8 Types of Single-Ply Roof Membranes

By Roof Online Staff • Last updated October 22, 2022

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Introduction

The majority of all new commercial roof installations use a single-ply roofing system.

Although modifications and reformulations of single-ply materials sometimes lead to a roofing manufacturer designating their product as a new type of membrane, there are 8 commonly-recognized types of single-ply roof membranes found on roofs today.

We list them here and provide some basic information about each one.

According to the Glossary of Roofing Terms published by the International Institute of Building Enclosure Consultants (IIBEC), the official definition of single-ply roofing is as follows:

“A roofing system in which the principal roof covering is a single layer flexible membrane, often of thermoset, thermoplastic, or polymer modified bituminous compounds. Generally there are six types of single ply roofing systems 1) Fully-adhered, 2) Loose-laid, 3) Mechanically-fastened, 4) Partially-adhered, 5) Protected membrane roof, and 6) Self-adhering.”

These six types refer to the attachment method of the roof systems, not to the type of material used.

Attachment Methods for Single-Ply Roof Membranes

The overwhelming majority of single-ply roof systems are installed using one of three methods:

Fully-adhered, which means that the entire single-ply roof membrane is bonded to the cover board or insulation with membrane adhesive. The rest of the roof system may be attached to the roof deck using either adhesives or fasteners, but no fasteners will penetrate the roof membrane.

This method typically results in the longest-lasting roof, everything else being equal.

Mechanically-attached, which most often means that the roof membrane sheets are individually fastened down into the roof deck using a line of fasteners which are normally hidden inside the seams which join the sheets together, where the sheets overlap.

Sometimes a mechanically-attached system will not use the seams, and the lines of fasteners will simply be installed at regular intervals across the roof, each line being covered by a separate strip of membrane material.

Sometimes batten strips (flat, narrow strips of plastic or metal) will be included along the fastener lines for increased securement.

This method normally results in the second longest-lasting roof, everything else being equal.

Ballasted, which is an attachment system in which all of the layers of the roof system are loose-laid, without using any fasteners or adhesives. Ballasted systems depend on ballast weight to hold the entire roof system in place.

The ballast is usually installed directly on top of the single-ply roof membrane, although a geotextile may be laid over the membrane to protect it from the ballast.

The ballast used for securing roof systems normally consists of river-washed stones (no sharp edges), concrete pavers, or a combination of the two.

It’s common to see stone ballast used on most of the roof with the heavier and more stable concrete pavers installed at the corners for increased wind resistance.

The ballast is installed across the entire surface of the roof at an installed weight of 10 – 20 pounds per square foot.

Ballasted systems usually have the shortest life expectancies, with the shortest warranty periods.

Is Modified Bitumen a Single-Ply Roof Membrane?

There is also some confusion in the roofing industry as to whether modified bitumen systems should be placed in the single-ply category or considered a built-up roof system. Over the years, we’ve seen various reputable roofing industry experts categorize modified bitumen as both.

Modified bitumen isn’t really built-up on site the way a true built-up roof system is, although a case can be made that out of all other roof systems, it’s most similar to a BUR. We prefer to categorize modified-bitumen as it’s own separate type of roofing.

We don’t consider modified bitumen to be a single-ply roof membrane for the simple reason that almost all modified bitumen roofs have two plies. You can read more in our article on modified bitumen.

CPE (Chlorinated Polyethylene) Single-Ply Roof Membrane

A CPE single-ply roof membrane after a rain.
A CPE single-ply roof membrane after a rain.
  • Colors: White, Gray
  • Attachment Method: Fully-Adhered, Mechanically Fastened, Ballasted
  • Seaming or Patching Method: Hot Air Welded
  • Asphalt Compatibility: Good
  • Resistance to Oils, Coolants, and Grease: Excellent
  • In Use Since: Late 1960’s

CSPE “Hypalon” Roof Membrane (Chlorosulfonated Polyethylene)

  • Colors: White (typical), Various Others
  • Attachment Method: Fully-Adhered, Mechanically Fastened, Ballasted
  • Seaming or Patching Method: Hot Air Welded (typical), Adhesive
  • Asphalt Compatibility: Good
  • Resistance to Oils, Coolants, and Grease: Animal Fats – Excellent; Petroleum – Fair
  • In Use Since: Mid-1960’s, US production stopped in 2010

To learn more about Hypalon, see our Hypalon (CSPE) Roofing page.

EPDM Roof Membrane (Ethylene Propylene Diene Monomer)

An EPDM single-ply roof membrane
An EPDM single-ply roof membrane
  • Colors: Black (typical), White
  • Attachment Method: Fully-Adhered, Mechanically Fastened, Ballasted
  • Seaming or Patching Method: Adhesive or Adhesive Tape
  • Asphalt Compatibility: Fair
  • Resistance to Oils, Coolants, and Grease: Poor
  • In Use Since: 1970’s

To learn more about EPDM, see our EPDM Roofing page.

KEE/PVC Roof Membrane (Ketone Ethylene Ester + Polyvinyl Chloride)

KEE/PVC Roof Membrane
Installing a KEE/PVC roof membrane (image courtesy Mule-Hide Products)
  • Colors: White, Gray, Tan, (custom colors available)
  • Attachment Method: Fully-Adhered, Mechanically-Fastened, Ballasted
  • Seaming or Patching Method: Hot Air Welded
  • Asphalt Compatibility: Good
  • Resistance to Oils, Coolants, and Grease: Good
  • In Use Since: 1980’s

PIB Roof Membrane (Polyisobutylene)

PIB roof membrane
PIB roof membrane (image courtesy FDT Flachdach Technologie)
  • Colors: Black, Gray, White
  • Attachment Method: Fully-Adhered, Mechanically-Fastened, Ballasted
  • Seaming or Patching Method: Adhesive or Hot Air Welded
  • Asphalt Compatibility: Good
  • Resistance to Oils, Coolants, and Grease: Poor
  • In Use Since: 1930’s

PVC Roof Membrane (Polyvinyl Chloride)

A newly-installed PVC single-ply roof membrane
A newly-installed PVC single-ply roof membrane
  • Colors: White, Gray, Tan, (custom colors available)
  • Attachment Method: Fully-Adhered, Mechanically-Fastened
  • Seaming or Patching Method: Hot Air Welded
  • Asphalt Compatibility: Poor
  • Resistance to Oils, Coolants, and Grease: Fair
  • In Use Since: Late 1960’s

To learn more about PVC, see our PVC Roofing page.

TPE Roof Membrane (Thermoplastic Polyolefin Elastomer)

TPE roof membrane
TPE roof membrane (image courtesy Armormat)
  • Colors: Gray
  • Attachment Method: Fully-Adhered, Mechanically-Fastened, Ballasted
  • Seaming or Patching Method: Hot Air Welded
  • Asphalt Compatibility: Good
  • Resistance to Oils, Coolants, and Grease: Animal Fats – Excellent; Petroleum – Poor
  • In Use Since: 1990’s

TPO Roof Membrane (Thermoplastic Polyolefin)

A TPO single-ply roof membrane during installation
A TPO single-ply roof membrane during installation.
  • Color Availability: White, Gray
  • Attachment Method: Fully-Adhered, Mechanically-Fastened, Ballasted
  • Seaming or Patching Method: Hot Air Welded
  • Asphalt Compatibility: Good
  • Resistance to Oils, Coolants, and Grease: Animal Fats – Excellent; Petroleum – Poor
  • In Use Since: 1980’s

To learn more about TPO, see our TPO Roofing page.