For about a century, architects and builders have used gypsum panels in wall assemblies to meet the criteria for 1- and 2-hour fire-resistance-rated wall assemblies. As product engineering develops, more and more architects are now looking for product solutions that bring added value to their 1-hour and 2-hour fire-resistance-rated wall assemblies.
Many are specifying LP® FlameBlock® Fire-Rated Sheathing because it meets code requirements for fire-resistant construction while potentially providing faster and easier installation than assemblies that use exterior gypsum and structural panels. They can also provide added design flexibility by reducing the overall wall thickness.
With these design challenges in mind, LP Building Solutions created LP® FlameBlock® Fire-Rated Sheathing for low- and mid-rise wood and light gauge structures. LP FlameBlock sheathing may allow fire-resistance-rated walls to be constructed faster than common alternatives, potentially reducing labor costs while providing exceptional strength, durability and consistency.
UL fire-resistance-rated wall assemblies with LP FlameBlock sheathing provide several benefits to architects, engineers, builders, developers, contractors and even homeowners. LP FlameBlock sheathing wall assemblies provide design flexibility by combining structural capacity and fire resistance in a single panel. It may eliminate a layer of gypsum to help simplify and expedite the construction process. Potential cost savings may allow designers and builders to redirect the funds into design elements their clients are seeking, increasing the value of the property.
Let’s examine how LP FlameBlock sheathing can be used in a few different fire-resistance-rated wall assemblies.
These UL assemblies are commonly used for single-family homes within close proximity of a property line.
UL Design No. V340: This assembly allows for 2x4 wall construction and is fire-resistance-rated for 1 hour from both sides.
UL Design No. U348 (stucco): This assembly is used with stucco and is fire-resistance-rated for 1 hour from both sides.
UL Design No. U348 (brick): This assembly is used with brick and is fire-resistance-rated for 1 hour from both sides.
These assemblies are typically used in dividing walls in townhouses.
UL Design No. V340 (Two 1-hour walls, back-to-back)
UL Design No. U350A and U350B (Common 2-hour fire-resistance-rated wall)
UL Design U348: This is commonly used in Type V multifamily construction in load-bearing exterior walls. It also allows for the use of fiberglass insulation. This assembly is fire-resistance-rated for 1 hour from the interior side only, except when brick and stucco is the exterior facing.
These assemblies are commonly used for Type III and Type V exterior walls.
UL Design No. V337 (1-hour from either side)
UL Design No. V337 (2-hour interior, 1-hour exterior)
UL Design No. V340 (1-hour from either side)
UL Design No. V340 (2-hour interior, 1-hour exterior)
When using UL Design No. V340 assemblies for Type III exterior walls, 2-sided LP FlameBlock sheathing is required.
UL Design No. V337 with gypsum and V337 with stucco (2-hour from either side)
UL Design No. U349 (2-hour interior)
UL Design No. U349 (2-hour interior, 1-hour exterior)
UL Design No. U349 (2-hour from either side)
Code compliance does not have to limit design flexibility, budget or schedule. LP FlameBlock Fire-Rated Sheathing assemblies offer code-compliant solutions for a variety of building needs, including numerous UL assemblies for fire-resistance-rated wall systems. The OSB substrate of LP FlameBlock sheathing also has an Exposure 1 classification—which signifies that panels are intended to resist the effects of moisture on structural performance during active construction.
Fire-resistance-rated wall assemblies shouldn’t interfere with your design capabilities and construction schedules. Check out our LP FlameBlock page to learn more about the various assemblies.
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