Cover Boards: The One Roofing Product You Should be Using

February 8, 2022

During the replacement or installation of a new commercial roofing system, you’ll often come across a variety of common roofing products being mentioned if you pay close attention. Only a few occasions will you hear of a cover board, so what is a cover board, and why is it important? We’ll answer this question by shedding light on this component which is fast gaining favor among roofing experts and property owners. Any Maryland company specializing in roof repairs and maintenance advises their clients on cover boards’ importance in getting the best and durable commercial roofing system.  

What is a Roof Cover Board?

A cover board is a substrate made of different materials set between the insulation and the membrane layers. It was initially designed as a barrier that offered a protective cover for the insulation underneath it. After its various advantages came into the limelight, it is now widely accepted as a crucial roofing component, and its use is gaining traction.     

Common Types of Commercial Cover Boards

All manufacturers of all membrane types allow the use of cover boards. However, it’s advisable to reach out to them for advice on the approved type of cover boards most compatible for use alongside their particular membrane. There are many types of cover boards; we shall look at a few most common ones;


This cover board is made of organic and inorganic materials, a mix between wood fibers and volcanic glass bonded with cellulose binders. It is well known for its perfect fire resistance capabilities and ability to change dimensions when wet.  

Wood Fiber:

Made of wood fiber and bonded with resin. They’re widely used in hot-mop and torch systems.  

Gypsum Fiber:

This is a fiber-reinforced gypsum board with uniform composition and is versatile with most roofing systems. It has the highest wind uplift while also protecting against moisture and moss growth.    

Gypsum Board:

This cover board type is made of a gypsum core and is sometimes primed with a factory laminated fiberglass mat facer.   

Mineral Fiberboards:

This cover board comprises compressed stone wool or mineral fiber and is best known for its sound properties. Widely used in asphaltic roof systems,  

Top Reasons You Should Use Cover Boards

The National Roofing and Contractors Association (NRCA) recommends using non-combustible roof cover boards, terming them critical in extending the roofing systems lifespan. They enhance the roof membrane system in many ways, leading to the prevention or mitigation of potential roof damage. Let’s look at some of the reasons below;

Protects the Roof System against Weather Vagaries

Storms and hailstones are a pretty common occurrence in a large area of the US. Sometimes, hailstones can be large and voracious enough to wreak havoc on the entire roofing system. A cover board can protect the insulation if a large hailstone shatters and penetrates the top roof cover.  

Improves Fire Ratings

Some insulating materials are often combustible; a cover board protects it by being an extra layer of resistance in case of a fire. This can help in preventing the overflow of fire into other nearby buildings.       

Protects Insulation from High-temperature Damage

Some insulation types, like polystyrene, can easily be damaged by high temperatures common with asphalt or torch applications. A cover board protects such heat intolerant materials as it is placed over the insulation before the membrane is placed.   

Reduces Condensation Associated Performance Problems 

Roof assemblies with no cover boards run the risk of performance problems brought about by condensation within the joints of the roof assembly. Installing a cover board helps seal off the joints within the insulator, eliminating the risk of condensation around them. 

Creates a Moisture Buffer Between Insulation and Membrane

Cover boards create a moisture buffer zone between the insulation and the membrane and, as a result, reduce blistering often due to trapped moisture between the membrane and the insulation. A porous cover board will allow built-up vapor pressure to pass through, reducing the likelihood of blisters forming.  

Provides a Protective Cover for the Insulation During Installation   

The roof is often burdened with loads of different nature during the installation process, ranging from traffic, snow, and wind. The insulation may be damaged from this weight and lead to the formation of voids and ridges. A cover board helps prevent or reduce the impact of such damages by offering protection through effective weight distribution. 

In a nutshell, cover boards can be very sustainable and resistant to wear and tear. For the most effective protection of your roof repair or assembly, evaluation of compatibility between a cover board type to be used alongside other materials making up the roofing system is necessary.  

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