What Architects Need to Know About the Latest LP® FlameBlock® OSB Evaluated Assemblies

Finding the proper fire-resistance-rated OSB assembly that meets code compliance and a building’s structural requirements can be tricky. This is true especially in today’s building environment when architects are asked not only to maximize space and building performance but overall cost-effectiveness as well. 

LP® FlameBlock® Fire-Rated Sheathing combines flame-spread resistance and burn-through resistance in a single versatile OSB panel. It’s ICC-evaluated to meet code requirements for fire-resistant construction as a component of two-hour rated LP FlameBlock assemblies, one-hour rated assemblies, and roof deck applications. LP FlameBlock sheathing may allow fire-resistance-rated walls to be assembled faster than common alternatives, reducing labor costs while providing exceptional strength, durability and consistency.

Meeting Local Codes Using 2-Hour or 1-Hour Fire-Rated Exterior Wall Assembly With OSB

As codes change and construction practices evolve, LP works to advance new LP FlameBlock wall assemblies to UL and Intertek for evaluation. “We recognize opportunities to expand our assemblies and applications,” says Scott Johnson, Construction Services Manager for LP Building Solutions. “When new building codes are adopted, we go to UL and Intertek––as well as other entities––so we can get wall assemblies evaluated to fit the criteria for your project.”

And while many architects may be familiar with what could be referred to as LP FlameBlock sheathing’s core 8 evaluated fire-resistance-rated wall assemblies, it’s important to know there are many, many more versatile sheathing assemblies and options listed under both UL and Intertek. This is especially important when you are searching for, as an example, two-hour or one-hour fire-rated exterior wall assemblies with OSB.

Finding the Proper Fire-Rated OSB Assemblies for Your Project

“We have more solutions for increased fire-resistance performance,” says Johnson. “For example, the U349 is typically shown with wood studs. But it has also been evaluated with metal studs. The U349 with brick can provide two-hour resistance from either side and may eliminate the need for exterior gypsum.”

 The UL-listed V337 assembly with stucco does not require exterior gypsum and is a two-hour resistance from either side. 

“One of the true benefits of LP FlameBlock wall assemblies is that it can reduce the amount of exterior gypsum on a project. Sometimes they can eliminate the need for exterior gypsum altogether,” says Johnson.

LP FlameBlock UL and Intertek Wall Assembly Solutions

LP is always looking at ways its assemblies can be used as practical solutions. For example, LP now has assemblies listed by Intertek that demonstrate the continuity of the fire resistance from the foundation to the roof deck for townhouse separations. “We now have a complete system that shows details for the floor to wall interface and the roof trusses,” says Johnson. “This is a great system and offers five different solutions. 

From tall and skinny urban construction to single-family townhouse-style homes, many urban housing developments present challenges to maximize fire protection and minimize construction timelines.

“For single family construction with minimal separation, like 12 inches, the LP FlameBlock V340 assembly is a good fit,” says Johnson. “It eliminates the gypsum in the air gap and is a single sheet solution on either side of the stud wall, which helps you more easily coordinate your trades.” 

Check out another example of how LP FlameBlock sheathing met the specific needs of an architect. In this case study Dwight Miller, Associate Principal at Lantz-Boggio Architects, required wall assemblies that provided a consistent plane across both one-hour and two-hour fire-rated wall assemblies.

Additionally, a newly established wall assembly, the V340, may be used in Type V construction fire walls when designed and constructed in accordance to National Fire Protection Agency (NFPA) 221. These single sheet solutions allow for smooth sequencing and facilitates construction. 

Advice for Finding Versatile OSB Solutions

“Many architects are accustomed to looking online for versatile OSB sheathing, but I recommend going ‘old school’—pick up the phone and call us,” Johnson advises. He is a licensed engineer and has decades of real-world experience under his belt. “I’m here as a free consultant. My goal is to help you choose the most efficient assembly to give you the best results.”

Call LP at 615-610-1540 to be connected with a building solutions expert. To learn more about fire-resistance technology, read more about the science behind LP FlameBlock OSB.