Building on the legacy of DensDeck® Prime Roof Board, Georgia-Pacific sets the new standard for performance with DensDeck StormX Prime Roof Board.

DensDeck StormX Prime Roof Board stands up to extreme weather and tough new hail standards to give your commercial roof the top defense. Featuring enhanced strength and moisture resistance, this premium cover board is FM classified for Very Severe Hail (VSH) in approved single-ply assemblies.

Fire Resistance

Non-Combustible Gypsum Core

  • 0 flame and smoke spread when tested in accordance with ASTM E84 and CAN/ULC-S102.
  • UL Classified for resistance to external fire sources [per ANSI/UL 790 and CAN/ULC-S114].
  • UL Classified for resistance to fires below roof [per ANSI/UL 1256].

Wind Resistance

Board Strength and Mat to Core Bond

  • Improves roof’s ability to resist wind.
  • Increases membrane bond strength compared to paper-faced insulation or no cover board.
  • Improves fastener pull through performance compared to paper-faced insulation or no cover board.

Puncture Resistance

Rigid Board Protection for Membrane and Insulation

  • Resists impact from repeated events such as maintenance foot traffic.
  • Helps relieve static pressure caused by the weight of rooftop equipment.
  • Helps defend against dynamic impact from flying debris.

Hail Resistance

Strength of gypsum core with fiberglass mat reinforcement

  • Stands strong against repeated hail strikes.
  • DensDeck® StormX™ Prime Roof Board was the first gypsum cover board FM classified for VSH in approved single-ply assemblies.¹

*Please consult ASTM E136 and ASTM E84 for information concerning the test methods and measures for combustibility and flame spread. For information concerning the UL 790 and UL 1256 classifications for DensDeck® Roof Boards, consult the applicable UL certifications directory.  Please note, however, that the performance of a roof depends on all components used in the roofing assembly and how the components interact.  Passing a fire test in a controlled laboratory setting does not mean that a particular product or system will necessarily provide the same resistance or protection in an actual fire.

¹Consult RoofNav for FM-approved and VSH assemblies with DensDeck® prime and DensDeck® StormX™ Prime Roof Boards.

Enhanced Strength

+ Next-Level Storm Defense for your Roof Assembly.

The increased board density and reinforced glass mat significantly improves wind uplift and impact resistance.

*Consult RoofNav for VSH assemblies with DensDeck StormX Prime Roof Board.


Data That Speaks to Durability

Enhancing the durability and puncture resistance of the DensDeck® Roof Board offerings for FM Global Very Severe Hail (VSH) rating specifications, DensDeck® StormX™ Prime Roof Board assemblies meets these rigid standards for impact resistance, using engineering ingenuity to help reduce roof assembly storm damage risk.

FM Global tests roof systems for moderate and severe hail impact resistance on how the withstand dropping a 2-inch diameter 1.19-pound steel ball from either 81 inches or 141.5 inches, respectively. This results in impact energies of 8 ft-lbs for moderate hail (1.75″ or bigger) and 14 ft-lbs for severe hail (2″ or bigger). The new VSH designation uses an ice launcher to propel a 2-inch diameter laboratory-made ice ball at 152 to 160 feet per second. This applies impact energy of 53 to 58 foot-pounds on the surface of the tested sample–an increase of almost 4x compared to severe hail. Learn more about FM’s VSH impact-resistance classification here.

DensDeck StormX Prime Roof Board Stands Strong

As weather events intensify, your roof assembly must adapt too. DensDeck® StormX™ Prime Roof Board helps commercial rooftops hold tough under extreme weather conditions with enhanced moisture and impact resistance.

How to Install DensDeck StormX Prime Roof Board

Learn how to properly store, handle and install DensDeck StormX Prime Roof Board. This video shares best practices for laying the board to strengthen your roof assembly.


Get all the detailed technical information you need to know about DensDeck® StormX™ Prime Roof Board. You can explore the limited warranty, submittal and installation guide.

DensDeck® StormX Prime Roof Board Limited Warranty

DensDeck® Stormx Prime Roof Board Submittal

DensDeck® Stormx Prime Roof Board install Guide

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