Will Mortar Stick to Fire Bricks?

Fire bricks, also known as refractory bricks, are specially designed bricks that can withstand high temperatures without cracking or crumbling. These bricks are commonly used in the construction of kilns, furnaces, fireplaces, and other high-temperature applications. When it comes to building or repairing structures using fire bricks, one question that often arises is whether regular mortar can be used. Instead, it’s crucial to use refractory mortar, a specialized type of mortar that’s specifically formulated to bond fire bricks together in high-temperature applications.

What Should Fire Bricks Be Laid In?

Fire bricks should always be set in a mortar made specifically for high-temperature applications, known as fire-clay. Fire-clays come in various types, ranging from flint clays to plastic fire clays. These fire clays are composed of natural argillaceous materials, mainly from the Kaolinite group clays, along with fine-grained micas and quartz. In some cases, they may also contain trace amounts of organic matter and sulphur compounds.

Other common mortars such as lime or cement are unsuitable for use with fire bricks due to their lower resistance to heat.

When laying fire bricks, approximately 0.06 cubic meters (75 kg) of fire-clay mortar is needed per 100 bricks. This ensures proper adhesion and stability of the bricks. It’s important to ensure that the mortar joints in the fire-brick lining are as fine as possible. This is done to minimize heat transfer through the joints, ensuring better insulation and heat retention.

With a tighter joint, the fire brick lining becomes more cohesive and less prone to allow the passage of heat or flames through the gaps, ensuring a more secure and reliable fire-resistant structure.

It ensures the bricks longevity and integrity under high-temperature conditions, providing excellent insulation and protection against heat, making it an ideal choice for applications such as fireplaces, kilns, furnaces, and other environments where extreme heat is present.

Using regular mortar for firebrick isn’t recommended as it lacks the necessary refractory properties. Firebricks require specific refractory mortar that can withstand high temperatures and have joints not exceeding 1/8″. However, if the firebrick won’t be exposed to weather conditions, an air set refractory mortar can be used. Although easier to work with, it may take days to fully dry and is water soluble.

Can You Use Regular Mortar for Firebrick?

Using regular mortar for firebrick isn’t recommended. Firebricks should be laid up with refractory mortar, which is specifically formulated to withstand extreme heat.

These types of mortars are generally easier to work with, as they can be applied with a trowel. However, they do require time to fully dry, often taking several days. Additionally, air set refractory mortars are water soluble, so they shouldn’t be exposed to excessive moisture.

They can guide you on the best options based on your specific needs and ensure that you’re using the correct materials to ensure safety and durability.

Instead, refractory mortar, specifically designed for high-heat applications, should be used.

To ensure a secure and solid structure, fire bricks are typically laid using specialized outdoor oven cement. This powerful cement varies from standard masonry mortar and comes in a pre-mixed powder form that only requires water to activate. Prior to placing the first brick, a thin layer of this cement should be applied on the footer for added stability. Now let’s delve into the step-by-step process of laying fire bricks.

What Do You Use to Lay Fire Bricks?

Once the cement is mixed, it provides a strong adhesive that securely bonds the fire bricks together. The thin layer of cement acts as a solid foundation for the bricks to rest on, ensuring stability and strength. Care must be taken to evenly spread the cement and remove any excess to ensure a tidy and secure installation.

Another important tool in laying fire bricks is a trowel. A trowel is a flat, pointed tool with a handle that’s used to spread and shape the cement. It’s essential for achieving a smooth and even layer of cement, ensuring that the bricks are securely in place.

In addition to the trowel, a mallet or hammer may be used to gently tap the bricks into place. The mallet helps to ensure that the bricks are snugly fitted together and eliminates any gaps. It’s important to strike the bricks gently to avoid damaging them or causing them to crack.

It’s important to note that fire bricks can withstand high temperatures and are specifically designed for use in fireplaces, ovens, and other areas where heat is present. They’re resistant to cracking or crumbling under intense heat and offer excellent insulation properties.

Overall, laying fire bricks requires the use of outdoor oven cement, a trowel, and a mallet or hammer. It’s crucial to follow the manufacturers instructions for mixing and applying the cement to ensure proper adhesion. By using the appropriate tools and materials, one can successfully lay fire bricks and create a strong, sturdy structure capable of withstanding high temperatures and providing excellent insulation.

The Benefits of Using Fire Bricks in Construction and Renovation Projects

  • Fire bricks have excellent heat resistance properties
  • They’re more durable compared to regular bricks
  • Fire bricks are ideal for creating fireplaces, chimneys, and pizza ovens
  • They help to retain heat, resulting in more efficient energy usage
  • Fire bricks can withstand extreme temperatures without cracking
  • They provide better insulation and fire protection
  • Using fire bricks reduces the risk of fire-related accidents
  • They’re resistant to harsh chemicals and weathering
  • Fire bricks are environmentally friendly as they’re made from natural materials
  • They’re easy to install and require minimal maintenance

Source: How to Build a Brick Fire Pit? – VITCAS

Watch this video on YouTube:

Therefore, it isn’t recommended to use regular concrete for fire bricks as it may crack and not withstand the intense heat. Instead, using refractory cement specifically designed for high temperatures is the ideal choice for fire pits and other heat-resistant applications.

Can You Use Concrete for Fire Bricks?

This makes refractory cement an ideal material for fire bricks. Fire bricks are designed to withstand extreme heat without cracking or disintegrating, making them essential for applications where heat resistance is crucial. Concrete, on the other hand, isn’t suitable for fire bricks because it lacks the necessary refractory properties.

Fire bricks are often used in fire pits, fireplaces, and wood-burning stoves, where they’re exposed to intense heat. The high temperatures in these applications can cause regular bricks or cement to crack and fail, leading to safety hazards and structural damage.

This insulation property helps to retain heat within the fire pit or fireplace, enhancing the efficiency of heating systems.

It’s thermodynamic properties enable it to withstand extreme heat without expanding or cracking, making it an essential element in creating fire-resistant structures.

When it comes to constructing fireplaces, fire pits, ovens, or other high-temperature structures, using the right type of mortar is crucial. High-Heat Mortar is specifically designed to withstand extreme temperatures, with a maximum tolerance of 2550°F. This durable and easy-to-use mix is ideal for securing fire brick, clay masonry, or as a parge coat.

What Type of Mortar Is Used for Firebrick?

High-Heat Mortar is specifically designed for use with fire bricks and other high-temperature materials in various projects such as fireplaces, fire pits, ovens, and more. This specialized mortar is able to withstand temperatures of up to 2550°F, making it highly suitable for these applications. It’s a high-strength mix that’s also highly workable, allowing for easy and efficient installation.

It’s formulated to have excellent heat resistance properties, protecting the structure from potential damage or degradation caused by intense heat exposure.

It’s specialized formulation and high strength ensure that the bricks stay in place and maintain their structural integrity even during extreme temperature changes.

Alternative Materials for High-Temperature Applications

  • Ceramics
  • Composites
  • Refractory metals
  • Superalloys
  • Carbon/carbon composites
  • Graphene
  • Diamond
  • Thermoelectric materials
  • Copper alloys
  • Advanced polymers


In conclusion, it’s evident that when it comes to constructing a kiln or any high-temperature application that requires fire bricks, special considerations must be made. Traditional mortar isn’t suitable for such conditions, as it can’t withstand the extreme heat. By adhering to these guidelines, one can guarantee that the fire bricks will securely stick and effectively serve their purpose, creating a reliable foundation for any heat-intensive undertaking.

Scroll to Top