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UL Fire Ratings for Wall Assemblies Explained

Finding the proper code-compliant fire-rated wall assembly for wood frame construction is a challenge. That challenge grows even more complicated depending on the project's size and scale. Navigating UL fire rated assemblies and Intertek listings can also add a layer of complication.

In today's building environment it is key for architects, engineers and specifiers to maximize space while maintaining the cost effectiveness of the building's construction and design. Additionally, AEC professionals must fully understand and comply with all fire protection guidelines applicable for mid-, low- and high-rise structures.

LP® FlameBlock® Fire-Rated Sheathing, Intertek Listings and UL Fire Resistance Ratings


With these design challenges in mind, LP Building Solutions created LP® FlameBlock® Fire-Rated Sheathing for low- and mid-rise wood and steel-framed structures. LP FlameBlock sheathing allows fire-rated walls to be assembled faster than common alternatives, reducing labor costs while providing exceptional strength, durability and consistency. Additionally, LP FlameBlock panels offer Exposure 1 classification to withstand normal exposure to moisture during construction.

These UL fire-rated assemblies for walls, as well as Intertek-rated wall assemblies, provide benefits to architects, engineers, builders, developers, contractors and even homeowners. LP FlameBlock sheathing wall assemblies can reduce the number of components within a wall, increasing the flexibility of the design. The cost savings allow designers and builders to redirect the funds into design elements their clients are seeking, increasing the value of the property.

2 Hour UL Fire-Rated Wall Assemblies:

UL Design No. U349 (2-hour wall; fire-rated from inside)

Application:

  • Commonly used in Type III load-bearing exterior walls

Benefits:

  • Reduces dead load and wall thickness versus common alternatives
  • Reduces labor costs and construction time
  • Provides better substrate for securely fastening exterior facing
  • Allows fiberglass insulation

u349-design

 

UL Design No. W408 (2-hour wall; fire-rated for 2 hours inside, 1 hour outside)

Application:

  • Commonly used in Type III load-bearing exterior walls close to property line

Benefits:

  • Reduces dead load and wall thickness versus common alternatives
  • Reduces labor costs and construction time
  • Fiberglass insulation can be used when standard brick is exterior facing
  • Provides better substrate for securely fastening exterior facing

design-408

U350 UL Fire-Rated Assemblies for Double Walls:

UL Design No. U350 (Type A) (2-Hour Partition Wall; fire-rated on both sides)

Application:

  • Commonly used in load-bearing partition walls in multifamily construction, including townhomes

Benefits:

  • Labor/material cost savings and reduction in dead load due to elimination of a layer of gypsum (vs. WP3820)
  • Cost-effective, space-saving alternative to area separation fire walls using shaft liner (where code-compliant)
  • Sound Transmission Class (STC) rating of 62

u350-type-a

UL Design No. U350 (Type B) (2-Hour Partition Wall; fire-rated on both sides)

Application:

  • Commonly used in load-bearing partition walls in multifamily construction, including townhomes

Benefits:

  • Labor/material cost savings and reduction in dead load due to elimination of a layer of gypsum (vs. WP3820)
  • Cost-effective, space-saving alternative to area separation fire walls using shaft liner (vs. UL375)
  • Sound Transmission Class (STC) rating of 62

u350-type-b

Intertek One Hour-Rated Wall Assemblies:

Intertek Listing LPB/WPPS-60-01 (1-hour wall; fire-rated from both sides)

Application:

  • Commonly used in 1-hour exterior walls along property line, including single-family construction 

Benefits:

  • Reduces dead load and wall thickness versus common alternatives 
  • Reduces labor costs and construction time
  • Provides better substrate for securely fastening exterior facing

One-Hour Rated UL Wall Assemblies

UL Design No. V311 (FlameBlock Plus 1-Hour wall; rated on both sides)

Application:

  • Intended for use in 1-hour exterior walls along property line, including single-family construction

Benefits:

  • Reduces dead load and wall thickness versus common alternatives
  • Reduces labor costs and construction time
  • Provides better substrate for securely fastening exterior facing
  • Allows brick, stucco, steel and fiber cement exterior facings

design-u311 

UL Design No. U348 (1-hour wall, Fire-rated from inside only)

Application:

  • Commonly used in Type V load-bearing exterior walls 

Benefits:

  • Reduces dead load and wall thickness versus common alternatives
  • Better substrate for securely fastening exterior facing
  • Allows fiberglass insulation
  • Provides better substrate for securely fastening exterior facing

design-u348

 

Fire 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 plenty of assemblies listed by Intertek as well as listings by UL for fire-rated wall systems.

Check out the LP FlameBlock page to learn more about these fire-rated wall assemblies.