The Fire Resistance Advantage of Masonry Materials: Lessons from Recent Disasters

Words: Sam Hoehner
Photos: RCP Block & Brick

As wildfires and structural fires become increasingly prevalent, the resilience of building materials is under scrutiny. Masonry, with its inherent fire-resistant properties, stands out as a reliable choice for construction in fire-prone areas. This article explores the fire resistance of masonry materials, highlighting recent events that underscore their importance.

Masonry materials such as concrete blocks, clay bricks, and natural stones are non-combustible. They do not ignite, burn, or emit toxic fumes when exposed to fire. Concrete masonry units (CMUs) have a high thermal mass that slows heat transfer, providing critical time for evacuation and firefighting efforts.

Masonry assemblies can achieve fire-resistance ratings of two to four hours or more, depending on unit thickness and aggregate type. These ratings are validated through standardized fire testing (ASTM E119) and are documented in building codes like the International Building Code (IBC). The Concrete Masonry & Hardscapes Association (CMHA) provides resources detailing fire resistance ratings for various masonry configurations.

Unlike materials that may weaken or combust under extreme heat, masonry structures often retain their integrity post-fire. This durability minimizes reconstruction needs, reduces insurance costs, and accelerates recovery. In contrast, steel can deform, and wood can char or combust, compromising structural safety.

In January 2025, California faced devastating wildfires that destroyed nearly 17,000 structures and resulted in 30 fatalities. The economic impact is estimated at over $250 billion, making it one of the costliest natural disasters in U.S. history.

Recent incidents have highlighted the vulnerabilities of wood-framed constructions:

A six-story wood-frame rental apartment under construction in Vancouver was destroyed by fire, which also ignited nine smaller fires on nearby properties.
A large lightweight wood-frame hotel under construction in Tennessee was destroyed in a massive fire.

These events underscore the importance of considering fire-resistant materials like masonry in construction, especially in areas prone to wildfire or where large-scale wood-frame buildings are prevalent.

Masonry's fire resistance contributes to long-term sustainability. Structures that withstand fires require fewer resources for repair or rebuilding. Additionally, masonry materials often contain recycled content and are locally sourced, enhancing their environmental profile. Insurance premiums for masonry buildings can also be lower due to reduced fire risk.

From ancient fortresses to modern high-rises, masonry has consistently provided a robust defense against fire. As building codes evolve and the demand for resilient infrastructure grows, masonry's fire-resistant qualities make it a top choice for safe, enduring construction.

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