spray foam roof at Lorain School

TPO vs SPF: Which Roof Is Better for Your School?


When we meet with building supervisors at school districts, they’re usually stuck on one roofing system…TPO. When we bring up SPF (Spray Polyurethane Foam), they have some questions:

  • Which type is cheaper?
  • Which provides better insulation?
  • Which is faster to apply?
  • Which is better on Tectum?

At West Roofing Systems, we want to make sure that building supervisors have the best information available. For this reason, we created an article that explores the differences between TPO and SPF roofing systems that’ll give you all the information you need in choosing the best roof for your schools.

The Basics


Thermoplastic Polyolefin (TPO) is a single-ply roofing membrane that is one of the fastest growing commercial roofing systems on the market. TPO roofing systems are made up of a single layer of synthetics and reinforcing scrim that can be used to cover flat roofs. The scrim is heated with a hot air gun that welds the seams together.

TPO Installation

TPO membranes are manufactured in sheets that are 10, 12 or 20 feet wide. TPO has gained industry acceptance with the white-colored, natural, reflective surface to reflect UV rays.

TPO Single-Ply Membrane Roofing


Spray Polyurethane Foam (SPF) is a combination of two chemicals that are heated and pressurized to spray as a liquid, which expands into a foam, and creates a solid layer across an existing roof.

Quick fact: SPF grows to 30x its size in 8 seconds…and you can walk on it in about one minute.

While SPF roofing is not the most known type of roofing material, the technology has been around since the early 1960s. An SPF roofing system can be used in any climate, and when correctly installed and maintained, can last over 50 years.

TPO vs SPF: Which roofing type is cheaper?

For an average 20,000 sq. foot roof, it will usually cost between $4.00 and $7.00 per square foot in materials and labor to install a typical SPF roofing system. This price range is for an SPF roof of average thickness and building structure.

For an average 20,000 sq. foot roof, it will usually cost between $3.50 and $7.50 per square foot in materials and labor to install a typical TPO roofing system.

NOTE: Pricing depends on variables such as:

  • Does the existing roof need removed?
  • Do cover boards need installed?
  • Are there any existing penetrations?
  • How accessible is the roof?
  • Any much more…

TPO vs SPF: Which roofing type is better for insulation?

An advantage with SPF is that it provides schools with more efficient insulation. This is important because HVAC costs can be high when trying to keep hundreds of students and faculty comfortable.

With SPF being seamless, it has an R-value of 6.7 per inch  (the highest rating of any standard roofing insulation ) vs TPO, which provides no insulation value.

TPO vs SPF: Which roofing system is faster to apply?

Speed is greatly important for school roofing projects. Schools only have 12 weeks of summer vacation without any students or staff around.

With unpredictable weather and roofing contractors scheduling jobs 2-3 months in advance, it’s important for schools to make sure the contractor can finish the job before school begins.

One factor that can increase the speed of a project is the type of material being laid down.

Quick fact: SPF can be laid down 50% faster than TPO.

A 20,000 square foot school, with SPF being laid down around 3,000 sq. ft/day, that’s a 6.6 day project. For TPO, the same project can take around 13.2 days. Add in a few rain outs and your project can take 2-3 weeks.

NOTE: Being able to shorten the project in half saves tremendously on labor costs.

TPO vs SPF: Which roofing type is better on Tectum?

If you’re a building supervisor at a school district, I’m sure you know about tectum. Tectum is the type of decking material that makes up most school roofs. Schools especially use tectum over a gym because it’s great for sound control and acoustics.

So which roofing option is better on tectum?

Hands down SPF!

Spray foam allows a contractor to tear off the old roof, get down to the tectum, and spray the foam overtop. No penetrations will be made.

With TPO, a contractor will have to fasten the TPO down with traditional plates and auger style screws, making penetrations in the tectum roof deck. Adhesive TPO is available over Tectum but will have a significant impact on cost. 

TPO vs SPF: Who wins?

The key takeaways are:

  • TPO is slightly cheaper initially.
  • SPF provides better insulation enhancing the life cycle cost of the system
  • SPF can be applied 50% faster
  • SPF is better on tectum (no penetrations)



Want to learn more about spray foam roofing for your school? Read our complete guide below:


Your School's Guide to Spray Foam Roofing

Author: Greg Palya

Greg Palya is the Digital Content Manager of West Roofing Systems, Inc. He has a B.S. in Marketing from the University of Akron and an MBA in Marketing from Walsh University. When he’s not trying to increase website traffic, you can find him on the basketball court or golf course.
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