Can I Use A Normal Brick Instead Of Firebrick?

What is Firebrick

Firebrick, also known as refractory brick, is a specially engineered brick made for applications involving high temperatures, such as lining furnaces, fireplaces, and chimneys. It has high thermal stability and resists damage from repeated heating and cooling cycles.

The key properties of firebrick that make it suitable for high heat applications include:

• High refractoriness – Firebricks have a high melting point, typically 1580–1760°C, allowing them to withstand extremely high temperatures without deforming or melting.
• Low thermal conductivity – Firebricks are poor conductors of heat, helping retain heat in furnaces and fireplaces.
• Resistance to thermal shock – Firebricks resist damage from rapid temperature changes, allowing repeated heating and cooling.
• High strength – Firebricks maintain mechanical strength and low creep at high temperatures.

Firebricks are typically made from refractory clays or other refractory aggregates. Common materials include alumina, silica, magnesite, and combinations of these. The raw materials are formed into brick shape and fired at high temperatures up to 1800°C to create a strong, durable brick.

According to research, firebricks have a porosity between 22-45%, compressive strength above 10 MPa, and refractoriness above 1580°C (Saidi, 2016). These properties allow firebricks to withstand the demanding conditions inside furnaces, boilers, fireplaces, and other high temperature equipment.

What is Normal Brick

Normal brick, also known as clay brick, is one of the most common types of brick used in masonry construction Wikipedia. It is made from clay that is molded, dried, and fired in a kiln. Normal bricks are durable, fire-resistant, and weather-resistant building materials that can last hundreds of years.

Normal bricks have compressive strengths around 1,500 psi, making them suitable for load-bearing walls, foundations, and other structural elements Glen-Gery. They are commonly used in homes, commercial buildings, landscaping, and paving projects. Normal bricks can be laid in many patterns to create decorative and structural bonds.

Common uses for normal bricks in construction include building exterior and interior walls, chimneys, walkways, patios, retaining walls, and other masonry structures. Their modular size, durability, and aesthetic qualities make them one of the most versatile building materials.

Key Differences

Firebricks and normal bricks differ quite significantly in their material composition and properties. According to Behzi, firebricks are made from refractory ceramic materials that can withstand extremely high temperatures ranging from 1000°C to 1800°C. Normal bricks on the other hand are typically made from clays or shale materials and have a much lower heat tolerance around 1000°C.

Firebricks are designed to have very low porosity, meaning they retain heat and resist thermal shock cracking. Normal bricks are comparatively more porous. The composition and porous nature of normal bricks makes them prone to cracking and deteriorating when subjected to high heat according to Haloong.

Using Normal Brick in High Heat

While it may seem convenient to use normal bricks for high-heat applications like fireplaces, pizza ovens, grills, etc., there are significant risks with doing so that should be strongly considered. Normal brick is simply not engineered to withstand continuous high heat like firebrick is.

The clay mixture and firing process used for standard bricks makes them prone to cracking, breaking down, and crumbling when exposed to the intense heat present in fireplaces, ovens, etc. According to Chicago Tuckpointing and Masonry, the likelihood of cracking is very high, which can lead to damage over time as the bricks slowly disintegrate.

Firebrick is designed specifically to withstand temperatures up to 2000°F or more. Normal brick starts to crack at much lower temperatures, sometimes as low as 250°F based on the specific composition and firing method used. Exposing normal brick to the 1000°F+ temperatures inside a fireplace or pizza oven will almost certainly cause damage fairly quickly.

Per eHow, firebrick contains special compounds that prevent cracking and deterioration. Using normal bricks lacking these compounds is not recommended for any high heat application. The likelihood of needing frequent repairs or full replacement is very high.

Modifying Normal Brick

There are some ways to try to improve the heat resistance of normal bricks, but they come with limitations and cautions. Applying high-temperature coatings like refractory cements or rigidizer can provide some added protection according to this video. However, these coatings may not stand up to prolonged, direct high heat. Normal bricks, even with coatings, lack the dense microstructure of true firebricks, making them more prone to cracking under thermal stress.

Another option is to wrap the bricks in kaowool ceramic fiber blanket. However, this is only a temporary fix, as the kaowool will degrade over time, requiring replacement. While coatings and wraps may buy some time, they do not truly convert a normal brick into a firebrick. For applications like forges or pizza ovens with sustained high heat, properly sourced and manufactured firebricks remain the recommended material according to experts.

Sourcing Firebrick

Firebrick can be purchased from most major hardware stores, home improvement stores, and online retailers. Some of the most common places to buy firebrick include:

• Home Depot
• Lowe’s
• Menards
• Amazon
• eBay

Firebrick is sold individually or in packs. A single firebrick generally costs $1-$5 depending on brand and specifications. Buying in larger quantities can reduce the per-brick cost. A pallet of firebrick containing about 500 bricks may cost $300-$800.

Be sure to check the specifications of any firebrick you purchase. High quality firebrick should be rated for temperatures up to at least 2,000°F. Some important specifications to verify are the temperature rating, density, and compression strength.

For specialty refractory projects, you may need to order from a refractory supplier. They will offer more selection in terms of brick sizes and temperature ratings over 3,000°F.

When Normal Brick May Work

In certain lower heat applications, normal brick may sometimes be acceptable to use instead of firebrick. According to Brickhunter, clay bricks can withstand temperatures up to around 650°C before starting to break down. So for low-temperature wood-fired pizza ovens that don’t exceed this temperature, clay bricks may potentially work.

For outdoor brick fire pits that generate moderate levels of heat, normal bricks are again sometimes used, although firebricks are still preferable. According to Holy Smoke, firebricks are able to withstand hotter temperatures without cracking or breaking down. But for more casual backyard fire pits, the heat may not be extreme enough to justify the added cost of firebricks.

In general, firebricks are still strongly recommended for any high-heat application like forges, kilns, and high-temperature ovens. But for certain limited lower temperature uses, normal clay bricks may potentially work, especially if cost is a main concern. However, their structural integrity may degrade over time with exposure to heat.

Safety Considerations

When using normal bricks in high heat applications, there are some important safety considerations to keep in mind. Exposing normal bricks to prolonged high heat can lead to cracking, flaking, and deterioration over time. As the bricks break down, this can release toxic gases and create a fire hazard.

According to experts, when normal bricks are heated, they can off-gas a number of dangerous compounds like carbon monoxide, sulfur dioxide, and volatile organic compounds (VOCs). These toxic gases can be very hazardous if inhaled. Additionally, as the bricks deteriorate, pieces can break off and spread embers or sparks which increases the risk of fire.

It’s recommended to always use proper firebricks rated for the intended temperature in any high heat application like fireplaces, ovens, or kilns. However, if you do use normal bricks, be sure to frequently inspect them for any cracking or deterioration. Also ensure the area has proper ventilation to avoid buildup of dangerous gases. Consider using a gas detector as well. Take safety precautions like wearing a respirator and having a fire extinguisher on hand. Be prepared to replace any bricks that show signs of breakdown.

Exposing yourself or your home to the dangers of deteriorating bricks is not recommended. While normal bricks may withstand lower heats temporarily, for prolonged exposure at high temperatures, firebricks are the safest option.

Expert Recommendations

Professional masons and contractors who build fireplaces, ovens, and other high-heat structures strongly recommend using real firebrick rather than regular brick whenever possible (Source: https://www.brickwoodovens.com/pages/fire-brick). Firebrick is engineered to withstand repeated heating and cooling cycles up to 2000°F, while regular brick starts to decompose at lower temperatures. Trying to cut costs by using regular brick in places that require firebrick often leads to cracks, crumbling, and deterioration over time.

Masonry experts advise to only use firebrick for the inner lining and firebox area of high-heat structures. Regular brick may be acceptable for the outer non-heat-exposed portions, but it still carries more risk of damage than real firebrick. For optimal safety and durability, firebrick is strongly recommended wherever heat exposure will occur (Source: https://englishsweep.com/whats-the-difference-between-common-brick-firebrick/).

In summary, masonry professionals caution against substituting regular brick for firebrick in any high-heat application. The potential cost savings often lead to much greater expenses down the road from having to repeatedly rebuild and repair damaged structures. For best results, only use firebrick in areas that will be exposed to heat, especially the firebox and chimney liner.

Conclusion

In summary, there are several key differences between firebrick and normal brick that make firebrick the recommended choice for high heat applications. Firebrick is designed to withstand extremely high temperatures, up to 3000°F in some cases, without cracking or breaking down. It has a much lower rate of heat transfer, meaning it insulates better and helps retain heat in furnaces and fireplaces. Normal brick simply cannot withstand the intense heat and rapid temperature changes that firebrick can.

While it may be tempting to try substituting normal brick to save money, this is not advisable in any structure meant for high temperatures. Normal brick can crack, explode, or crumble, posing serious risks to both property and safety. For optimal performance and safety, firebrick remains the standard recommendation from experts for lining furnaces, fireplaces, kilns, and other high temperature applications. If sourcing firebrick is an issue, specialists may be able to suggest alternatives that provide adequate insulation and heat resistance. But normal brick is generally not a good solution.

In summary, when high heat is involved, firebrick is specially engineered for the job. It simply outperforms normal brick in terms of insulation, durability and ability to withstand intense heat and temperature changes. For critical high temperature applications, firebrick remains the sensible choice to protect your project and promote safety.