What Can I Use Instead Of Firebrick?

What Are Firebricks Used For?

Firebricks have three main uses:

• Lining fireplaces and wood burning stoves – Firebricks are placed inside fireplaces and stoves to protect the surrounding materials from heat damage. The bricks reflect heat back into the firebox, helping improve efficiency.
• Building outdoor brick ovens – Firebricks can withstand very high temperatures, making them ideal for lining pizza ovens, brick barbecues, and other outdoor cooking structures.
• Insulation in industrial furnaces – Firebricks help insulate industrial furnaces, incinerators, and kilns. They prevent heat loss and protect the furnace exterior.

Firebricks are made from refractory ceramics that can withstand temperatures over 2000°F. Their properties make them indispensable for high heat applications where regular bricks would crack or shatter.

Why Seek Alternatives?

Firebricks can be an expensive investment, with traditional firebrick brands costing $5-10 per brick. For large projects like building a wood-fired oven or lining a fireplace, this cost can add up quickly. Some specialty firebrick types, like insulating firebricks, are also not readily available at mainstream hardware stores and may need to be special ordered.

With the rising popularity of DIY projects and alternative home building, many people are looking for cheaper and more accessible substitutes for traditional firebricks. There is a growing interest in using recycled, repurposed, or alternative materials to cut down on costs without sacrificing function. Experimenting with substitutes appeals to the DIY ethic of finding creative solutions using available resources.

Before substituting any material for firebricks, it’s important to understand the desired properties and test any alternatives thoroughly for durability, heat tolerance, and other factors. But with an open mind and some clever thinking, there may be reasonable substitutes for high-cost, hard-to-source firebricks.

Can Regular Bricks Be Used?

Regular bricks, such as standard red clay bricks, can sometimes be used as an alternative to firebricks. However, there are some important considerations:

Pros:

• Readily available and often cheaper than actual firebricks
• Provide reasonable heat resistance if properly prepared

Cons:

• Not designed for high heat like firebricks
• Can crack or explode when heated too quickly
• Lower maximum heat tolerance (around 1,832°F for clay bricks) (DCNZ)

To use regular bricks as firebricks:

• Select solid, dense bricks without holes or cracks
• Introduce heat slowly to condition bricks and prevent damage
• Line interior walls with a layer of refractory mortar for added insulation

With proper preparation, standard bricks can substitute for firebricks in applications up to around 1,500°F. However, for extreme high-heat uses, purpose-made firebricks remain the best choice.

Castable Refractory Cement

Castable refractory cement is a great alternative to traditional firebricks and can withstand extremely high temperatures. According to sciencing.com, refractory concrete is an excellent heat deterrent.

Refractory cement is made of a combination of calcium aluminate cement and fine aggregates. It can withstand temperatures up to 3000°F and is ideal for lining kilns, forges, and furnaces. When mixed with water, refractory cement forms a paste that can be molded into various shapes. It sets into a hard, durable block that is resistant to thermal shock.

One of the key benefits of refractory cement is ease of use. It can be cast into custom shapes and sizes and cures in 24 hours at room temperature. This allows for quick repairs and modifications to existing refractory linings. It also adheres well to firebrick and metals. Compared to firebricks, refractory cement offers more versatility and convenience for high temperature applications.

Insulating Fire Bricks

Insulating fire bricks, also known as soft fire bricks, are made from materials that provide insulation at high temperatures between 2000 – 3200°F. They have lower density and heat conductivity compared to regular firebricks, allowing them to retain heat better.

The key benefits of insulating fire bricks over regular fire bricks include:

• Better insulation – They have a lower thermal conductivity, so retain heat better while allowing the interior of the kiln to reach higher temperatures.
• Higher heat resistance – Insulating firebricks are rated for temperatures up to 3200°F, whereas regular firebricks are typically rated up to 2700-2800°F.
• Lower mass – Insulating fire bricks weigh less than regular firebricks, making them easier to handle and install.
• Lower expansion – The materials used result in less expansion/contraction during heating/cooling cycles.

Good sources for purchasing insulating firebricks include Ceramaterials, SSFBS, and Amazon.

Used Firebricks

Another option is to source used or reclaimed firebricks. These are bricks that have already been used in applications like wood stoves, brick ovens, or industrial furnaces. Many specialty retailers and online marketplaces like Historical Bricks sell used and reclaimed firebricks.

The main advantage of used firebricks is the cost savings versus buying new. However, it’s important to inspect and test any used bricks before using them in a project. Check them visually for any cracks, chips or other damage that could impact performance. Tap the bricks with a hammer to check for soundness, as damaged areas will have a duller sound. You may also want to do a test firing of some sacrificial bricks to ensure they can withstand the temperatures needed for your specific application.

With careful inspection and testing, used firebricks can be a budget-friendly alternative while providing the heat resistance needed for projects like pizza ovens, barbecues, forges and other high-heat applications.

Common Brick Alternatives

While firebricks are specifically designed for high temperature applications, there are some alternatives using readily available materials that can be used instead in certain situations. Three common options are fireclay bricks, magnesite bricks, and silica bricks:

Fireclay bricks are a type of refractory brick that contains alumina and silica. They are formed from fire clay, which is a type of clay that contains aluminium silicate. Fireclay bricks have a high heat tolerance, but not as high as firebricks. They work well in applications up to 2,500°F such as in kilns, furnaces, and fireplaces. Fireclay bricks tend to be more affordable than firebricks.

Magnesite bricks are made of magnesium oxide and carbon. They have excellent resistance to alkaline slags. Magnesite bricks have great thermal shock resistance and insulating properties. They work well in intermediate ranges around 2,000°F such as in cement kilns and calcining furnaces.

Silica bricks are made of silicon dioxide. They have great load carrying strength and volume stability. Silica bricks are resistant to abrasion and corrosion. They work well in hot applications up to 3,000°F such as in glass furnaces, coke ovens, and hot metal ladles.

While not a direct replacement, these common bricks can serve as substitutes in certain high temperature situations where the physical and chemical characteristics match the application. Proper research and precautions should be taken when using alternatives to ensure structural integrity and safety.

Vermiculite and Perlite

Vermiculite and perlite are lightweight insulating materials that can be used to create a fire-resistant insulation when mixed with cement or clay. Both vermiculite and perlite are somewhat porous and contain microscopic air pockets which give them good insulating properties. They are mined minerals that expand and puff up when heated, much like popcorn does.

When mixed with refractory cement, vermiculite and perlite create a heat-resistant insulating material for fireplaces and kilns. A common mixture ratio is 1 part refractory cement mixed with 4 parts vermiculite or perlite. This can be pressed into forms or shaped into bricks and allowed to dry according to the cement manufacturer’s instructions. The porous nature of vermiculite and perlite makes this a lightweight insulating material.

Using vermiculite and perlite alone without cement may provide insulation but will not reach the same high temperatures. For best results, mix with a refractory cement designed for high heat applications. The porous lightweight material helps resist thermal shock and insulate.

Comparing Firebrick Alternatives

When choosing an alternative to firebricks, it’s important to consider the pros, cons, and ideal use cases for each option:

Refractory Cement

Refractory cement is one of the most common firebrick alternatives. It’s made from calcium aluminate and binders that provide strong heat resistance.
Pros of refractory cement include its easy workability for creating custom shapes and ability to withstand temperatures up to 3000°F. However, it can be more expensive than some alternatives and requires precise mixing and curing.

Insulating Fire Bricks

Insulating fire bricks are lightweight and made of refractory ceramics that resist high heat. Pros include good thermal insulation properties and resistance to temperatures above 2000°F. They are less dense than typical firebricks. However, they are more friable and prone to cracking and can be costly.

Used Fire Bricks

Reclaimed fire bricks from old kilns or fireplaces can be an affordable option. The pros are low cost and availability. However, used bricks are less uniform in quality and may have small cracks or damage. They are best for temporary, small-scale purposes where precision is less important.

Sourcing and Budgeting

If you’re looking for affordable alternatives for firebrick, several options are available at home improvement stores and specialty suppliers. For DIY projects, the most convenient and budget-friendly sources are big box stores like Lowe’s and Home Depot.

At Lowe’s, you can find standard bricks for as low as $0.86 per brick. Insulating fire bricks are also available from major brands like Rutland and WHYLW for $2-3 per brick.

Home Depot has a good selection of Rutland firebricks for around $1.25 per brick when purchased in bulk. Their standard brick prices are very similar to Lowe’s.

For used or specialty firebricks, try contacting local steel supply companies, concrete companies, or pottery suppliers. Online stores like Sheffield Pottery also sell new and recycled firebricks at reasonable prices.

The most budget-friendly options are vermiculite and perlite, which can be purchased at garden centers for less than $15 for a large bag. Insulating fire bricks and castable refractory cement also provide very economical alternatives to traditional firebricks.