spray foam roof at a school in Columbia Station, Ohio.JPG

Pros and Cons of Spray Foam Roofing Systems

In this article, you’ll learn the pros of spray foam roofing, such as:

  • Installation cost and lifetime cost
  • They are easy to install (reduces labor costs)
  • It has the highest R-value per inch of thickness
  • It’s easy to maintain
  • It’s seamless
  • They are environmentally-friendly
  • It has closed-cell properties (which means it won’t leak)
  • It’s renewable and sustainable

But nothing’s perfect. We’ll go through the cons as well, such as:

  • There are bad spray foam contractors out there
  • Overspray is a constant issue
  • And it needs to be at least 50 degrees to install

And so you’re aware, West Roofing Systems has been specializing in commercial spray foam roofing projects since 1979. We’ve seen the good, bad, and ugly when it comes to spray foam.

This article has been reviewed, edited, and approved for publishing by a spray foam roofing expert with more than 30 years of experience.

Let’s get started!

Pros of Spray Foam Roofing

Costs

As of August 2022, spray foam roofs costs around $8-$12 per square foot. Many variables influence the cost. The installation cost is in the ballpark of other traditional roofing systems.

Did you know spray foam can be installed over most existing roof systems? This can reduce tear-off costs. It’s also good for the environment as you aren’t contributing to landfills.

And since spray foam roofs can be recoated after their warranty expires, they are a better long-term cost play.

A foam roof can be recoated (or renewed) for 33% – 50% of the installation costs. On a traditional roof that needs to be torn off and replaced after the warranty expires, the cost is 100% of the installation cost.

Easy Installation

 
The ease of installation can save you time and money. The application of the foam and coating is quick. It can be applied with no interruption to the facility’s daily routine.

Spray Polyurethane Foam Application
Spray Polyurethane Foam Application

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

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

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

Energy Efficient

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

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

Easy Maintenance

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

Spray foam 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.

If 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

Seamless SPF Roof
Seamless SPF Roof

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

Applying 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 per outside temperatures, reducing the likelihood of cracks and splitting.

Traditional roofing systems need to cut the membrane, use adhesives, termination metal, screws, fasteners, etc. to make penetrations watertight. An example of a penetration is an HVAC unit, skylight, pipe, or anything that comes through the roof.

With spray foam being fluid-applied, none of those materials are needed. The foam is sprayed around the penetration, and it becomes watertight.

Watch this video in our training center on how foam can make a box (simulating a penetration) watertight by becoming a part of the flat roofing area:

Environmentally-Friendly

 

Spray foam roofs create little to no waste during their lifetime. In most cases, there is minimal stripping of the original roof, as only the wet and saturated areas are removed.

A spray foam roof is installed on top, eliminating the need for costly roof tear-offs and waste.

The materials that are used for spray foam 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)

Closed-cell properties

If a spray foam roof gets a cut, puncture, or hole, it will not leak. That’s because of the foam’s closed-cell structure. Water will sit in a hole and not move further south into the roofing system:

closed cell spray foam holds water in place

The opposite is true with polyiso board or other commonly used insulation wood types. These types of insulation have open-cell properties, which means the water can travel vertically and horizontally, saturating more roofing material.


Even if there’s a slight uplift (or puncture) in a single-ply’s membrane, if water can get into the insulation, it will travel and saturate more of the insulation. This can lead to a labor-intensive repair and water coming into your building.

Renewable and Sustainable

The spray foam roofing system has four parts:

four parts of a spray foam roofing system

The two coats on the spray foam roof will naturally wear away over time.


For example, on a spray foam roof with a 20-year warranty, a 30-mil thickness of the coating will be installed. In year 20, there will most likely be 7-8 mils of coating left.


A contractor can clean the roof, install a new 30-mil thickness of the coating, and you’ll get a new 20-year warranty.


This is how a spray foam roof can be renewed repeatedly. The spray foam is sustainable as it doesn’t lose any R-value or performance metrics over time.

Cons of Spray Foam Roofing

There are bad spray foam roofing contractors

Applying spray foam is a process that needs to be done correctly from the beginning. The contractor needs to be precise with the application and understand its chemicals.

It doesn’t take a large crew to install a spray foam roofing system. Still, 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 meets the criteria for certification.

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

Make sure you choose a contractor that has proven to install spray foam roofs that have lasted. They should have a list of foam roofs they’ve maintained and recoated.

Limited Installation Window

Spray foam can only be sprayed when it’s at least 50 degrees in Fahrenheit. Installation of a spray foam 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 spray foam 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’s a concern for the 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.

Conclusion

Now that you know the pros and cons of spray foam roofing, what about the pros and cons of all the other commercial roofing systems?

In the downloadable eBook below, we talk about the pros/cons of:

  • Single-ply
  • Metal
  • Shingles
  • Built-up roofs
  • Roof coating systems


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25 Comments
  • Emma Hallberg

    at

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

  • Jerry

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    Can ravens and other birdspeck holes in the roof?

    • Aubrey Barto

      at

      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

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    Can it be used for computer server room roof insulation

    • Aubrey Barto

      at

      Yes! That is a great use for SPF Roofing.

  • Yoko Olsgaard

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    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

    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

    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

    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

    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

    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

    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

    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

    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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