Roofing Systems

Enhancing commercial roof performance with DEXcell Cement Roof Board

Oct 2, 2023

Discover how the versatility of DEXcell makes it suitable for nearly every roof system


If you’ve ever found yourself working on the roof of a large commercial building project, you know all too well how exposed you and your crew are to the elements. From severe heat to frigid lows and gusting winds, Mother Nature has no sympathy for your goal of getting the day’s tasks done. So, when it comes to selecting what products to use, it makes sense to choose the ones that are easier to handle and faster to install.

That’s where DEXcell® Cement Roof Board — a lightweight, moisture- and mold-resistant roofing panel — stands apart from the competition, making it the ideal substrate board, thermal barrier and coverboard for commercial roofing applications. Plus, it adds a layer of resiliency to the building to combat long-term weather impacts.

DEXcell Cement Roof Board, which is exclusively provided by National Gypsum Company, features:

  • An exceptionally hard, durable surface that is designed to withstand prolonged exposure to moisture
  • Excellent bond/pull-through/uplift values
  • A Portland cement and lightweight aggregate core with heavy-duty fiberglass-mesh facers
  • A FM Class 1/UL Class A fire-rating

DEXcell’s high-performance elements combine to create a board optimally suited for a wide variety of roofing systems, including fully adhered, mechanically attached and ballasted roofs using single-ply membranes; modified bitumen; fluid-applied; built-up; spray foam; and metal.

“When used as a coverboard in roofing assemblies, DEXcell Cement Roof Board offers both protection and support for the roof membrane above the board and the insulation below the cement board. In addition to being moisture and mold resistant, it also provides increased fire resistance and reduces the potential for penetration damage to the membrane."

Tony Fuller


Tony Fuller

Director, Technical & Product DevelopmentPermaBASE Building Products

DEXcell Cement Roof Board helps installers beat the heat in Arizona

See how DEXcell’s installation benefits and product performance give commercial roofers a durable coverboard that keeps projects moving forward.


A versatile and reliable solution for commercial roofing assemblies

As you can see in the video above, DEXcell Cement Roof Board’s unprecedented versatility provides installers with a lightweight roofing panel that is easy to handle, cut and install — even in the most extreme work environments. In addition, DEXcell can help extend the life of commercial roofs by providing a smooth, dense surface for the membrane and a protective layer for the roof’s insulation.


How do you install DEXcell Cement Roof Board?

While each commercial roofing project is unique, here are some basic steps to keep in mind as you plan and install cement overboard.

  • Preparation: Ensure the roof structure is properly prepared and has the necessary underlayment in place.
  • Measuring and cutting: Measure and mark the area where you will install the DEXcell Cement Roof Boards. Score the board and snap along the scored line for a clean cut.
  • Layout and placement: Starting at one corner of the roof, lay the first DEXcell board in place. Stagger the board joints, as well as joints in insulation below, for added strength and stability.
  • Fastening: Attach the DEXcell boards to the roof structure using approved fasteners or adhesives in accordance with system specifications.

“There are a lot of environmental factors that can play a part in what the roof system is going to do,” noted Fuller. “With DEXcell cement board, because of its low water absorption, it will actually keep water from getting into the roof.”

To ensure the right solution for a wide variety of roofing systems, DEXcell Cement Roof Board is offered in the following sizes:


DEXcell Cement Roof Board also provides weather and resiliency benefits, including:

  • Improved wind uplift rating of the system
  • Reduced impact of foot traffic on the roof
  • Smooth surface to install a new roof system in a retrofit application
  • Decreased amount of noise entering the building

In addition, it can also be used on the roof side of parapet walls and is manufactured to meet ASTM C1325 compliance.

View the DEXcell product guide to explore the benefits of all DEXcell products.