Commercial Roof Membranes: Which Type Is Right for Your Project?

Author: Lee Polevoi | January 9, 2025

Roof membranes are an essential element in the proper care and maintenance of commercial buildings, and a variety of roof membrane types offer options for different regions and weather conditions. A roof membrane helps protect warehouses, factories, office buildings and more against unwanted leaks that can lead to significant structural damage.

The best roof membranes provide sturdy, weather-resistant and waterproof defense against adverse climate conditions. In this way, they add significantly to a commercial roof's life span. What's more, in most cases, these indispensable roof covering materials require little regular maintenance after installation.

Here's a quick look at roof membrane types for flat or low-slope commercial buildings.

Thermoplastic Polyolefin (TPO)

TPO is a single-ply material, a popular choice among roofing contractors intent on protecting the flat or low-slope rooftops of their customers' buildings. TPO's thermoplastic design enables the membrane to be heat-welded at the seams, thus generating a reliable, watertight layer over a roof.

TPO provides comprehensive protection from UV radiation and is known for its heat resistance. If your project is in an area with high temperatures and constant sunlight, you might choose a TPO membrane. In general, this roofing membrane comes in white or a light color, which contributes to energy efficiency and lower cooling expenses.

Ethylene Propylene Diene Monomer (EPDM)

EPDM roofing materials are made of synthetic rubber, an effective resource for withstanding UV rays, ozone exposure and other harsh weather conditions. Because it comes in large sheets, it's relatively simple to install. Like TPO, it's a good choice to consider for flat or low-slope commercial roofs.

EPDM is also supple and elastic, though occasionally prone to shrinkage. This attribute permits expansion and contraction as temperatures change. Depending on the type of design, EPDM membranes can closely adhere to a roof substrate, or be fastened or ballasted, adding to its waterproofing qualities. EPDM usually comes in black and white (both colors help produce greater energy efficiency).

Modified Bitumen (Mod Bit)

This asphalt-based roof membrane is ideally suited for commercial buildings with low-slope roofs. Because the asphalt material is combined with plastic or polymerized rubber (and then fiberglass-reinforced), mod bit is both durable and malleable — a proven method for waterproofing a commercial roof.

Modified bitumen roofing is designed to last a long time, up to 20 years (or longer, if accompanied by proper maintenance). Like some other roof membrane materials, it can handle challenging climates, while also standing up well to ongoing foot traffic. Plus, it's easy to install, with comparably fewer expenses relating to time and labor.

Polyvinyl Chloride (PVC)

This thermoplastic membrane is a popular choice for commercial buildings with flat roofing. Two layers of PVC with polyester material provide a strong fortification against heat and other challenging natural elements.

PVC is exceptionally resistant to chemicals, making it the roofing membrane of choice for industrial structures with exposure to potentially damaging substances. PVC is also fire- and grease-resistant, making it a smart choice for restaurants and other facilities involved in the production of food.

This membrane is not generally considered to be the best choice for commercial buildings in a cold environment, as ice and other cold-weather conditions can shatter PVC membranes. PVC can be more costly than EPDM roofs, though it usually has a longer life span than TPO.

Choosing the Right Roof Membrane

In general, roofing contractors and business owners can determine the right option for roofing membrane selection, based on:

• Type of business
• Location of business
• Status of the existing roof
• Desired life span of the roof

A customer's budget is also a key factor to consider when recommending the right type of roofing membrane. In the long run, it may be best to advise customers on roofing membranes that cost more up front but lead to significant savings in longevity and energy efficiency. Building owners who opt for less expensive materials may face more costs down the road (including maintenance, repair and replacement).

Installation Tips

The installation of roofing membranes differs somewhat depending on material type. But some general principles apply:

• Don't pull the membrane material too tightly under tiles. If the membrane becomes too stiff, there's a chance it will tear and water will get caught behind the tiling.
• Pay close attention to detail membrane work around skylights, HVAC units and other objects that are a permanent part of a commercial rooftop.
• Don't allow the membrane material to drop over into the guttering.

In all cases, it's important to stick with a manufacturer's installation recommendations. But also be flexible when encountering any specific challenges while laying out the membrane material. Your customers will greatly appreciate the care with which you handle this process.