Pros and Cons of SPF

Pros and Cons of Spray Polyurethane Foam (SPF) Roofing Systems

We all want more “bang for our buck” in today’s economy.  So, why should your commercial roofing system be any different?

SPF Roof on School

SPF Roof on School

While the choice is ultimately up to the building owner, we want to point out a few pros and cons to Spray Polyurethane Foam (SPF) Roofing Systems.

At West Roofing Systems, we’ve been installing spray foam roofs since 1979, so we’ve been around the block with everything spray foam related.

In this article, we’ll share what we know about the pros of spray foam roofs, but also all the cons. The goal of this article is to help you decide if a spray foam roof is the right choice for your building.

Let’s begin.

Pros of SPF Roofing

Easy Installation

The ease of installation can save you time and money with your new SPF roof. The application of the foam and coating is quick and can be applied with usually no interruption to the daily routine of the facility.

Spray Polyurethane Foam Application

Spray Polyurethane Foam Application

SPF roofs are installed by spraying a liquid on the existing roof and allowing it to expand into a foam.

This process means that the foam can conform to all roof shapes and types, even irregularly shaped roofs.

After cleaning the existing roof, the SPF roof can be applied directly over asphalt, shingles, concrete, metal and wood.

Energy Efficient

SPF roofing delivers thermal, air, and moisture barriers to provide the highest R-value per inch, which means the material provides better insulation for the building.

The polyurethane foam keeps heat out in the summer and in during the winter, lowering energy costs for facility owners. The silicone top coating resists UV light, protecting the foam and reduces heat absorption (emissivity).

Easy Maintenance

Once an SPF roof is installed, it requires minimal preventative maintenance and repair. If properly maintained, your SPF roof can last over 50 years.

SPF roofing systems should be inspected semi-annually, in the Spring and again in the Fall. Additional inspections are also suggested following any event that might have caused damage to the system.

In the event where a silicone recoating is needed, there’s no tear-off of the existing materials; you apply the new coat on top of the current system.

Seamless and Waterproof


Seamless SPF Roof

Seamless SPF Roof

Seams and penetrations are the primary sources of leaks in roof systems, SPF eliminates this vulnerability.  Since the SPF mixture is applied as a liquid, it can fill gaps, seams, and cracks in the existing roof and substrate.

The application of the polyurethane foam allows the contractor to level out the roof to decrease the chance of ponding water. The foam material can expand and contract with the building in accordance with outside temperatures, reducing the likelihood of cracks and splitting.

Renewable and Sustainable Roofing

SPF roofs create little to no waste during its lifetime. In most cases, there is minimal stripping of the original roof, and the SPF roof is installed on top – eliminating the need for costly roof tear-offs and waste.

The materials that are used for SPF roofing systems are also environmentally friendly:

  • Zero Ozone Depleting Potential (ODP)
  • Low in the Emission of Volatile Organic Compounds (VOCS)
  • Free from Chlorofluorocarbons (CFCS)
  • Ultra-Low Global Warming Potential (GWP)

Learn Spray Foam Quickly. Download "The Spray Foam Roofing Cheat Sheet"

Cons of SPF Roofs

Not All Contractors are Created Equally


SPFA Certifications

SPFA Certifications

The application of the spray foam is a process that needs to be done correctly from the beginning. The contractor needs to be precise with the application and have a solid understanding of the chemicals they are using.

It doesn’t take a large crew to install an SPF roofing system, but it requires a high degree of technical knowledge and experience.

The Spray Polyurethane Foam Alliance (SPFA) has an ISO-17024 compliant certification program that has multiple levels, requires the contractor to pass an exam and meet the criteria for a certification.

If the roofing system is installed incorrectly, it can be detrimental to the lifespan of the roof and underlying substrate.

Limited Installation Window

SPF can only be sprayed during specific weather conditions. Installation of an SPF roofing system cannot be performed when there is ice, frost, surface moisture, or visible dampness on the existing roof.

While the installation does not interrupt the daily functions of the building, the weather requirements can leave only a small window of opportunity.

Overspray Potential


Spray Polyurethane Foam Application Team

Spray Polyurethane Foam Application Team

Since the SPF roof is installed by a spray application, there is a risk of the wind carrying overspray onto surrounding cars and other surfaces. While this does not pose a health concern, it is a concern for surrounding property.

At West Roofing Systems, we take extra care to prevent overspray. We have a few different techniques that we practice to protect surrounding property.


SPF roofing systems should be inspected twice a year whether there is known damage or not. And especially after weather events that could cause damage: such as hail storms, tornados, and hurricanes. Small cracks, gouges, or punctures can be repaired with an elastomeric sealant compatible with the SPF system. So you need to keep your SPF roof in mind at all times.

Accurate Repairs Needed

SPF does not have as high of resistance to punctures or damage. If your SPF roof is damaged, you must call an SPF contractor to perform the repair. The repair needs to be made with silicone because typical roofing repair materials do not adhere to the silicone coating.

Spray Polyurethane Foam Roofing Systems are becoming the go-to roofing for commercial, industrial, and manufacturing facilities that are looking for a sustainable, economically efficient option.

At West Roofing Systems, our goal is to get you a long lasting, durable roof that will protect your facility. That includes working with our award-winning team to choose the best roofing systems to meet your needs.

Want to Learn More About Spray Foam Roofing?

Download our free guide below which includes:

  • How much a spray foam roof costs?
  • Common problems spray foam roofs have?
  • What are the benefits of a spray foam roof?

The spray foam roofing cheat sheet - download now

Author: Rufus West

Rufus West is a commercial roofing expert! You may see him on the West Roofing website and also on the West Roofing social media pages, giving fun facts and tips about the company and roofing industry.

Just like West Roofing System’s roof solutions, he isn’t bothered by water—it simply rolls off of his back!

  • Emma Hallberg

    at Reply

    Hi, can SPF roof be installed on a sloped roof? Thanks

  • Jerry

    at Reply

    Can ravens and other birdspeck holes in the roof?

    • Aubrey Barto

      at Reply

      Early Spray Polyurethane Foam roof designs were susceptible to occasional mechanical damage by birds (crows and seagulls). This phenomenon has been stopped with the inclusion of granule surfacing embedded into the top coat.

  • Vijay g

    at Reply

    Can it be used for computer server room roof insulation

    • Aubrey Barto

      at Reply

      Yes! That is a great use for SPF Roofing.

  • Yoko Olsgaard

    at Reply

    We have squirrels that like to jump off tree branches and run marathons on our Eichler style home. How do SPF roofs perform under daily squirrel runs?

    • Unless they’re radioactive 50 lb. squirrels, I don’t see where squirrel traffic will be a major problem. As with any roof though, it’s always a good idea to enter into a maintenance program to ensure that all is well on the roof. Building/home owners tend to forget about the roof, out of sight out of mind kind of mentality. Having a professional make yearly inspections is a good idea

  • Janet Surkin

    at Reply

    Can this material be used if there are vents and HVAC equipment on the roof?

    • Hi Janet, yes. you can spray foam on roofs that have vents and HVAC equipment. We will close those off during application, but once that’s done, we’ll open them back up and you’ll be good to go.

  • Gene

    at Reply

    Can a foam roof be applied on top of a built up roof after the gravel is removed or should the gravel and/or the built up system be removed first?
    Once the foam roof is installed is it coated with a silicone coating?
    Roughly how much does it cost per square foot to install a foam roof system?

    • The dirt and loose gravel needs to be removed first, typically with a hydro-vacuum process (vac truck), also need to verify that the existing roof assembly is dry and there is only 1 roof in place (building code only allows for 2 roofs in place at one time). Ultimately, once cleaned and prepped, and verified that the roof is dry, a gravel built up roof is a very ideal surface to apply foam to.

      Yes. A spray foam roof is always coated, usually w/silicone.

      Spray foam roofing usually cost between $4-$7 per sq. ft.

  • pattie

    at Reply

    What areas of the country – weather zones – can this roof be used? What is the R-value of the roof? Can it be installed over rubber roof? Can it be installed over modified bitumen roll roofing? Does your estimate of $4-7/ sf include the silicone layer? How often does the silicone layer have to be reapplied?

  • Kusum Shekhlia

    at Reply

    What is the effective useful life of this product?

    • A spray foam roof can be the last roofing system you’ll ever need on a building. Since a spray foam system consists of spray foam, coating, and granules, after 10-20 years, some of the coating and granules will naturally wear away. At year 10-20, a contractor will add more coating and granules. The foam never gets touched and never loses R-value. Spray foam is sustainable and renewable. Hopefully this helps!

  • can it be installed over a tpo roof?

  • tom naraghi

    at Reply

    can you spray this stuff on flat concrete roof to make the needed 1/4 per foot of slope to go from 1.5″ to 4″ of total slope

    • Hi Tom. Yes! With spray foam being “spray-applied”, the slope can be customized to fit the needs of your roof. Thanks!

  • steven reeves

    at Reply

    I have a ballasted EPDM roof, if the rock is removed and the EPDM is cleaned and foam sprayed is this enough weight to stop the insulation for bumping up.

    • Hi Steven, since the ballasted EPDM roof is no longer fully-adhered with the rock being removed, a cover board needs to installed before spray foam can be installed. This should stop the existing insulation from bumping up. Hope this helps!

  • kaye Shurman

    at Reply

    Do the silicone coatings come in different colors or only white?
    Are foam roofs fire resistant?

    • Hi Kaye! The silicone coatings come in different colors. Some want the coating color to match their building, so we’ve done an assortment of different colors. But most choose white for the reflectivity of the sun. And yes, spray foam roofs are fire resistant. Thanks!

  • Marc Dick

    at Reply

    Please explain how SPF is “sustainable and renewable”?

    • Hi Mark, say you get an SPF roof with a 20-year warranty. For R-value purposes, you need 1.5 inches of SPF. On day 1, your roof would get 1.5 inches of foam and 30 mils of coating to protect the roof. After 20 years, the 30 mils of protective coating would naturally wear away to 7-8 mils. Now a contractor can clean the roof, and add more coating to bring the level of coating back to 30 mils. This would grant you a new 20-year warranty. The foam is never touched and it doesn’t lose any of its insulating properties. The “recoat” process can be repeated over and over again. Hope this helps!

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