Concrete Log Siding Adds Low-Level Fire Resistance to Brush Fires
Pyrrothian Lyxterand 
As a building material, concrete is strong, solid, and highly durable, tolerant of much abuse, such as from natural disasters. It can withstand winds beyond 250 miles per hour and resist damage from flying debris in these storms.
When it comes to natural disasters involving fire, including bush or wildfires, concrete can withstand up to four hours of intense heat without other devices like fire sprinklers before it begins to break down.
This makes it superior to materials like steel and wood. Visit Fire Resistance of Concrete Homes| Concrete Construction Magazine – for details on concrete homes’ fire resistance.
Steel-framed houses use exterior cladding with a low fire rating and wooden frames offer a fire rating of merely 45 minutes. Concrete’s unique makeup prevents it from burning or being “set on fire.” When exposed to fire, no molten particles, smoke, or toxic fumes are produced.
Concrete offers the highest level of protection for structures, whether in the process of being built or finished. The material properties allow the least fire risk at a minimal cost and necessitate minimal ongoing maintenance.
Protecting life safety is the fire standard for building regulations; however, concrete exceeds that standard by providing property security. It acts as an extraordinary fire shield, resisting the spread of flames and reducing risks to not only human life but the structure and the surrounding environment.
Concrete Log Siding Fire Resistance
A relatively new concept in house construction is for builders with expertise in concrete to build custom homes using concrete designed to look like wooden logs. Reputable and professional builders show examples on their site. The end result is a property that looks like a log cabin.
The primary difference between this construction and a genuine wooden log cabin is concrete’s exceptional strength, high durability, minimal maintenance requirements, and resistance to physical damage from threats like natural disasters, including fire.
- Wood: Wood is a combustible product. Unless fire retardants are used to treat the material, it can rapidly catch fire, compromising its structural integrity.
- Steel: Steel is not a combustible material, but it does, however, rapidly lose strength when subjected to intense heat, which leads to the potential for a structural failure. When concrete is used to protect steel reinforcements, the thermal barrier maintains a slow heating process.
The material has the best fire rating of other building materials, with the capacity to withstand up to four hours of intense heat.
In fact, in areas devastated by wildfires where property loss was extensive noted, concrete structures were in virtually perfect condition and still standing. Here are different factors that contribute to concrete’s exceptional fire resistance.
Aggregate
Aggregates, which can include siliceous and carbonate, as well as lightweight aggregates, are added to concrete to ensure it meets specific properties required for a building project.
Aggregates are fire-resistant to varying degrees. When subjected to intense heat, carbonate performs best with the highest compressive and tensile strength. Quartz is an aggregate that can decrease resistance considering its thermal expansion differential.
Moisture
Wet concrete can increase spalling due to water’s rapid conversion to steam under extreme temperatures.
Density
The concrete density contributes to a concrete building’s fire density. As a rule, building material with low unit weight has a higher fire resistance. Therefore, dried, lighter-weight concrete structures are superior for fire resistance.
When the material has voids or pores, this can lead to deeper heat penetration and faster degradation.
Thickness
Some people interchange thickness with density when describing construction material properties. These are distinct, with density referring to compactness and volume, while thickness refers more to the material’s dimensions.
The aggregates used play an integral role in the ultimate thickness of the concrete. The thicker the building material, the greater the resistance when subjected to fire.
While concrete is highly fire resistant without added measures, there’s no such thing as being too safe. Read here why concrete is fire resistant. You can boost the material’s resistance in the following ways:
- Supplementary materials: Fire resistance can be improved upon with concrete by adding materials such as slag or fly ash.
- Special additives: The risk of spalling can be reduced with certain additives meant to establish pathways to let the steam escape. This way, there’s less risk of built-up internal pressure.
- Protective coating: Builders can apply specialized fire-resistant coatings to reduce heat penetration and prevent spalling.
While concrete acts superiorly when subjected to heat, it’s not impervious to the effects. Some changes the material can experience with fire exposure include the following:
- Thermal expansion: As is true with many materials, concrete will expand when subjected to heat. The rate for this thermal expansion is low, preventing the fire from rapidly degrading the material.
- Dehydration: Concrete begins to lose inherent moisture when exposed to high heat for a prolonged period.
- Spalling: Spalling is a phenomenon that results in bits of concrete breaking off. This can happen for a number of reasons, particularly if moisture converts to steam.
Final Thought
When building a concrete-sided log cabin, particularly in areas where brush or wildfires are prevalent, contractors will not focus solely on the material’s fire resistance but also factor safety measures in the designs, including active fire protection systems such as sprinklers.
While significant advantages come with using concrete for building homes, emphasizing fire resistance and all safety aspects in the design and construction processes is critical for optimal homeowner well-being.
