Why Enverge Nexseal LE Closed Cell Is Safer

It’s easy to assume that spray foam products are pretty much the same, irrespective of brand and manufacturer. This isn’t correct and there can be distinct differences between the performance of different brands of spray foam in terms of the chemical formulation and processing parameters. Our business has been built upon safety and comfort for the end user and the spray foam installer which is why we delve a little deeper into how Enverge Nexseal LE Closed Cell Foam stands out from some of its competitors.

What Is Closed Cell Foam? 

Closed Cell Spray Foam Insulation is a two-part system that incorporates a 50:50 ratio of Polyol and Isocyanate to create a 2-pound density, rigid insulation. Closed Cell Foam is spray-applied using specific machinery as found in our article “What Equipment Is Used To Make Spray Foam?” The density of closed cell spray foam insulation is comparable to that of rigid PIR insulation boards that are commonly used to insulate new and existing buildings and the chemical formulation is similar in that both products are Polyurethane-based. 

Compared to the alternative of Open Cell Foam, Closed Cell is denser, has a lower thermal conductivity and provides one of the best insulating performances per inch, making it an attractive proposition for new and existing buildings. As the drive towards Net Zero continues, Closed Cell is becoming one of the fastest growing insulation materials in Europe, America and Asia thanks to its long-term and durable performance. In some instances, Closed Cell Foam can be used to encapsulate asbestos, eliminate surface condensation and strengthen failing roof substrates such is its versatility and suitability in almost any environment.

What Is Enverge Nexseal LE?

Enverge Nexseal LE is our proprietary closed cell spray foam product that has been tested to UKAS standards and has achieved BBA Certification for Pitched Roof, Walls and Suspended Floor installations. It is also suitable for use in many industrial and commercial environments as well as new-build and retro-fit homes. Manufactured by our partner, Holcim-owned Enverge, Nexseal LE has been developed over a number of years to become one of the most trustworthy and safest closed cell foams on the planet, thanks to its low exothermic reaction when installed! Formulated using HFC blowing agents and containing no harmful VOCs or HFCs, Nexseal LE is environmentally sustainable, uses recycled materials and has a low global warming potential of just 1.

What Does Low Exothermic Mean?

The “LE” after Enverge Nexseal stands for Low Exotherm which relates to the reaction temperature and heat released by the chemical during the spraying process. A low exothermic reaction is a chemical reaction that releases a relatively small amount of heat energy. Exothermic reactions are those that release energy in the form of heat as they proceed, and the term “low exothermic” indicates that the heat released is not substantial. In other words, the temperature of the reaction mixture may increase, but the increase is not significant or potentially dangerous.

Exothermic reactions typically involve the formation of chemical bonds that are more stable than the bonds in the reactants, and the excess energy is released as heat. The extent of heat released in an exothermic reaction can vary widely, depending on the specific reaction and the reactants involved. Some exothermic reactions release a large amount of heat, while others release only a small amount.

What Can Happen With A High Exothermic Foam?

Generally, closed cell foams should not be spray-applied in layers of more than 25-50mm because they aren’t formulated to provide a low exothermic reaction and instead, hold a lot of heat within the insulation during the expansion and curing process. When this heat is released, the foam can crack and shrink back if sprayed too thickly without leaving ample time for cooling between layers. The cracking and shrinking process may not happen instantly and could occur over several days or even weeks. In addition, when closed cell spray foam is installed in layers that are thicker than the manufacturers recommendations, it could char and even combust in some circumstances! This shouldn’t deter from using the product, it’s just important to choose a spray foam installer that is experienced, holds manufacturers approval and has ideally been assessed as a BBA-Approved Installer.

Cheaper Spray Foam Systems

We’ve seen a gradual increase of spray foam materials coming across from Eastern Europe and the Middle East. Some of these systems are manufactured in accordance with European testing standards whereas others aren’t. Importantly, many of these brands have not been tested or certified by the BBA or KIWA to UKAS standards. This can pose a significant threat to UK spray foam industry, particularly if the installer or end users base their decisions wholly on the price of the material. Cheaper, unregulated foams can always outcompete products like Enverge Nexseal LE when it comes to price but when considering safety, yield and performance, there is the potential that these products can cause damage to buildings when sprayed too thick, too quick. This is why our products are tested for their dimensional and mechanical stability to ensure that they can be used in accordance with the correct parameters in the right environments.

See our gallery images below to show what can happen when the wrong type of closed cell foam is used or the installer pushes the processing parameters beyond the manufacturers recommended guidelines.


So How Is Enverge Nexseal LE Safer?

Unlike many other brands of closed cell spray foam insulation, Enverge Nexseal LE can be applied in layers of up to 100mm. This helps to provide the end user with reassurance that the foam will not crack, shrink, char or combust, especially if it’s being covered over with plasterboard. For the installer, the job can be completed faster without the need for many different layers of foam and this can also benefit the project itself by speeding up the installation process. The low exothermic reaction helps to release any heat from the foam quickly during the expansion process and vastly reduces the opportunity for heat to be trapped within the layers. Although professional spray foam installers will follow manufacturers guidance to ensure that any brand of foam is installed correctly, Enverge Nexseal LE is simply a more forgiving and safer foam when pushed to the limits.

Check out our video below to show how Enverge Nexseal LE is sprayed thickly and quickly with a smooth, even rise to provide a safe, monolithic and airtight thermal layer of closed cell insulation.


In conclusion, whether you are the end user of spray foam insulation or the installer, you want to work with materials that provide the best end result. For end users, Enverge Nexseal LE is the safer choice thanks to the low exothermic reaction of the product during the installation process. This ensures that the risks of the closed cell foam cracking, shrinking, charring or combusting is extremely low when compared with some other brands of spray foam insulation. For the installer, Enverge Nexseal LE can be installed quickly and efficiency thanks to its ability to be sprayed at up to 100mm per layer. Where many other brands of closed cell foam are limited to 25-50mm per layer, Enverge Nexseal LE enables the installer to confidently apply the foam in thicker layers to achieve the desired outcome in less time. Many spray foam installers are converting to Enverge Nexseal LE for peace of mind and better outcomes for their customers. 

Despite what some people may say, there are distinct differences between the performance of spray foams depending on who they are manufactured by and where in the world they are manufactured. Enverge Nexseal LE is priced accordingly thanks to its high yield per set, ease of install and ultimate safety for the installer and end user.