Brett Drury

Some interesting myths about the science of perimeter fire containment have developed over the years. Some may be understandable, others not so much. See if any of these project misconceptions are familiar to you:

Myth #1
The building has a sprinkler, fire detection, and alarm system. It’s a safe building.
A balanced safety strategy always includes three components: detection, suppression (active), and compartmentation (passive). This strategy recognizes the essential role of redundancy and a tested passive solution. Smart life safety design assumes active system failure at the worst possible moment. Passive compartmentation protects occupants when all else has failed.

Myth #2
The perimeter fire barrier system complies with code. It’s a safe building.
Maybe, maybe not. The International Building Code 2015 Sections 705.8.5, 715.4, 715.5, and 715.4.1 detail mixed, potentially confusing instructions about exterior curtainwall protection. One perimeter fire containment expert has worked hard over the years to clear up the confusion.
Angie Ogino, technical services leader at Owens Corning, a manufacturer of perimeter fire control systems, understands why architects and code officials may be puzzled: “There are actually two sections in the 2015 IBC that relates to the exterior curtainwall. The truth is they don’t synch-up well.” Which leads to …

Myth #3
I specified mineral wool safing insulation in the interior joint just like code says. It’s a safe building.
Ogino and veteran code officials know better. Fire testing demonstrates you can’t just put safing insulation next to the glass cladding or other exterior façade components, in spite of what code may imply. “The glass is going to break and fall away very early in the fire, leaving a perfect opening for the flames to leapfrog up the exterior of the structure,” Ogino explains. “An exception in section 715.4 is when the vision glass of the non-rated exterior wall assembly extends to where the window sill transom becomes in line with top surface of the fire-resistant floor assembly. Although the code allows for approved materials per ASTM E119, this approach is not the safest. It is recommended that a system tested to achieve ASTM E2307 compliance should include protection of the spandrel wall and the combination of the safing insulation within the interior joint.”

Myth #4
I’ve specified mineral wool safing insulation up against a wall that has been insulated with a spray foam solution at the interior joint. It’s a safe building.
The flash point of spray polyurethane foam (SPF) is 392 F. Some SPFs can be treated with halogenated fire retardants. However the fire retardant only delays flash point while giving off toxic fumes in high heat. The retardant also weakens over time. Ogino suggests a perimeter fire system that includes mineral wool that resists fire and temperature up to 2,000 F and does not require harmful chemical additives to achieve fire resistant properties. Mineral wool insulation is naturally fire resistant since it is manufactured from slag and rock.

Myth #5
SAFETY Act Designation isn’t a big deal. It’s a safe building.
SAFETY Act Designation by the U.S. Department of Homeland Security is a big deal for owners looking to safeguard their investment and for architects looking to enhance their reputation. Any product and service that carries the SAFETY Act Designation indemnifies the owner and designer from liability in the event of a terrorist act on the structure. Today only one building material product, Thermafiber mineral wool insulation from Owens Corning, has earned the SAFETY Act Designation.

Myth #6
Aesthetic intent and energy conservation are the top priorities. It’s a safe building.
Placing the central focus on life safety does not mean sacrificing architectural integrity. Just ask the owners and designers behind the Salesforce Tower, Wilshire Grand, the Steinway Tower, 1 World Trade Center, Via 57 West, or dozens of other notable properties worldwide. Owens Corning Thermafiber mineral wool insulation offers a high level of fire performance without compromising R value. Thermafiber mineral wool has an R value of up to 4.3 per inch.

It’s time to set the myths aside. Focus on occupant safety by observing best practice in perimeter fire containment.

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