Single Ply Roofing Basics

Single Ply Roof in use at an airport
Photo Peak Roofing Systems

Single Ply roofing membranes provide a variety of materials to choose from. Their main characteristic is that they are designed to be installed in one layer. They also exhibit great flexibility, and they're resistant to UV radiation, which is superior when compared to other products. It is usually black or white finish and glued, fastened, or install directly over roof insulation material.

Types of Membranes

Single-ply membranes can be generally categorized into two groups: ​Thermosets and Thermoplastics. Thermoset membranes are compounded from synthetic rubber polymers, and the most commonly used polymers are EPDM, CSPE, and Neoprene.​​​​

Thermosets membranes are ideal for large roof areas because their manufacturing size is ideal for reducing or minimizing seams. The majority of EPDM thermoset black membranes have carbon black as an additional component, which increases the UV protection. In the case of white membranes, the manufacturer adds titanium dioxide, increasing the reflection property against UV rays.

Seams on thermoplastic single-ply membranes can be hot-air welded together to form cohesive laps. When thermoplastic membranes cool, they return to their original material type.

Two of the most commonly used thermoplastic single-ply membranes are PVC and TPO, both of them plastic-based materials. Thermoplastic membranes are usually manufactured to include a reinforcement layer, normally polyester or fiberglass, that provides additional strength and stability.

Both types of membranes are highly flexible and resistant to ultraviolet radiation. These types of membranes are relatively easy to install, but normally are also incompatible and cannot be used in combination with other single roofing systems.

Single Ply Roofing Installation Methods

The type of installation for the single ply roofing will depend on each particular situation and building. A ballasted roof might be the best and preferred installation method when the structural roof is capable to withstand the additional loads. Nonetheless, in the case where the roof has a slope greater than 1" in 6", then this method might not function properly.

A steel or wood roof might be ideal for mechanically fastened single-ply membrane roofing. Mechanically fastened single-ply roofing might be used on all types of slopes without limitations, and they are one the preferred option in hurricane-prone areas.

A fully adhered single-ply roofing might be another option for you to consider. If you choose this solution, the membrane needs to be attached using an adhesive recommended by the manufacturer, and it might be asphalt, solvent-based, or water-based adhesive. The finished surface will be smooth and can be used along with colored membranes to provide pleasant aesthetic surfaces using this installation method.

Single Ply Roofing Cost

The cost associated with the material and installation can vary widely depending on roof conditions, the attachment used, and the type of membrane being installed. Single-ply roofing is priced per square foot, and an average price for materials and installation of a 60 mil roof may range from $3 to $5 per square foot. As a starting point and if you are working on a proposal, you can use the following numbers for your cost estimate:

  • EPDM Rubber cost of material is about $1.50 per sq foot (excluding insulation), making the cheapest single ply roofing membrane.
  • TPO roofing is about $1.70 per sq foot (excluding insulation).
  • PVC roofing is about $1.90 per sq. foot (excluding insulation).

The Pros of Single Ply Roofing

  • Excellent against acid rain conditions
  • Excellent performance under dramatic weather changes
  • Will not suffer major problems under the presence of chemical materials
  • Wide variety of grades available to choose from(grades are the type of protection desired from the product)
  • Lightweight product
  • Excellent reflective properties
  • Easy to install
  • Economic feasible

The Cons of Single Ply Roofing

  • A thinner surface that can be easily punctuate
  • Relatively short lifespan
  • Seam problems might arise
  • Can be susceptible to water retention problems