Single-Ply Roofing Membranes and Comparisons of Different Roof Systems

Our commercial roofing service experts know that building managers and owners in the East Texas region are typically overwhelmed by the many options available for low-slope roofs. Single-ply roofing membranes have three main group types. All single-ply roofing systems are fairly complex, and some have complex names or abbreviations to cause even more confusion.

Let’s talk about the most common and most effective single-ply roofing membranes across East, Central and North Texas.

What is Single-Ply Roofing? 

A single-ply membrane roof refers to a waterproofing and flexible material that typically gets installed on flat or gently sloped commercial and industrial roofs. These are prepared as a single or double layer. 

Engineered to perform for many years and be cost-effective for large buildings, some materials like thermoplastic (TPO) membranes can add energy efficiency that can help businesses lower their heating and cooling costs. 

Group 1: Thermoset Membrane Roofing

The polymer materials in these single-ply roofing membranes chemically crosslink. This means that chemical adhesives applied at the seams cures or vulcanizes the membrane strips into one giant membrane. There are several players in this category, which is also defined as the synthetic rubber membrane group.

The Five Common Subcategories of Thermoset Membrane Roofing:

• Ethylene propylene diene terpolymer (EPDM)
• Chlorosulfonated polyethylene (CSPE)
• Epichlorohydrin (ECH)
• Neoprene (CR)
• Polyisobutylene (PIB)

The most common thermoset roof membrane is EPDM. This frontrunner of the pack will be our comparison product. Note EPDM’s main characteristics:

• Sheet widths range from 7.5 feet to 50 feet wide.
• Sheets are typically 45 millimeters and 60 millimeters thick.
• Seams are sealed using liquid adhesives or special formulated tape.
• The membranes commonly are black, but white is available.

Group 2: Thermoplastic Membrane Roofing

This family of single-ply roofing membranes are like the thermoset roofing membranes, but there’s no chemical cross-linking or vulcanization. The membrane strips are heat or chemical welded to create a single ply. Proper welds are as strong as the material.

There are four common subcategories of thermoplastic roof membranes:

• Thermoplastic Olefin (TPO)
• Chlorinated Polyethylene (CPE)
• Polyvinyl Chloride (PVC)
• PVC Alloys or Compounded Thermoplastics
  • Copolymer Alloy (CPA)
  • Ethylene Interpolymer (EIP)
  • Nitrile Alloys (NBP)
  • Tripolymer Alloy (TPA)

The most common thermoplastic roof membranes are PVC (chemical weld) and TPO (heat weld). PVC is common simply because it was the frontrunner until TPO came into its own with more adopters. Thus, for this group, we will look at TPO when comparing single-ply roofing membranes.

TPO membranes are produced by calendering with lamination, extrusion with lamination, or extrusion-coating techniques. TPO sheets are a blend of polypropylene and ethylene propylene polymers and usually are reinforced with polyester. Note TPO’s main characteristics:

• Sheet widths range from 6 feet to 12 feet wide.
• Sheets are typically 40 millimeters to 100 millimeters thick.
• Seams are sealed by heat welding with hot air.
• TPO membranes commonly are white, but can allow for a colorant.
• Flame retardants are added.
• UV absorbers and other proprietary substances are added as needed.

Group 3: Modified Bitumen Membrane Roofing

These membranes combine asphalt with modifiers and reinforcement materials. They are often a ‘sandwiched’ roofing material. These materials can perform well, but they are not as advanced as the other two groups.

Many commercial roofers refer to modified bitumens as ‘torch-down’ roofs because a large flame-throwing torch melts the asphalt so that seams can be joined together.

The two types of modified bitumen (MB) roofing membranes:

• SBS polymer-modified bitumen membranes commonly are installed via hot mopping asphalt (similar to BUR systems) or cold adhesive. Some SBS modified membranes are self-adhering and contain an adhesive backing.
• APP polymer-modified bitumen membranes typically are heat-welded or torch-applied. Consumers should be cautioned that NRCA does not recommend torch-applying a modified bitumen membrane sheet directly to a wood deck.

Generally, APP modifiers impart a ‘plasticized’ quality to asphalt, and SBS modifiers impart a ‘rubberized’ quality to asphalt. MB membranes and EPDM, a thermoset membrane, often are confused by consumers because of colloquialisms used by roofing contractors. MB and EPDM membranes are sometimes called “rubber roofs.”

Modified bitumen is inexpensive, easy to apply in the case of SBS, and great for DIY types. This combines with its short lifespan make it a non-competitor for larger commercial roofing spaces.

Comparing TPO Roofing & EPDM

These two roofing membrane types are the ones you’ve likely heard the most about. If you have a low-slope (flat) commercial roof, it most likely has a leading thermoset or thermoplastic membrane on it.

Our head-to-head comparison of TPO vs. EPDM takes into account a range of good-to-top tier products per each single-ply membrane type. We awarded each a +1 or -1 to give a final tally of overall prowess of each membrane type, if it gave more options or value, or had a deficit or negative detractor.

Comparison Table: EPDM and TPO Membrane Roofs

——————–	EPDM	TPO
Warranty Timespan	10-35 Years	10-35 Years
Warranty Value	Average	Wide
Cost Effective	Yes	Yes
Lifespan	20-50 Years	15-50 Years
Thickness	45-60 Millimeters	40-100 Millimeters +1
Maintenance Costs	Medium -1	Low
Energy Savings	Little to None	Light to Significant +1
Summer Heat Buildup	Yes -1	Little
Suitable Climate	Colder -1	Most
Environmentally Friendly	Yes: Recycled Materials	Yes: 100% Recyclable
Color Options	Black & White	Many +1
Inexpensive Repairs	Typically	Yes +1
Track Record	Solid +1	Short -1
Sheet Size	Medium to Huge +1	Small to Medium
Chemical Resistance	Very Poor -1	Excellent +1
Requires Skill to Install	Yes	Yes
Pollution From Runoff	None	None
Shrinkage With Heat	Some	Some
Failure After 10 Years	Moderate to Low -1	Very Low to None
Installation Speed	Average	Below to Above Average -1
Weather Rating	Average	Average to Very Good
Final Tally	-3	+3

When we’re comparing EPDM and TPO products, we get a six-point spread in favor of TPO roofing. As a GAF Master Elite roofing contractor, Stonewater Roofing uses the top-rated TPO roofing membrane lines made by GAF. When you combine the best products, top notch installations and the best warranty, TPO picks up two or three more points over EPDM.

Request a Free Quote on Single-Ply Roofing Upgrades

Call the commercial roofing professionals at Stonewater Roofing to learn more about upgrading your flat roofing to a TPO roofing membrane from GAF. We offer free roof inspection services for commercial roofs to get an honest assessment of its condition, and provide a free estimate for any repairs or replacement. 

Contact us to schedule your appointment today!