Fire clay brick for superior fire resistance

Legend tells us that Mrs. O’Leary’s cow knocked over a lantern in the barn on the evening of October 8, 1871, igniting the Great Chicago Fire that destroyed 3.3 square miles, killed 300 people and left another 100,000 homeless. Only a handful of structures in the path of the fire survived, and those that did were almost exclusively of masonry construction.  

One of the most significant legacies of the fire, besides the O’Leary family being unceasingly (and probably wrongly) blamed, is the abundance of brick structures built to replace those that were lost and to prevent another catastrophic fire in the future. The City of Chicago eventually banned wood construction, and other cities, such as Denver, Colorado, followed suit with their own “insist on brick” policies after their historic fires.

While brick walls are not the only ones that can satisfy the minimum fire resistance ratings mandated by today’s building codes, designers and developers are beginning to demand more than simply “good enough” when it comes to fire safety. The dramatic videos of wildfire destroying homes, businesses and landmarks in the western U.S. has them asking, “How do we design for a future in which wildfire and extreme weather threats are the norm?”

Great responsibility

Designers and builders of commercial, office and multi-family structures carry a heavy responsibility on behalf of the public. Their structures must protect large numbers of people who had little to say about the design and construction of the buildings they occupy. And, these buildings often exist in high densities and in close proximity to each other, meaning design and construction choices impact more than just a single owner of a single property. Fire resistant structures not only minimize damage while firefighters are responding and give occupants more time to evacuate, they also slow the spread of fire from and to neighboring buildings. Even Firefighters think so. The designer’s responsibility doesn’t end with protecting the structure’s occupants or the owner’s investment, either. There is still the challenge of doing great design work that pleases the client, contributes to the neighborhood and effectively expresses the designer’s vision. A bunker may be safe, but it’s not likely to be beautiful.

The whole package

But brick…brick is beautiful. With endless color, texture, size and bond pattern combinations, there is no other material with greater design flexibility. And, brick comes with superior fire resistance built right in. In fact, a simple single-wythe, solid brick wall of four inches with no additional components provides over two hours of fire resistance all by itself. Most other wall assemblies require a combination of layered materials to achieve the fire ratings mandated by building codes, and they still don’t approach the bar set by brick. 

Combine brick with a few other components in time-tested wall assemblies, and you have lots of options for satisfying your budget and design goals without sacrificing top-notch fire protection. Here are some examples: 

  • Brick/Concrete Masonry, Load bearing = 4hrs
  • Brick Veneer/Wood Stud, Load bearing = 4hrs
  • Brick Veneer/Steel Stud, Load bearing = 1hr
  • Thin Brick Veneer/Steel Stud (with fiberglass batt and gypsum board) = 1hr

Note that brick’s inherent fire resistance comes in lighter packages, too. Thin brick and hollow brick veneers deliver serious fire resistance with less mass. In one independent study comparing hollow brick veneer, fiber cement board and vinyl siding, only the brick assembly withstood a fire test for more than an hour. Vinyl siding failed after less than 20 minutes. 

Multiple-threat defender

In many parts of the country, fire is only an occasional threat while severe storms are frequent. Brick meets these threats with the same beauty, design flexibility and durability, shunning windblown debris that easily damages — and violently penetrates — the facade materials of occupied buildings.

In a study that launched wood studs at brick, fiber cement and vinyl siding wall assemblies, only the brick wall was able to turn back the 2×4 traveling at over 50 miles per hour with no damage. Watch the video. If you think that’s unrealistic, check out the aftermath of this storm that rolled through the Midwest in 2020.

Responsibility comes into play here again for designers and builders of structures in the public realm. When the evening news is playing post-storm footage on an endless loop, your design can be the tattered, damaged, barely recognizable building that people fled, or the refuge that people fled to.

What do you want your design legacy to be?

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