What Is A Cover Board And Why You Should Install One


Investing in a brand-new roof system is a smart decision that can protect your property from daily wear and tear, whether it’s natural, mechanical or even man-made. One important component is cover boards and today, we’ll discuss what these are and why you must install one on your roof.

What is a Cover Board?

A cover board is a key element in a roofing system. Made from different materials, a cover board is a thin substrate that is installed right between the insulation and membrane layers of your roof system. Cover boards are typically overlooked during the design process of a roof system but picking the right one can help the system installation and heighten the durability of your roof system.

Cover boards were initially used to function as a protective barrier that keeps hot asphalt or adhesives from causing any damage to the insulation underneath. Cover boards are also used to prevent blisters from forming in the roof system, which can happen due to insulation off-gassing getting into contact with adhesives.

These days, cover boards are relied on to give commercial roof systems more strength and durability. These are now widely accepted as a crucial roof element that supplements the roof design with a wide range of benefits such as:

  • Establishing a substrate for the installation of the membrane
  • Giving durability to your roof system
  • Bolsters impact resistance
  • Helps restrict external fire spread
  • Adds resistance to wind uplift
  • Produces a thermal and vapor barrier

Roof cover boards give an added layer of durability to a roof system to reduce the damage that is taken from natural elements such as hail, and other factors that include constant foot traffic, mechanical systems, wind-born rubble, and other hazards. This is done by placing the cover board material underneath the membrane and right over the insulation foam, thus giving more firmness for the membrane and protection for the insulation beneath.

Aside from their use as a substrate for the membrane, cover boards can also be installed as a thermal or a vapor barrier. Insulation can prove to be incendiary, so putting in a cover board is crucial as it can function as a deterrent to the spread of fire from outside the building to the insulation and straight into your building. Cover boards can also help improve interior fire resistance when put in as a thermal barrier.

Cover boards are also utilized in re-roof applications where the board is placed on a current roof system to give the new roof system an ideal substrate. However, there are reasons why some people elect not to have a cover board installed. The most prevalent reason is cost as the materials and the manpower needed to install these can put a dent into your bank account.

What are the Different Types of Cover Boards?

Roof cover boards are made of a wide variety of materials and you need to carefully consider this when selecting one for your roof system as this can impact its fire resistance, moisture resistance, uplift resistance and overall durability. Each type of cover board possesses multiple properties that make it different from others. The different kinds of cover boards include:

  • Gypsum Fiber: fiber-reinforced gypsum board that does not have a fiberglass mat facer
  • Gypsum: gypsum board with and without a factory laminated fiberglass mat facer
  • Wood Fiber: wood fiber mixed with a resin binder, which can be asphalt primed
  • Cement: cementitious base reinforced with mesh
  • High-Density Polyiso: compressed polyisocyanurate with a coat of glass-mat facer
  • Perlite: volcanic materials merged with minerals, fibers, and cellulose binders
  • Asphaltic: a combination of minerals and asphalt with a fiberglass facer
  • Mineral Fiber: compressed rock wool or mineral fiber
  • Plywood/OSB: compressed layers of wood bound with a resin, sometimes with veneer

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