spray foam roof at st stephens church in Sandusky, Ohio

What’s the Most Affordable Commercial Roofing System?

Greg PalyaSpray Polyurethane Foam Roofing

The most affordable commercial roofing system is decided by lots of factors. This includes the current conditions of the existing roof, lifetime costs, energy savings, etc.

In this article, you’ll learn that the most affordable commercial roofing system is:

  • The one that requires the least amount of tear-off to install
  • The one that’s installed the easiest
  • The one where the materials are available
  • The one that reduces future energy costs
  • The one that can be renewed for 33% – 50% of its initial installation cost

NOTE: the first three talk about “affordability today”, the last two talk about “affordability in the future”

And so you’re aware, we only write articles based on true events and experiences. Every piece of content written at West Roofing Systems is produced in-house. Every article is reviewed and edited by a roofer/salesman with 30+ years of experience in the field.

Let’s get started!

The most affordable commercial roofing system is the one that requires the least amount of tear-off to install

If you’re unaware of “tear-off”, it’s the labor required to remove a roofing system. An easy example is a single-ply roofing system (rubber sheets) that are ripped off the roof and transported to a landfill.

One of the best advantages of a spray foam roof is that tear-off is minimized. Only the saturated areas of a roof need to be removed before spray foam can be installed. *

This is different from metal, BUR, and single-ply roofing systems. These systems require the existing roof to be completely torn off before installing the new system.

Imagine you have a single-ply roof that’s at the end of its life. If you want to install a new single-ply roof, your best long-term solution would probably be to remove 100% of the old roof, remove and replace the saturated insulation, and install a new single-ply roof over the existing insulation.

If you wanted to go with a spray foam roof, you could remove the saturated insulation and install spray foam right over the existing roof. This is only if there’s only one roofing system in place.

*A commercial roof can only have two roofing systems installed. If two roof systems are already installed, at least one system needs to be completely torn off before a new roofing system is installed. This includes a spray foam roof.

Long story short: A roof tear-off is expensive and time-consuming. If you can choose a roofing solution that minimizes it, it will save you money.

spray foam roofing at west roofing systems
spray foam being installed over an existing granulated built-up roof

The most affordable commercial roofing system is the one that can be installed the easiest

This all has to do with time. The more time it takes to install a roofing system, the more expensive the project will be.

A penetration, such as HVAC units, skylights, pipes, drains…anything that comes through a roofing system, can increase the time for installation.

Penetrations on a roof interfere with metal and single-ply roofing systems. Since these systems are rolled out or pieced together, when an HVAC unit gets in the way, these systems require flashing materials with sealants which frequently result in leaks.

If a roof has hundreds of penetrations, this can greatly increase the time it takes to install a roof system.

However, two roofing systems are fluid-applied. Spray polyurethane foam (SPF) and silicone roof coating systems are both fluid-applied roofing systems.

When a penetration comes along, an installer simply sprays around it and continues going. There is no interruption of the installation.

Here’s a video of spray foam being installed around a penetration:

Long story short: Penetrations increase the time it takes to install non-fluid applied roofing systems. Time always equals money.

The most affordable commercial roofing system is the one where materials are available

As of December 2021, there is a shortage of polyiso board. Polyiso board is used as insulation for most commercial roofing systems.

A common commercial roof will have the deck, polyiso board, and then single-ply or metal on top.

Since polyiso board is no longer available (we’ve heard orders placed today might not come in until June 2022!), the price of available polyiso is going to be very expensive.

It’s simple supply and demand. No supply increases the demand.

Spray foam and roof coating systems don’t need polyiso board.

Spray polyurethane foam is a roofing membrane and insulation in one.

Chart, diagram

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Spray foam has an R-value of 6.5 per inch of thickness. With such a high R-value, there is no need to use another roofing insulation, such as polyiso board.

Roof coating systems don’t have any insulation. They are basically a super thick paint that’s engineered to withstand outside elements. These are usually installed over an existing roof. Roof coating systems cannot be used on their own as a roofing system.

For example, you cannot have a roof deck, and then add coating over top. This would provide your roof with no insulation. Roof coating systems are best used on existing roofs where insulation is in good shape (not a lot of saturation) and the membrane is in decent shape. This is to reinvigorate the roof and get it under a new warranty.

A perfect candidate for a roof coating system is a roof where:

  • 25% or less of the roof’s insulation is wet
  • The seams of the roof are in decent shape
  • There’s been at least annual routine maintenance

Long story short: Polyiso board isn’t available. To minimize cost and get your roofing project completed, it’s beneficial to look into other roofing systems.

The most affordable commercial roofing system is the one that reduces future energy costs

Spray foam roof at Mercer County Career Center in Mercer, PA
completed spray foam roof at Mercer County Career Center

Most of the time when we talk about affordability, we’re talking about now…at this moment. But since a roof lasts a long, long time, the costs over the lifetime of the roof should be calculated.

If a roof increased your R-value, which lowered your energy bills every month, wouldn’t that lower the lifetime cost of that roofing system?

That’s exactly what a spray polyurethane foam roof does.

Spray foam has the BEST R-value of any roofing system out there. Here are the R-values (per inch of thickness) of other roofing insulations:

  • Spray foam: 6.5
  • XPS: 5.0
  • EPS: 3.6 – 4.2
  • Polyiso: 5.5

NOTE: Metal and single-ply roofing systems use XPS, EPS, or Polyiso board.

And spray foam’s R-value doesn’t decline or lose any performance over time as all the others do.

While it’s impossible to determine how much per month you’ll save on your energy bills by installing a spray foam roof, we know it’s going to be greater (assuming the same insulation thickness) than any other roofing system.

Here’s a popular story of Texas A&M University. They had multiple built-up roofs that were leaking. After installing the spray foam roofing system, they were saving so much money on their energy bills that it paid for the entire installation in 4.5 years!

The most affordable commercial roofing system is the one that can be renewed

What happens to metal, BUR, and single-ply roofs when their service life is over?

They need to be completely torn off and transported to a landfill.

A spray foam roof is different. It can be renewed over and over again.

Say you have a spray foam roof that has a 15-year warranty. In year 16, a contractor will clean the roof, make any spot repairs, and then add more coating onto a roof.

On the initial installation, the roof might’ve gotten 1.5 inches of foam that’s protected with 25 mils of coating.

Over 15 years, that coating will probably wear down to 7-8 mils.

A contractor will clean the roof and bring the 7-8 mils back to 25 mils. A new 15-year warranty can be granted.

The cost of a recoat is 1/2 to 1/3 of the initial installation. For example, a $100,000 spray foam roof can be renewed between $33,000 and $50,000.

Once a $100,000 single-ply roof’s life is over, it’ll most likely cost $100,000 (in today’s dollars) for another single-ply roof.


We know that most building owners or property managers have never heard of a spray foam roof before. Hopefully after today, you learned that spray foam is the most affordable roofing system today and will be for the lifetime of your building.

West Roofing Systems has been installing spray polyurethane foam roofing systems since 1979. Sometimes a spray foam roof is the best solution, sometimes doing a simple repair is the best solution. But it’s beneficial to get any roofing contractor on your roof ASAP if anything is going wrong.

Here are a few case studies of recent spray foam roofing projects.

Here are a few drone videos of recent spray foam roofing projects.

Below is the Spray Foam Roofing Cheat Sheet. It covers most of the basics of the roofing system (cost, problems, how it compares to other roofing systems, etc.)

The spray foam roofing cheat sheet - download now
About the 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 teach others about spray foam roofing and silicone roof coatings, you can find him on the basketball court or golf course.