn’t set before using
- Work in the shade to prevent premature drying
- Use just enough water so it holds a shape when pressed
- Apply 1/4 to 1/2 inch mortar joints between bricks
- Let mortar cure fully over several days before heating up the oven
Conclusion
Choosing the right combination of brick materials for your pizza oven is important to get proper heat resistance, durability, and insulation. The oven floor experiences the most intense heat and abrasion. Opt for dense firebricks, thermal mass, and possibly cordierite stones in this area.
The walls and ceiling need high temperature rating but lightweight insulation bricks help retain heat and lower fuel consumption. Using different materials zones the oven into areas optimized for their purpose.
Take time sourcing all the oven bricks and refractory materials you will need. Have at least 10-15% extra bricks on hand. Use specialized mortar suitable for the extreme environment inside a pizza oven. With quality materials and proper construction techniques, your homemade pizza oven can provide outstanding service for many years.