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Roof Substrate 101: Understanding the Basics of Roofing Materials

Posted on : April 20, 2023

Roof Substrate 101: Understanding the Basics of Roofing Materials

When it comes to choosing a roofing material for your home or building, there are many factors to consider. One key aspect of any roofing system is the roof substrate, which is the layer of material that provides the foundation for the other roofing materials, such as shingles, to be laid upon. While often overlooked, the roof substrate plays a crucial role in the durability, longevity, and overall performance of the roof. 

In this article, we'll provide an introduction to roof substrates and explain why understanding the basics of roofing materials is essential for anyone considering a new roof. Whether you're a homeowner, builder, or architect, this guide will help you make an informed decision when it comes to selecting the right roof substrate for your project.

What Is Roof Substrate? What Does Substrate Mean In Roofing?

The word substrate is used to describe several things. For example, the word substrate is commonly used in science to describe a material or substance that is being worked on or transformed when something else reacts with it. 

In the context of roofing, it is the layer of material that serves as the foundation for the roofing system. It is the surface on which the roofing material is installed, and it provides support and stability for the roof. The substrate is typically installed over the roof deck, which is the structural component of the roof, but sometimes the roof deck is considered the substrate itself.

The choice of substrate is an important consideration when designing and installing a roofing system. 

Why Do You Need To Consider Roof Substrates? 

Roof substrate or decking is the foundation of your roof.  To ensure that your roof performs at its best, you need to first consider the condition of your roof’s foundation. Let’s take a look at some of the reasons why you need to install a quality roof deck when you install a new roof. 

Provides A Stable And Strong Foundation:

The roof substrate is the base on which the rest of the parts of the roofing system are laid upon. A quality substrate for a roof provides a stable and strong structure for the roofing material to be installed on top of. This ensures that the roofing system can withstand the weight of the material, as well as wind, rain, and snow, keeping your interior safe from the harsh weather.  

Increases The Lifespan Of The Roof: 

A quality roofing substrate can help prolong the lifespan of a roofing system by providing a strong base for the roofing material. This helps prevent premature damage and wear and tear, which can significantly extend the life of your roofing system. This is crucial as both roof repairs and replacements can be costly depending on the damage. 

Helps Prevent Moisture Infiltration: 

Moisture infiltration is a major concern for roofing systems, as it can cause damage to the structure of the building and lead to costly repairs. A quality substrate helps prevent moisture infiltration by providing a barrier between the roofing material and the interior of your building. This helps to keep the roofing system dry and free from damage.

Types Of Roof Substrate

Now that you know what a roof substrate is and how crucial it is for your roofing system’s overall health and compatibility, it is time to move ahead and learn about the different roof substrates that you can use for your new roof installation. Here's an overview of different types of roof substrates commonly used in roofing systems: 

Wood Substrate: 

Wood Substrate

Wood has been used as a roofing substrate for centuries, and it remains a popular choice for many homeowners and builders. They are also known as traditional roof substrates. 

Wood substrates are typically made of plywood or oriented strand board (OSB), and they provide a strong and stable foundation for the roofing material. Wood substrates are easy to work with and most of the contractors have expertise in installing them, which can be an advantage when looking for a contractor who can handle the job.



Plywood is a type of wood panel made from thin layers, also known as plies, of wood veneer that are glued together in layers to form a flat sheet. Each layer of wood is oriented perpendicular to the adjacent layers, which provides strength and stability. Plywood is commonly used as a roofing substrate because it is strong, lightweight, and easy to work with. It is also resistant to moisture and can withstand exposure to the elements.



Oriented Strand Board (OSB) is another type of wood panel that is similar to plywood. However, instead of using thin veneer layers, OSB is made from wood strands or chips that are arranged in layers and bonded together with adhesive. OSB is a popular roofing substrate because it is less expensive than plywood and has good structural strength.

Metal Substrate 

Metal Substrate

Substrates made from different metals are also getting quite popular amongst homeowners and business owners alike. You can use metal substrates with a variety of roofing systems, including standing seam, corrugated, and metal shingle roofs.

Metal substrates are typically made of steel or aluminum and are commonly used for commercial and residential roofing systems. Metal substrates are lightweight and one of the most durable options available on the market. Not only will they last long on your roof, but they also provide excellent resistance to fire, wind, and hail. Since mostly steel is used, metal substrates typically offer termite resistance as well. 

Since it is much more durable than the standard plywood roof deck, metal roof substrates are quite expensive. Also, metals that are not of high quality can easily rust and be more prone to damage.                               

Concrete Substrate 

Concrete Substrate 

Concrete is a durable and long-lasting substrate that is commonly used for commercial and industrial roofing systems. Concrete substrates are made of precast concrete panels or poured in place on-site. They are heavy and provide excellent thermal mass, which can help regulate the temperature in a building. Concrete substrates are also fire-resistant and can withstand severe weather conditions.

Though perfect for flat roofs and multi-story buildings, there are some downsides. It can be more expensive than other types of substrates and finding a leak can be somewhat difficult due to the composition. 

Insulation Board 

Insulation Board 

Insulation board is an important type of substrate used for roofing systems, particularly for flat or low-slope roofs.

Insulation board is used to provide thermal insulation for the building and to help reduce heat loss or gain. It is typically made of rigid foam insulation, such as expanded polystyrene (EPS), extruded polystyrene (XPS), or polyisocyanurate (ISO), which provides excellent thermal performance. EPS is a lightweight and cost-effective option, while XPS has better moisture resistance and compressive strength. 

The choice of substrate will depend on several factors, including the type of roofing material being installed, the climate, building codes, and personal budget. It is important to consult with a roofing professional to determine the best substrate for your roofing project.

Factors That Affect Your Choice Of Roofing Substrate 

When choosing a roof substrate, there are several factors to consider. These include the following: 


The climate of the area where your residential or commercial building is located is an important factor to consider when choosing a roof substrate. For example, in areas with heavy rainfall, a substrate that is highly resistant to moisture, such as concrete or metal, is a better option than wood.

Building Codes: 

Building codes and regulations must be considered when selecting a roof substrate. Some codes may require certain types of substrates, such as fire-rated materials, for buildings in high-risk fire areas. It is important to consult with a professional roofing contractor who is familiar with local building codes to ensure that the selected substrate meets all necessary requirements.


Budget is an important consideration when selecting a roof substrate. Some materials are more expensive than others, and the cost of installation can also vary. It is important to balance the cost of the substrate with its quality and durability, as investing in a high-quality substrate can save money in the long run by reducing the need for repairs and replacements.

Other Important Layers Of Your Roofing System

In conclusion, choosing the right roofing substrate and understanding the different layers of a roofing system are crucial for ensuring the longevity and effectiveness of the entire system. 

Roof decking or substrate board is the first layer of the roofing system. Before you install a new roof, know about the other crucial layers of the roofing system. By understanding the different layers, building owners and contractors can make informed decisions about the materials and techniques that will best meet their needs.

Here are some of the other roofing components:

Best Roofing Services In Pittsburgh

McClellands Contracting and Roofing, LLC is a premiere roofing company that has been in the industry for years. We offer the best residential roofing services in Pittsburgh and the surrounding areas. 

We understand that different homeowners have different preferences, and this is why we offer to install several roofing materials such as:

  • Asphalt shingles
  • Metal Roofs 
  • Wood Shakes
  • Tile Roofs

Not only do we work on residential roofs, but we also work on flat roofing systems as well. Contact us today at (412) 353-5660 and book a free roof inspection with one of our experts.

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