LP FlameBlock

For Code Officials

Engineered For Code Compliance

LP® FlameBlock® Fire-Rated OSB Sheathing is a component of code-compliant fire-rated wall assemblies and roof deck applications. It installs easily like regular OSB, without extra components.

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Code Approved

  • ICC-certified (ESR-1365)
  • Class A and 30-Minute Flame Spread Rating (ASTM E84, UL723)
  • Combines flame-spread resistance and burn-through resistance
  • 15-Minute Thermal Barrier Protection (UBC 26-2)
  • Component of fire-rated interior and exterior wall assemblies and roof decks

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Exposure 1 Weather Resistance

LP® FlameBlock® carries the Exposure 1 classification which certifies that it's able to withstand normal exposure to moisture during construction. Interior-grade FRT plywood must be protected from precipitation during construction.

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Technical Support And Education

LP provides easy access to any code approval reports and technical documents you need, including installation detail drawings and ESR reports.


Certification and Testing

  • Certification ICC-certified (ESR-1365) as a code-compliant component of fire-rated wall assemblies and roof deck applications
  • Class A and 30-Minute Flame Spread Rating (ASTM E84, UL723)
  • Meets 15-Minute Thermal Barrier requirements (UBC 26-2)
  • CALFIRE/OSFM code-approved (CBC Chapter 7A) for use in exterior walls, eaves and soffits in California WUI Zones

Relevant Listings/Assemblies

  • 2-hour Load-Bearing Fire-Rated Exterior Walls:
    • UL Listing BXUV.U349
    • UL Listing BXUV.W408
    • UL Listing BXUV.W408 Extended
  • 1-hour Load-Bearing Fire-Rated Exterior Walls:
    • Intertek Listing LPB/WPPS-60-01
    • UL Listing BXUV.U348
    • UL Listing BXUV.V311 
  • 2-hour Load-Bearing Fire-Rated Interior Walls:
    • UL Listing BXUV.U350
  • Roof Decking Application to satisfy vertical continuity requirements for fire walls

Weather Resistance

  • Exposure 1 Classification – Certified to withstand normal exposure to moisture during construction delays


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