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Structural Solutions for Fire-Resistant Building

For most builders and architects across the country, incorporating resiliency for their homeowners means selecting building materials that can help withstand the results of severe storms, wind and water. But for others, especially those in fire-prone geographies, fire-resisting properties of building materials is crucial for slowing the spread of fire and sustaining resiliency.

Using LP® FlameBlock® OSB Sheathing for Superior Fire Resistance Ratings

Installing LP® FlameBlock® Fire-Rated Sheathing helps slow the spread of flames. LP FlameBlock panels are structural fire-rated sheathing that combines both fire resistance and structural performance in a single panel. 

To make LP FlameBlock fire-resistive panels, LP’s proprietary non-combustible, fiberglass-reinforced Pyrotite® coating is applied to the OSB panels, combining flame-spread and burn-through resistance.

What Is Fire Resistance in Buildings?

It’s important to clear up any confusion regarding terms such as fireproof, fire resistant and even fire-resistive ratings.

The term "fireproof" is often incorrectly used to mean "non-combustible." Most fire-resistive building products are limited to materials that resist combustion, such as concrete and masonry.

Typically fire resistance refers to the ability of a fire-resistive material to help provide protection for a while. Given enough time, fire could ultimately penetrate or burn through an assembly.

Understanding fire resistance is similar to understanding the differences between a water-resistant watch and a waterproof watch. Water resistance means the watch is impervious to the penetration of water for a period of time. But lose a water-resistant watch to the bottom of a lake, and water will ultimately penetrate the watch's inner workings.

Differences Between One-Sided and Two-Sided Fire-Resistive Materials

The Pyrotite coating on LP FlameBlock sheathing helps give the panels flame-spread resistance. The difference between one-sided and two-sided panels is simply whether the proprietary coating is used on one side or both sides of the panels. But how to choose?

“There’s no choice; you are obligated to use what is required,” says Johnson.

"Two-sided will be used if the assembly requires it or based on the construction type. For instance, an exterior wall in Type III construction requires two-sided regardless of what the assembly says. Our ICC-ES evaluation report ESR 1365 notes where two-sided is required."

The terms “one-sided” and “two-sided” refer to LP FlameBlock panels, which are different from assemblies that are rated one-hour and two-hour. 

As an example, the assembly U348 only requires and is listed with one-sided LP FlameBlock panels. However, when this assembly is used as an exterior wall in Type III construction, two-sided FlameBlock sheathing is required, as noted in ESR 1365.

“Again, type of construction, occupancy group, and fire separation distance will dictate fire-resistant requirements,” says Johnson.

For additional information on fire resistance in building, take a look at fire-resistant roof sheathing and how it can help you approach building better in fire-prone areas.