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Single Ply versus Foam

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Single Ply vs SPF Comparison

Owners and managers of commercial buildings are often trying to choose from several different types of roofing to install on their building. The questions are usually something like which is best for my building?; which will last the longest?; and which will require the most maintenance?

At Armadillo Roofing & Exteriors, we want to make sure our clients have all the info they need to make the best possible decision. Here, in this blog post, we’ll look at the differences between 2 materials used extensively for commercial flat roofing – Single Ply and SPF (Spray Polyurethane Foam).

Single-Ply Membrane Roofing

Single Ply creates a layer of protection on your commercial property by chemically bonding sheets of synthetic materials or rubber to insulation or ballasted. The 2 main types of Single Ply membranes are EPDM (Ethylene Propylene Diene Terpolymer) and TPO (Thermoplastic Polyolefin). There are differences in their energy saving qualities, their installation and their chemical makeup.

SPF – Spray Polyurethane Foam

SPF, or Spray Polyurethane Foam, is sprayed on, then expanding to foam which creates a solid cover over the whole roof. This technology was created in the 1960’s  for commercial, industrial and residential properties.

Expense Comparison

Single Ply Roofing Systems – For EPDM the cost can range between $4 and $8 per square foot, and for TPO it can range between $3.50 to $7 per square foot, which includes materials and a warranty for labor.

Spray Foam Roofing – Usually, spray foam roofing systems will typically would be between $4 and $7 per square foot in labor and materials, depending on the thickness required and the structure of the building.

Installation Comparison

These systems have similar beginnings in their installation processes but differ in the overall process.

Single Ply Roofing Systems – The insulation is installed after the substrate is prepped by either removing the existing roof or by cleaning it thoroughly. There are several  insulation options that owners and managers can choose from.

The insulation layers are installed and covered by a cover board after the substrate is prepped. Then, with adhesive or mechanical fasteners, the membrane is attached to the cover board. When the time comes to adhere the membrane’s seams together is where the differences between TPO and EPDM occur. For TPO, a hot air gun is used to melt  the membrane seams to fuse them together. With EPDM this is accomplished with seam tape.

Commercial Flat Roofing ContractorsSPF Roofing Systems – Once again, the existing roof must be prepared before beginning the install process for SPF. However, there is no need to strip off the existing roof materials. The substrate is prepared by removing all dust, contaminants and dirt.

Then, the polyurethane foam is sprayed on over the top of it. The foam is created by mixing two liquids together. As they are sprayed on together, they combine and expand into a solid foam surface. It’s then coated with a layer, or layers, of either an acrylic or elastomeric silicone coating that has granules embedded in it.

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Single Ply roofs can last as long as 30 years if installed and maintained correctly. Here are some of the pluses of single ply roofing systems:

  • Long History – buildings have had EPDM roofing systems installed on them for over 60 years. many studies and testing have been done on these roofs over the years.
  • Insulation Choices – Single Ply does not include an installation factor, opening up a wide variety of choices to choose from to insulate the property.
  • High Fire Resistance Rating – During their manufacture, EPDM and TPO have fire retardant chemicals added to them for Class A fire resistance.
  • Highly Reflective – TPO is usually highly reflective with a white color. EPDM, on the other hand has a natural dark color, sometimes almost black.

SPF roofing systems, when correctly installed and maintained, can last as long as 60 years. Here are some of the other benefits of SPF:

  • Highly Energy Efficient – It has a high R value per inch due to the moisture, air and thermal barriers built into it.
  • Very Durable – The chance of cracking or splitting is reduced  because of its ability to expand and contract with the building.
  • Seamless Construction – there are no seams or joints, which are typically the most vulnerable areas for moisture to invade, making it very waterproof.
  • Environmental Compatibility – Since the existing roof does not need to be removed, there is very little waste and debris to fill landfills.


Single Ply Roofing – Here are a few of the disadvantages of Single Ply roofing systems:

  • Lack of Durability – Since there is no hard top layer on single ply roofing, it can be susceptible materials and screws being forced into and through its rubber membrane.
  • Seams are Vulnerable – Seams are an area that can be vulnerable to moisture and wind, making for increased vulnerability to damage.
  • Roofing Equipment and Accessories – Things such as skylights or vents that penetrate the roof need particular care when the installation takes place.
  • The Sun’s Rays – UV rays that shine directly onto the roof will deteriorate the adhesives over time.

SPF Roofing – Here are a few minuses to keep in mind about SPF roofing systems:

  • The Right Contractor – you will need a commercial roofing contractor that has extensive experience with this method to ensure that it’s completed correctly.
  • Short Window for Installation – Windy, cold and rainy weather is not conducive to the installation of SPF, making for a limited window to install it.
  • Overspray Danger – If windy, or wind comes up during the install process, since the material is sprayed on, it can be carried to cars and personal property.
  • Few Color Options – There’s pretty much 2 choices currently, gray or white.
  • More Maintenance – You’ll need to have SPF roofs inspected at least twice annually.

Both of these roofing systems have their advantages and disadvantages. Each property manager or building owner will need to make their own decision regarding which works best for them and their particular building.

Armadillo Roofing & Exteriors (512) 333-7663, provides commercial flat roof repair, commercial flat roof replacement and commercial flat roof installation services to Austin, Texas and the surrounding communities. We have been providing commercial roofing services to the area for over 15 years. When you need honest advice about your choice for a flat roofing system, please give us a call.

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