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How DensDeck® Roof Boards can help you build a more durable low-slope roof than HD ISO.

Physical Properties of DensDeck® Roof Boards vs. high-density polyisocyanurate (HD ISO) when used as a cover board as of January 2024.

From dropped tools during installations to the risk of fire and storm damage, the more resilient your roofing systems are, the fewer problems they’ll cause you—and all project stakeholders. Building your reputation for installing top-of-the-line roofs starts with recommending the right materials.

You probably already know that not all Class-A roofing assemblies are equal. But you might not realize what an impact the differences can have when it comes to fire, puncture, and wind uplift resistance. That’s why it helps to see all the ways DensDeck® Roof Boards outperform less robust options like HD ISO.

Increased Strength

DensDeck® Roof Boards have 8- to 11-times greater compressive strength than HD ISO when it’s used as a cover board. The higher flexural strength of DensDeck® Roof Boards can also increase flute-span capability while guarding against maintenance traffic and insulation compression. Both benefits can help guard against punctures and extend the life of your commercial roof.

The U.S. solar industry is expected to triple by 2028, giving building owners even more to consider when it comes to adequate rooftop support. DensDeck® Roof Boards act as a rigid substrate for weighty rooftop equipment like solar panels and HVAC units, mitigating the risk of foot traffic, punctures and fire.

Building owners can also avoid the costly removal and reinstallation of solar panels during re-roof jobs if a roof and its solar array have a similar lifespan. The strength of DensDeck® Roof Boards can help owners get the most out of their commercial roof.

DensDeck® Roof Boards and HD ISO in a third-party burning brand test.

Fire Resistance

It’s also important to think about increased fire risk due to the electricity produced from rooftop solar installations. Since fire can spread so quickly from one building to another, it’s smart to choose materials with fire resistance.

DensDeck® Roof Boards are noncombustible based on ASTM E136. Their gypsum core and fiberglass mat facers help to mitigate the risk of rooftop fire damage from every direction. HD ISO is combustible. It will smolder and burn under certain conditions.

Ready for the Weather

One of the most unpredictable risks to roofing systems is the increase in severe weather events across the country. DensDeck® Roof Boards can help protect against wind uplift during rough weather because they offer enhanced strength, a rigid base of support and a strong mat-to-core bond. They also help guard against membrane delamination and fastener withdrawal. HD ISO’s lightweight foam can’t provide the same level of flexural strength and wind uplift resistance.

For even more protection against extreme weather, DensDeck® StormX™ Prime Roof Board is FM classified for Very Severe Hail (VSH) in approved single-ply assemblies. HD ISO is not approved for VSH.

Watch comparison videos of the two cover boards at buildgp.com/densdeck/risky.


1 https://www.polyiso.org/page/500SeriesHDCoverBoards

2 https://www.seia.org/research-resources/solar-market-insight-report-q2-2023#:~:text=Over%20the%20course%20of%20our,of%20year%2Dend%202022