Closed-Cell Spray Foam and Scientifically Engineered Wall Systems: The Ideal Choice for Extreme Weather Protection

By Maxime Duzyk, Director of Building Science and Engineering at Huntsman Building Solutions
In the face of increasing extreme weather events such as heavy seasonal rainstorms and windstorms, the resilience of building structures is of paramount importance. Key to enhancing the structural integrity and energy efficiency of buildings are the air and vapour barrier systems, where closed-cell spray foam insulation emerges as a frontrunner in the suite of protective measures, offering robust protection against the elements.
Known for its compact and dense cellular structure, closed-cell spray foam expands and hardens from its liquid form into a solid foam to provide a high degree of thermal insulation and moisture resistance. Its rigid nature adds structural strength to the walls and roofs where it is applied, providing reinforcement to help buildings withstand the physical stresses imposed by high winds and heavy rainstorms, and reduce the likelihood of structural failure and wind uplift during severe weather events.
Closed-cell spray foam acts as an ideal air barrier because it creates a continuous insulation layer that fills gaps, cracks, and crevices in the building envelope. Once cured, it forms a rigid and dense material that is impermeable to air flow. This helps in significantly reducing air leakage from the building, improving energy efficiency, and controlling indoor air quality. As a vapour barrier, it effectively shields buildings from the detrimental effects of water vapour movements in wall assemblies.
Whereas traditional building practices often require the installation of separate air and vapour barriers, new closed-cell spray foams in the market eliminate the need for this. These modern solutions combine high R-value with air sealing and vapour & moisture barrier properties, effectively reducing or even eliminating the need for separate air and vapour barrier membranes, thereby streamlining the construction process. Because of its effectiveness in achieving these results, closed-cell spray foam is popular as an all-in-one solution for both residential and commercial construction projects.

Gaining insight into spray-foam insulation
Spray foam insulation represents a rapidly evolving area in the building materials sector. Some of the latest designs available, such as the new hydrofluoroolefin (HFO)-based Heatlok Soya HP, leverage the newest liquid blowing agent technologies.
New hydrofluoroolefin (HFO)-based blowing agents are among the most environmentally conscious products to date, with a zero Ozone Depletion Potential (ODP) and a Global Warming Potential (GWP) of 1. They have the best R-value of any HFO insulation product currently on the market, with a LTTR value at 50mm of 2.06 RSI (R 11.68). And they are made with recycled plastic materials, rapidly renewable soy oils, and 4th generation blowing agent with zero ozone depleting potential and less than 1 global warming potential. New spray foam solutions adhere to the stipulations of the Paris, Kyoto, and Montreal protocols. As demonstrated by Heatlok Soya HP it’s an insulation material certified as GREENGUARD GOLD.
The Heatlok Soya HP is an industry-leading closed-cell spray foam solution with a low Global Warming Potential (GWP). It is a rigid polyurethane foam system that has been tested and certified by an independent recognized laboratory to meet the stringent requirements for the National Building Code of Canada’s (NBC) CAN/ULC S705. 1-18 ‘Standard for Thermal Insulation – spray applied rigid polyurethane foam, medium density – Material Specification’and CAN/ULC S705. 1-15. These qualifications ensure that the Heatlok Soya HP meets the needs of architects, engineers, builders, and contractors who are committed to constructing high-quality buildings.

Exploring the latest cutting-edge building envelope assembly designs
Architects and specifiers encounter numerous challenges when designing a building envelope. On top of robustness and reliability, they must ensure that it is cost-efficient and compliant with the evolving Continuous Insulation (CI) building codes. Additionally, it is crucial for today’s building envelopes to shield the structure from natural elements and fulfill the growing demands for energy efficiency.
Building envelope assembly design #1
The construction sector is embracing innovative wall systems that incorporate the latest in closed-cell spray foam technology. One standout system comes complete with all necessary components to ensure a strong and airtight building envelope. It provides high-quality products and accessories, supplemented by tailored design support, engineering expertise, and a network of certified installers. This system is a holistic approach designed to enhance the exterior building envelope of any project. It delivers not only high-performance thermal insulation but also features a precisely sealed air barrier system, a vapor barrier, and a Water-Resistant Barrier (WRB), thereby boosting the overall efficiency and durability of the building envelope.
The spray foam application in this assembly is installed completely from the exterior and cuts the thermal bridge of the structure. The advantage of this assembly is the required properties of a high-performance building envelope in a single product (insulation, air, vapor, water). With the ever-increasing requirements for continuous insulation (CI) many buildings now have all the insulation on the exterior. This provides much better performance regarding effective R-value or U-value as the thermal bridges are reduced. The steel studs can then be thinner and empty, leaving room for electrical systems. A wall system like this is usually tested in accordance with CAN/ULC S101 for tall buildings in accordance with article 3.2.3.8. (UL listed – EW24 Assembly) of the National Building Code (NBC) and is approved with many different types of exterior claddings.

Building envelope assembly design #2
This assembly type facilitates the installation of spray foam insulation from the building’s interior, effectively managing thermal bridging caused by studs and structural elements. Consequently, weather conditions and access to facades no longer hinder project progress. The planning, coordination, and implementation of work become simpler and quicker. A significant advantage of this assembly is that enhanced closed-cell spray foam insulation serves as insulation, air barrier, and vapor barrier in a single application, providing all three critical properties of the building envelope. Moreover, the wall assembly supports high-performance thermal resistance and an air barrier system while maintaining very thin wall profiles. For these reasons, construction proceeds rapidly, adheres to deadlines, and is safer, substantially lowering construction costs and hastening the completion of buildings.
The spray foam application used in a wall assembly like this is installed completely from the interior and cuts the thermal bridge of the studs by filling the gap between the exterior sheathing panel (exterior gypsum) and the studs. This gap is variable depending on the insulation values to be achieved and is created with a Z-bar. Z-bars are installed directly on the exterior face of the studs before the sheathing is installed. The spacing and size of the Z-bars vary depending on the type of building and cladding. A reference chart has been validated by an engineering firm. This assembly also complies with CAN / ULC S101 (EW25) and with CAN / ULC S134, for applications in tall buildings.
Both wall assembly examples were rigorously tested and found to comply with the CAN / ULC S742 standard. These assemblies demonstrated excellent performance under high wind loads. Additionally, testing confirmed that both systems met ASTM E331 standards for water infiltration, surpassing the required benchmarks for performance. This highlights their robustness, durability and reliability in critical environmental conditions and confirms the high performance of both Air Barrier Systems.
Conclusion
As extreme weather events become more frequent and intense, the role of air barrier systems in building resilience will only grow in importance, making it a vital area for ongoing research, development, and investment. By understanding the science behind these systems and continuing to advance their technology, the construction industry can better protect buildings and their occupants from the uncertainties of climate change and weather-related damage. State-of-the-art closed-cell spray foams that offer air and vapour barriers in one solution can lead to more streamlined construction processes, improved energy efficiency, and enhanced durability of the building envelope.

About Maxime Duzyk
Maxime Duzyk is the global director of building science and engineering with Huntsman Building Solutions. He holds a background in archi
tecture and has been in the spray foam insulation business for the last 13 years. Maxime is involved with different building envelope committees and associations in North America like CSC, SFC, SPFA, CCMC and ULC Standards.