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LP FlameBlock Fire Rated SmartGuard Treated OSB

LP® FlameBlock® Fire-Rated SmartGuard Treated OSB Sheathing offers you the best of both worlds—impressive structural strength and remarkable burn-through fire resistance. Created by applying a patented, non-combustible Pyrotite® coating to LP® OSB panels, LP FlameBlock Sheathing is an ICC certified (ESR-1365), structural fire-rated sheathing with a Class A Flame Spread Rating. It provides extended burn-through resistance, delivering a 20-minute thermal barrier (ASTM E119). It’s durable on the job site, easy to work with, and is Exposure-1 rated to withstand weather during normal construction delays. LP FlameBlock Sheathing is cost competitive and is available in a variety of PS2-rated thicknesses and lengths, including Struc-1. Plus it contains no hazardous chemicals. Backed by a 20-Year Transferable Limited Warranty.


  • Structural Fire-Rated Sheathing
  • UL-Certified Class A Flame Spread Rating
  • Non-Combustible, Fiberglass-Reinforced Magnesium Oxide Coating over LP OSB
  • Available with Pyrotite Coating on One or Two Sides of the Product
  • Exposure 1 Classification, Durable and Easy to Handle Job Site
  • No Hazardous Chemicals
  • Variety of Thickness Categories and Lengths, Including Struc-1
  • ICC Approved for Wall and Rood Deck Applications
  • CAL FIRE Code-Approved for Exterior Walls, Eaves and Soffits in WUI Zones
  • Available in 7/16, 15/32, 19/32, 23/32 Categories
  • 20-Year Transferable Warranty