R&A University

Updates, news, and information to educate and empower owners.

How Spray Polyurethane Foam (SPF) Strengthens Commercial Structures

1 May 2017 | Under SPF Insulation | Posted by | 0 Comments

What’s the strongest part of a commercial building?


The load-bearing walls of a commercial building structure are the strongest parts of the building, no question. They withstand the constant weight of the roof as well as lateral forces created by gravity and external forces (like wind and other forces). The effect of wind on commercial building walls is what’s often referred to as a ‘shearing force’. (You can read more about the shear force of walls here.)

One of the more common collapse points of a commercial building is an exterior wall. When the weight of the roof or an external force impact causes an unbearable amount of pressure, the supporting wall collapses to relieve the weight. Commercial roofs often bear the tensile strength of material stretched across a span of distance, such as a truss or roofing panel. Even with sturdy walls supporting the roof, a section of roof can still give way and let excess weight, ice, or snow collapse into a building’s interior.

What if we could reinforce the entire structure of your commercial building in one simple solution? If it seems too good to be true, let us reassure you: SPF, spray foam roofing, is the magic fix for strengthening commercial buildings.

What is Spray Foam?

In case the name didn’t give it away, spray foam is a liquid-based compound that is sprayed into place that expands into a foam. Of course, that’s an overly simple way of describing spray foam. Spray polyurethane foam is a dual-compound insulation type. Let’s start with the two parts that make up one of our most popular spray foams, the FOAM-LOK 2000 Closed-Cell Spray Foam from Lapolla Industries:

  • Part A: Isocyanate – The technical type of isocyanate used in many spray foams is Methylene Diphenyl Diisocyanate. The purpose of isocyanate is that it adds rigid strength and surface protection to the spray foam. We take great care to ensure our team is protected with the proper safety equipment to prevent any health hazards that may occur from exposure to Methylene Diphenyl Diisocyanate during application.
  • Part B: Polyol blend – This is where the spray foam gets its flexibility for installation and adhesion. The Polyol is a blend of materials that give dexterity and expansive abilities to the foam. Lapolla Industries creates its proprietary polyol blend for its products.

Note: any potential health risks posed by Methylene Diphenyl Diisocyanate only occur during application and within the first hour following application. We strictly adhere to Lapolla Industries and OSHA’s recommended health and safety guidelines to protect our installation team’s short-term and long-term health.

How Does Spray Foam Work?

The isocyanate and polyol blend chemicals are stored, transported, and prepped for application in large, commercial-grade chemical drums. A series of hoses are connected to each chemical drum and then connected to a spray applicator. The hoses are activated and draw the two chemicals into the spray applicator. As soon as the chemicals are fed into the mixing nozzle, it starts an immediate chemical reaction.

The now dual-compound is sprayed into place and the chemical reaction results in a rapid expansion process. Spray foam can expand to as much as thirty times its liquid density! A vast majority of spray foams used in commercial applications are ‘closed-cell’ spray foams. Why is this important and what makes a spray foam closed-cell versus open-cell?

Closed-cell spray foam occurs when gas molecules are trapped inside the spray foam during the expansion process. When open-cell spray foam is applied, the foam traps pockets of air, not gas, inside the foam material. Since gas is denser than air, the closed-cell spray foam is naturally stronger and more durable than open-cell spray foam.

Does spray foam reinforce a commercial building’s structure strength?

In a word, absolutely! How is that possible? As the spray foam expands, it also adheres to virtually any substrate that it comes into contact. As the foam expands, tens of thousands of contact points are connected to the spray foam. Because the spray foam is liquid in nature during application, it also permeates and seals off virtually any opening in the contact surface, including large cracks and holes.

This means the spray foam itself is actually as a self-sealing reinforcement of the building structure. As soon as the foam finishes expanding, it starts hardening. Within a matter of ten minutes, the spray foam is already capable of sustaining up to 90% of its final tensile strength capability. What does that mean for the building structure? As the foam hardens, it naturally bonds with any structure element that it contacts.

Think of spray foam as a type of glue holding together any part of your building connected to the foam. Since spray foam is seamless, it has unprecedented capability of contacting hard-to-reach building parts and bonding them with surrounding building elements.

Do you remember we talked about ‘shear force’ earlier? Let’s imagine a wall that has a metal exterior with steel studs on the inside. Depending on its exposure risk to high winds, that exterior wall may be susceptible to twisting and flexing in higher winds. This would cause extra pressure and tension on the metal paneling, namely on the panel’s fasteners and seals. With enough wind ‘shearing force’, the metal panel could easily tear away from the steel studs because of the excessive pressure placed on the panel’s fasteners.

Now, imagine that same metal exterior wall with steel studs that has spray foam applied on the inside of the wall between the studs. The spray foam bonds with both the metal paneling and the steel studs. The closed-cell construct traps stronger gas molecules inside the foam material that can withstand external twisting and tugging by the wind’s shearing force.

When higher winds now hit that wall, the spray foam provides a monolithic bond adhering the metal panel and steel studs together. Instead of a series of somewhat connected materials, you now have a single bonded metal wall that is braced against the shearing force.

Spray Foam Reinforces Commercial Roofs Against Wind Lift

What about commercial roofing? As with the exterior walls, spray foam is often used as a commercial cool roofing solution. BURs, metal roofs, and other commercial roofing systems can usually be left in place while spray foam is applied over them. The spray foam invades and seals off any openings in the existing commercial roofing system.

As the foam expands, it bonds to any of the existing roof material. This means your commercial roof transforms from a series of panels or planks into a single, seamless roofing surface.

What does that do to your roof’s tensile strength? It goes through the roof… figuratively. Since your roof is no longer a combination of pieces, it means there are virtually no openings for wind lift to make its effect. Wind lift occurs when a high-level of wind penetrates under the edge of a roof and ‘lifts’ the roof to separate it from its building structure.

Wind lift is most commonly experienced during extreme weather, such as tornadoes and hurricanes. The National Oceanic and Atmospheric Administration (NOAA) classifies Spray Polyurethane Foam as the most durable and resilient commercial roofing material currently available today. St. Louis is known for its high winds during spring and summer storms. It’s after these storms we see so many businesses searching for parts of their roofs and in need of our assistance.

Spray foam bonds with the existing roofing system as well as the building’s supporting structure, namely the walls. When high winds occur, the spray foam acts as a type of wind barrier that deflects the wind’s effect around the building. When Hurricane Katrina occurred in 2005, it was closed-cell spray foam that kept many building intact against historic levels of high winds. Hurricane Katrina registered some of the highest levels of hurricane activity ever recorded across the Gulf Coast region. As other buildings crumbled and caved, it was spray foam that helped save lives by keeping building intact until help arrived. Read more about closed-cell spray foam’s resiliency in the face of Hurricane Katrina.

Trust R&A Contracting to Reinforce Your Building With Spray Foam

Whether your building is brand-new or decades old, you can expect high winds and extra ice and snow to put more pressure on its performance. What are you doing now to reinforce your building against the extra workload?

Our R&A Contracting team works with business owners across St. Louis to provide exceptional spray foam solutions. We provide complimentary on-site inspections to identify potential problem areas for your building’s roof and walls. Choosing the right type of spray foam and installation strategy starts with knowing your budget and your building’s history of storms. We can put together a realistic plan of action that respects your budget and is in the best interest of your building.

The first step is scheduling your complimentary on-site inspection with our team. Save your spot on the schedule. We look forward to serving you and keeping your building healthy and strong for years to come!


Jim Lowry - Bissinger's Handcrafted Chocolatier


Jim Lowry - Bissinger's Handcrafted Chocolatier


Jay Moore, President of Safe Way Tire and Auto Center


Will from Dardenne Prairie, MO


Jerry from SLR Properties


Lindell from Greater Missouri Builders (GMB)


Ross from Troy, MO


Director of Facilities for a large Property Management Company


Will from O'Fallon, MO