A flat roof covered in bitumen sheets.

Roofing Membranes vs. Roof Substrates: A Comparison of These Two Roofing Terms

The roofing trade contains complicated terms and acronyms that may confuse commercial building owners unfamiliar with the industry. But you want to make the right choice regarding your building’s roof, so you decide to familiarize yourself with roofing terminology. Still, you’re not quite sure what the difference is between a roofing substrate and a roofing membrane and if you need both.

That’s where our experts at Heidler Roofing shine. We understand what it’s like to confuse some of the terminology associated with roofing because we were once there ourselves during the initial stages of learning the business. But after 63 years in the commercial roofing industry, we have learned plenty about several types of roofing elements.

Today, we’ll highlight some roof membranes and substrates comparisons so that you can better understand what we’re discussing with you during your roofing estimate.

What Is a Roofing Substrate?

A roofing substrate is a term used to describe the surface on which we apply roofing or waterproofing membranes. It may refer to the structural deck of the roof, an underlayment, or a coverboard, depending upon the roofing system used. It could even be a pre-existing roof system which we cover with a coating or new roofing materials.

There are many distinct types of roofing substrates, and those with an industrial or commercial building need specific ones. If we were to make a roofing membranes and substrates comparison, a way in that they are similar is that each roofing system has a substrate that works best for it, depending on the building and the business being conducted inside.

That’s why you need reliable and experienced roofing professionals like Heidler Roofing to provide you with the best advice for your commercial building.

Types of Roofing Substrates

There are several types of roofing substrates, and the one that is on your commercial building may be one of the following:

  • Open Framing—A type of substrate made of wood or metal framing with individual pieces of wood or steel connecting to form the roof’s frame. The building may need structural panels to support the weight of the roofing materials.
  • Solid Substrate—A type of substrate consisting of solid materials, such as plywood, oriented strand board (OSB), concrete, or metal.
  • Pre-Existing Roofing System—Contrary to widespread belief, applying new roofing materials doesn’t always mean a complete tear-off of your existing roof system. Your pre-existing roof could act as a roofing substrate, whether for a built-up roof or a single-ply roof membrane.

What Is a Roofing Membrane?

Now that you better understand one-half of our roof membranes and substrates comparison, let’s focus on the other half: roofing membranes. A roofing membrane is a term that describes the flexible or semi-flexible roof covering that primarily waterproofs a roof system. A membrane may consist of a single or several materials laminated together.

We at Heidler Roofing can handle several types of roofing membranes. We can recommend the best membrane roofing system for your building based on its current condition, your location, and what business you do.

For example, a few years ago, we helped Rise Bakery in York, PA, get rid of its ballasted EPDM roof because it was old and leaking water into production areas. We installed a FiberTite Membrane System because of its resistance to punctures, grease, and chemicals. The installation process went great, and everyone was happy with the outcome.

Roofing Membrane Types

Roofing membranes consist of asphalt-based systems, such as built-up roofing and modified bitumen roofing. It can also be one of the diverse types of single-ply roofing, such as EPDM, PVC, or TPO. Each has its unique characteristics and advantages, such as:

  • Built-Up Roofing—Sometimes called BUR, this roofing membrane is made of felt or reinforcing fabric layers. We build up these layers by overlapping them and infusing them with bitumen. They are typically topped with aggregates like stone or gravel. This roof membrane’s benefits include waterproofing, incredible durability, and good fire resistance.
  • Modified Bitumen—MB or Mod Bit roofing is also constructed in layers like BUR roofs, with a petroleum-based substance between the layers. This substance gives it a synthetic rubber appearance. Some advantages include easy installation without heat, durability, and reflectivity for energy savings.
  • EPDM—Ethylene propylene diene monomer, or EPDM, membranes are coated in adhesive and then rolled into place and broomed down for adhered roofing systems. For ballasted systems, the membranes are laid on the roof substrate and ballasted generally with gravel. Mechanically attached systems are adhered to the roof with plates and fasteners. This flat roof membrane provides wear, fatigue, impact resistance, and a waterproof seal.
  • PVC—This roof membrane acronym stands for polyvinyl chloride, a type of roof known as thermoplastics, which become soft when heated and rigid when cooled. We overlap this material on the top, and the seams are hot-air welded. PVC roofs have the following advantages: resistant to chemicals, fire, and grease, energy efficient, and recyclable.
  • TPO—Thermoplastic polyolefin, or TPO, roofs are a type of flat-roof membrane that is also thermoplastic, like PVC. It can adhere to the roof with a bonding adhesive or mechanically fastened with plates and fasteners. Its benefits include weather resistance, energy efficiency, and color options.

Roof Membranes and Substrates Comparison

Now that we’ve defined what each component is let’s look fully at a roof membranes and substrates comparison. First, while a roofing membrane can sometimes be a roofing substrate, a substrate can never be a membrane alone. It needs some roof material on top, whether a single-ply membrane or an actual roof coating.

Second, both are similar in that there is not one answer to the best type. It depends on your building, the climate and weather of your location, and what you do inside the building. Some roofing materials, like PVC, are better for places like restaurants and food manufacturers, while BUR might be better for industrial power plants.

The third roofing membranes and substrates comparison point is that you need professional advice from a commercial roofing contractor like Heidler Roofing. We’ll go up on your roof and perform an inspection to provide you with accurate recommendations and a thorough estimate. Our skilled craftsmen will explain the problem areas on your roof and suggestions to fix them.

Plus, we have affordable roof maintenance plans to help extend the life of your roof and reduce costly repairs by catching small problems before they turn into major catastrophes. Don’t wait any longer! Get legendary service for your roof today by the most skilled craftsmen in the Mid-Atlantic region at Heidler Roofing.