You may have heard the term “roofing substrates” in passing. But do you know what it means? It’s not all that complicated.
In the following post, Roofer’s Guild will discuss different roof substrates and explain their pros and cons.
Key Takeaway
A roof substrate provides a frame for securing a weatherproofing roof layer for protection from the elements.
What is a Roofing Substrate?
A roofing substrate is any structure onto which you can install a roof coating or roofing system. It’s sort of like the support system for the roofing that you can’t see with the naked eye.
There are many different types of roofing substrates available, depending on what kind of building you have and what type of roofing system you want to be installed on top of it. As such, you may have many questions regarding which type of roofing substrates would be best for you.
Types of Roofing Substrates
To understand roofing substrates, you have to start with the basics. A roof isn’t just the planks of wood on top of your house or commercial building. It is made up of many layers.
Many people don’t realize that their shingles aren’t the core of their roofs. Commercial coatings and shingles are just means of waterproofing or insulating a building.
Roofers must install waterproofing layers and membranes on top of something (to be secured) because the surface they are attached to is the roofing substrate, sometimes called rigid sarking, roof decking, or underlayment. You should never see your roofing substrate if everything is as it should be.
Roofing substrates need to be moisture-resistant (although not fully waterproof), so they are typically made from timber boards, OSB, or plywood.
While roofing substrates are not necessarily needed to provide waterproofing protection to the building, certain types can offer this and other types of security – such as seismic uplift protection.
The primary role of a roofing substrate is to provide a solid frame onto which you can secure the weatherproofing layer of the roof.
There are lots of options when it comes to roofing substrates, though. Depending on where you live, you may be limited to certain types based on local building codes. Here is a list of the most common types of roofing substrates.
Plywood
Plywood is a prevalent material used to build roofing substrates. The benefits of plywood roofing substrate are that it is an affordable material and relatively easy to install.
However, while most contractors worth their salt will easily handle plywood substrate installation, they still must exercise caution.
That’s because the downside to plywood substrates is that a 1/8″ gap needs to be allowed, or else the panels will buckle. There are also some inherent weaknesses with plywood. Over time, they can become delaminated, and the boards will begin to pull apart.
SPF Substrates
SPF stands for Spray-In-Place Foam. It hasn’t been used for very long as a roofing substrate, but it works well with Conklin roofing systems.
One of the main benefits of this type of roofing substrate is that roofers can use it to impart a pitch to a flat roof. It also works well as a roof insulator.
The downside of this type of roofing substrate is that it needs to be reinforced to avoid degradation from ultraviolet light. Another downside is that it depends on the quality of foam installation laid down beforehand.
Solid Timber Boards
Solid timber boards are usually made from a naturally durable and water-resistant species of wood. They can also be treated with a preservative.
The good thing about stable timber boarding is that it provides remarkable resistance against warping if done correctly. Warping and shrinkage usually occur when plain-edged panels are used instead of jointed panels.
Solid timber boards are prone to shrinking and warping when plain-edged panels are used. While plain-edge panels are cheaper, jointed panels will provide more protection in the long run.
Concrete
Concrete can also be used for roofing substrates. They are most commonly used for multi-story buildings. By far, the best thing about concrete for roofing substrates is that they provide outstanding structural integrity. Also, as mentioned earlier, they are ideal for multi-floor buildings.
One of the downsides of using concrete for your roofing substrate is that you are limited in what type of roof coatings you can use. Generally, you should only cover concrete substrates with non-bonded or partially bonded coating systems.
Metal
There are several metal roofing substrate materials on the market. However, the most common and practical are aluminum and galvanized steel. Metal roofing substrates are commonly used in commercial construction to provide strength and durability for more significant buildings.
Aluminum is especially beneficial to use as a substrate in areas with high humidity due to its inherent moisture resistance. Aluminum is also lightweight (it doesn’t stress the building structure) and strong (it provides a solid base for most types of roof coatings).
The downside to metal roofing substrates is that they do not provide a continuous surface. As a result, they typically have to be used to supplement timber substrates.
Get Help With Roofing Substrates
Whether you are installing a new roofing substrate or needing repairs on your existing one, you must work with a professional.
Your building – whether it be your home or your business – is too important to leave in the hands of amateurs. In addition, a compromised roofing substrate can damage the structural integrity of the entire building.
That’s why we encourage you to work with a professional roofing company. At Roofer’s Guild, we provide marketing services for professional roofing contractors from around the country.
You can find a local contractor on Google search who will install or repair your roofing substrate professionally – no matter what type you need/have. So start searching now.
