Spray polyurethane foam roofing

Spray Polyurethane Foam Roofing

Despite the fact that few commercial roofing materials have the longevity and performance of spray polyurethane foam (SPF), few are as impressive as spray polyurethane foam (SPF). In the field of energy efficiency and interior comfort, spray foam roofing systems are one of the best solutions. The insulating and waterproofing properties of SPF make it a perfect choice for commercial roofing.

In this comprehensive guide, we tackle a variety of topics surrounding this multifaceted material to help facility managers and property owners understand what SPF is and how it works.

What Is Spray Polyurethane Foam?

In order to create a spray polyurethane foam roofing membrane, two chemicals are mixed with heat and pressure to form a solid, lightweight, and well-adhered roof surface. One of the components, Isocyanate (A), reacts heavily with polyol (B), which creates a flexible, lightweight, and highly adherent coating.

Despite the fact that spray foam has been around for quite some time, most facility managers and property owners are still relatively unaware of it. In spite of the fact that SPF has been used in various industries and applications since the 1940s, it wasn’t until the late 1970s that it started being used for its superior insulation properties in roofing and building construction.

Modern spray polyurethane foam roofing materials come in open-cell and closed-cell grades. Closed-cell foam is primarily used in commercial roofing applications, while open-cell foam is typically used for interior insulation and soundproofing.

The basics of roofing

SPF roofing uses a specialized spray foam rig to blend the A and B components of SPF and apply them directly on site. The two chemicals, which are housed in separate containers, are pumped through high-pressure hoses to a mixing gun at a temperature of 115-130°F through high-pressure hoses. It is imperative that the installation procedure is carried out in accordance with the appropriate heat and pressure to ensure a successful application.

It is important to understand that SPF provides the highest R-value (the measure of thermal resistance in any roofing material) of any commercial roofing material and is suitable for use in almost every type of climate. As the foam cures, it solidifies to form a durable, seamless, lightweight, and waterproof membrane.

This video demonstrates how spray foam is applied to a variety of different types of roofing substrates by installers.

Foam Density

To be strong enough for use in a commercial roofing application, the foam must have a density of at least 5 pounds per square inch (psi) to be dense. This component is the B component. It is generally assumed that the foam should have a density between 2.7 and 0 pounds to be rigid enough to walk on. Anything below that density would be too soft to walk on.

There is a problem with the foam not being able to withstand walking on it without damaging it.

UV Performance

There is no doubt that SPF is an excellent water proofer and an excellent insulator, but it does not provide much UV protection against the sunlight. It is necessary to coat the foam with an elastomeric roof coating (e.g., silicone, acrylic, urethane, butyl rubber) to achieve the necessary level of UV protection to be able to combat this problem.

Finding the Right Contractor

The process of installing a SPF roofing system requires specialized application equipment, a high level of understanding of SPF chemistry, and a lot of experience in the use of SPF chemistry. For some contractors, the process of becoming proficient at installing an SPF roofing system can take months or even years.

For those considering an SPF roofing system, take the time to properly vet potential contractors. Request to see job references, industry certifications, product samples, case studies, etc. In some cases, a contractor may be able to arrange a roof walk on a project they recently installed.

Based on SPFA guidelines, we recommend a minimum of 20 mils of silicone coating. In certain cases, as much as 40 mils may be required—depending on the chemistry used and warranty requirements. Visit www.sprayfoam.org for more information on the application of SPF and roof coatings.

What is the best roof coating for your home? Here is some information to help you decide.

The advantages of spray foam roofing

In comparison to conventional roofing materials, spray foam roofing insulation has the highest R-value. R-values are a measure of a material’s resistance to heat transfer. A higher R-value means that the insulation is more effective. SPF roofing grade has an R-value of approximately 5 per inch. However, it is widely believed that it provides much greater insulation qualities than the R-value implies.

Strength & Durability

Spray foam systems provide commercial roofs with an incredibly strong, yet remarkably lightweight, protective membrane. In fact, SPF systems, applied at a thickness of 1 inch or greater, are proven to enhance a building’s structural integrity.


A properly installed and maintained SPF roofing system can last 30 to 40 years, if not longer. SPF systems must be recoated every 10 to 15 years to ensure the long-term performance of the system by not allowing the sun’s UV radiation to degrade the foam layer.

Seamless & Self-Flashing

Unlike conventional roofing systems, spray foam roofs are completely seamless and self-flashing. SPF is specially designed to conform and adhere to irregular shapes and surfaces. These qualities virtually eliminate the ability for water to enter sensitive areas of the roof such as seams, fasteners, penetrations, and other flashing details.

Maintaining a Color bond roof is fairly easy. One needs to conduct Preventive maintenance of gutters, Aluminum windows in Wagga, and downpipes from time to time. One can inspect the roof for any leaks or signs of wear and tear on a regular basis. Repair work can be done in cases where the requirement is felt.

However, we highly recommend consulting with a professional spray foam roofing contractor to conduct regular roof maintenance inspections as part of a regular roof maintenance schedule to ensure that the roof is in good condition.

Quickly Installed

Compared to most other conventional roofing materials, SPF systems can be installed more quickly and are far less disruptive to building occupants. That’s because spray foam systems are applied directly to roof substrates and don’t typically require the removal of any existing roofing material.

Renewable & Sustainable

As SPF roofing systems are reusable, they produce little to no waste over the course of their lifespan, which helps to offset the concerns about landfill waste that normally accompany roof tear-offs and roof replacements, as well as the high costs associated with such an endeavor.

The materials that comprise spray foam roofing systems are also environmentally friendly.

The Disadvantages of Spray Foam Roofing

The application equipment for SPF materials is very expensive. While most roof coating spray rigs cost $10,000–$20,000, a spray foam rig—which includes an air compressor, generator, and enclosed trailer—can cost upwards of $100,000. Constant maintenance is also needed, and the parts can be difficult to access quickly when issues arise.

It is important to note that although Spray Works Equipment has no obligation to sell or maintain spray foam equipment, we do recommend it to contractors looking for spray foam solutions to offer their customers.

Effective UV exposure

The primary cause for spray foam system failures is UV exposure. Though SPF is an incredibly sturdy material, it is not designed to withstand prolonged exposure to the sun. This issue usually results from poor installation or lack of maintenance. Routine service and recoating the foam layer every 10 to 15 years are the only sure-fire ways to avoid premature system failure.

The cost of spray foam roofs is comparable with that of many other commercial roofing systems, however, they are much more expensive than regular roofing coatings. In addition to the roof size and the thickness of the SPF material required, there are a number of other factors to consider when choosing a SPF system. It is possible to expect to pay between $00 and $00 per square foot, or more, depending on the size of the roof and the thickness of the application.

Working with contractors

It is important to understand that not all contractors are equal when it comes to installing spray foam roofing insulation. For spray polyurethane foam to be effective, you need to possess a high degree of product knowledge and possess sophisticated application equipment and techniques to accomplish the job. In order to ensure that you find a qualified SPF roofing contractor, it is essential to practice due diligence when considering a SPF roofing system.

Overspray Potential

There is always going to be the potential for overspray when spray applying foam. One of the greatest strengths of SPF is its adhesive qualities. While that’s good for the roof, it’s not good for other surfaces that it may encounter nearby (e.g., automobiles, neighbouring structures, landscaping).

A contractor will use a wind shield to reduce the chance of overspray if the wind blows harder than 10-15 mph on a windy day. If the wind blows harder than 10–15 mph, then contractors will use spray foam that can travel very long distances.

Spray Foam Roofing Cost

As previously mentioned, spray foam roofing costs anywhere from $5.00 to $8.00 per square foot. These figures depend mostly on the thickness of the foam and the size/complexity of the roof structure. There are also other factors to consider such as location, condition of the existing roof substrate, top coating material, type of warranty, etc.

It’s worth mentioning that SPF systems are proven to significantly reduce a building’s energy cost, thus providing a much faster return on investment.

Tile roof substrates

Insulation foam is one of the most versatile materials available for insulation of commercial roofs, and it can be used on a variety of roof substrates, including:

  • Built-up roofing
  • Modified bitumen
  • EPDM (with cover board)
  • PVC (with cover board)
  • TPO (with cover board)
  • Metal
  • Concrete

The type of roofing substrate is not as important as its condition. At a certain point, commercial roofs can exceed the window for which an SPF system is an appropriate solution. We strongly recommend an infrared survey be performed on most substrates to ensure the roofing assembly isn’t too saturated.

SPF Roofing Installation Process

For an average size commercial roof (20,000 sq. ft.), the time needed for contractors to install a spray foam system is about 2 weeks—weather permitting. Generally speaking, the installation process can be broken down into four basic steps:

1. Surface Preparation

A pressure washer is used to clean the existing roof substrate to remove any dirt, dust, debris, or other foreign particles that might prevent adequate adhesion of the foam to the underlying material. Some cases, a primer may be needed to ensure proper adhesion of the foam to the underlying material.

Click here to speak with an American WeatherStar technical services representative about the proper adhesion of roofing spray foam, if you would like to know more about how it works.

2. Spray Polyurethane Foam

It can also be used to create a slope around certain areas of the roof in order to ensure positive drainage around specific areas of the roof. Spray polyurethane foam is next applied to the roof surface at a minimum thickness of 1 inch, though it can also be applied at greater thicknesses in order to increase the insulation value.

3. Elastomeric Roof Coating

Atop the SPF roof system, an elastomeric roof coating should be applied to prevent UV degradation, which will prevent deterioration due to ultraviolet light. The coating needs to be applied in multiple passes so that the mil thickness and coverage are uniform.

The most common type of coating used for SPF systems on steep-slope roofs is acrylic coatings. For flat (low slope) roofs, silicones or urethanes are preferable due to their ability to resist ponding water when they are applied to the flat roof surface.

4. Roofing Granules

Finally, #11-grade roofing granules are broadcast into the elastomeric top coat. This gives the system added strength, durability, UV protection, and resistance to wildlife. American WeatherStar requires the addition of roofing granules to SPF systems in order to qualify for an NDL warranty.

During the installation of the American WeatherStar system, American WeatherStar Approved Contractors are required to follow specific Application Guidelines in order to ensure quality and consistency standards. It is the responsibility of the installers to provide step-by-step instructions on how to install a system over a particular roof substrate.

Maintaining a foam roof

Committing to a routine maintenance plan is a good strategy for any commercial roof. For spray foam roof systems, it’s especially important. Although spray foam is a highly durable substance, it’s rather susceptible to damage from hail, accidental punctures, wind-driven debris, pedestrian traffic, etc.

In order to ensure a long-term success of any roof maintenance program, small problems must be detected before they become large problems.

A spray polyurethane foam contract will eventually burn away if it is exposed to the sun for too long and will eventually need to be replaced with new materials or worse yet will need to be repaired all together. If not addressed, the foam membrane will deteriorate and will require much more extensive repair or worse still, a complete system failure will occur.

The best time to perform maintenance on an SPF roof is in the spring and fall. This enables the system to be better prepared for the severe weather that normally accompanies the summer and winter months.

It is also recommended to conduct impromptu inspections immediately following significant weather events to ensure the foam and coating membranes remain intact.

Note: If a service contractor, specifically an HVAC Technician, needs to access and walk on a spray foam coated roof, take precautions to avoid unintended damage. Something as simple as a dropped tool or piece of equipment can easily puncture both the foam and coating membranes. If possible, arrange for a spray foam roofing contractor to survey the roof surface immediately following service appointments where roof access is required.

Fixing an aluminum roof

If you want to check the condition of the foam layer on an SPF roof, then it is essential to consult with a specialist to ensure that it hasn’t been compromised in any way. It is imperative to ask for assistance from a specialist if you suspect that the foam layer has been compromised in any way.

For minor damage, application of a roofing-grade mastic or sealant is usually all that is needed. These products are specially designed to bridge gaps and fill holes. It’s important to use the correct type of product when repairing a spray foam system. For SPF roofs with a silicone top coat, only a silicone-based mastic or sealant will provide the right level of adhesion.

In cases of severe damage, in which the foam membrane has become UV-damaged or saturated, more extensive repair methods are needed. Any damaged foam must be removed with a scarify grinder in order to reach uncontaminated foam. These areas are then primed to ensure the new foam application (minimum of 1 inch) will stick to the existing foam membrane.

Once the damaged areas of spray foam are corrected, multiple coats of an elastomeric roof coating are applied. Roofing granules are then broadcast into the top coat for added UV protection and durability.

Recoating a Spray Foam Roof

In order to achieve that kind of longevity, spray foam roofs have to undergo recoating every 10–15 years depending on the type of coating and mil thickness applied to the system in order for it to last 30 years or more. If properly installed and maintained, spray foam roofs can last up to 30 years or more.

The SPF recoat process includes:

  • Repairing any UV-damaged and/or saturated foam
  • Cleaning the entire roof to remove dirt, dust, debris, and other foreign contaminants
  • Priming to ensure proper adhesion (if necessary)
  • Applying additional coats of the same chemistry originally usedFoam-Gard (SPF + Roof Coating System)

Foam-Gard is a premium spray polyurethane foam roofing system exclusively from American Weather Star. It’s designed to restore and protect a variety of commercial roof substrates and comes backed with 10, 15, and 20-year Material or NDL (no dollar limit) System warranty options. Foam-Gard also has numerous industry approvals including FM, UL, Miami-Dade, and Florida Product Approval.


Without a doubt, spray polyurethane foam is one of the most impressive materials available in modern commercial roofing. SPF possesses many qualities that simply cannot be matched by other conventional roofing materials. With proper installation and routine maintenance, a spray foam roofing system may be the last roof you need to buy for your commercial facility.

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