Elevating building efficiency with roofing and insulation

by arslan_ahmed | January 19, 2024 1:53 pm

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By Maxime Duzyk

In an era increasingly focused on energy conservation and carbon footprints, the architectural and engineering design of buildings must shift toward a more sustainable and resilient future. This change greatly involves the careful selection of materials used for insulation and in concert with roofing systems. A building’s thermal envelope, primarily determined by insulation and roofing, plays a critical role in managing energy consumption, ensuring environmental resilience, and creating a comfortable indoor environment.

Spray foam insulation has emerged as a leading solution in this transition due to its energy efficiency, durability, and performance when compared to traditional insulation materials. Specifically, hydrofluoroolefins (HFO)-blown spray foam insulation in conjunction with soundproofing applications offers significant benefits.

It is essential for architects, engineers, builders, and contractors to recognize the interconnected nature of different building components. HFO-blown spray foam, when used in building walls, can complement a high-quality roofing system. Its insulative properties create a seamless barrier that prevents air leakage and resists water penetration, thereby fortifying the building and enhancing thermal efficiency. Proper installation by experienced experts eliminates the need for additional vapour barriers, simplifying construction processes and reducing costs.

Importantly, HFO-blown spray foam emerges as an environmentally conscious choice. With a low global warming potential (GWP) compared to conventional hydrofluorocarbon (HFC)-blown spray foam and other insulation materials, it performs better in sustainable development projects.

This article explores the unique benefits of using HFO-blown spray foam in combination with roofing structures, focusing on its contribution to energy efficiency, durability, water resistance, flexibility, ease of installation, and positive environmental impact.

Exploring the qualities

Spray foam insulation can be seamlessly integrated with various roofing systems, including flat, round, or sloped roofs. Its compatibility allows it to adhere well to different substrates and contours, ensuring a consistent and effective insulation layer without compromising the roofing system’s design or functionality.

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The integration of spray foam insulation with various roofing systems enhances a building’s overall performance and sustainability. Here is how this combination works seamlessly to provide numerous benefits:

• Energy efficiency. A well-insulated building envelope is key to energy efficiency. When there is spray foam insulation in the walls, it minimizes heat loss or gain through the building’s exterior. In summer, the air conditioning system does not have to work as hard, and in winter, the heating system can maintain a comfortable temperature without excessive energy consumption.
• Moisture control. A reliable roofing system ensures that water does not penetrate the roof and infiltrate the building. However, moisture can also enter a structure through walls. Spray foam insulation creates a moisture-resistant barrier, preventing water vapour from entering the walls and causing problems such as mould and rot.
• Condensation prevention. Roofing systems are susceptible to condensation issues, particularly in areas with fluctuating temperatures. Spray foam insulation helps mitigate this risk by providing an insulation layer that reduces the potential for condensation to form on the underside of the roof deck. This is crucial for preventing damage to the roofing materials.
• Air sealing. Air leaks in a building can significantly compromise energy efficiency. Spray foam insulation provides an airtight seal, reducing drafts, and heat loss. This complements a good roofing system by ensuring conditioned air stays inside and exterior unconditioned air outside, resulting in consistent indoor comfort.
• Structural strength. Some roofing systems, such as green or living roofs, can add extra weight to a building. Spray foam insulation is lightweight and has demonstrated to increase structural strength, which helps in maintaining structural integrity. It does not add much load to the walls, making it a suitable choice in combination with various roofing designs.
• Seamless integration. Spray foam insulation is applied as a liquid and expands to fill gaps and cavities. This allows for a seamless integration between the insulation and the building’s structure, including the areas where the walls meet the roof. This seamless application ensures there are no weak points in the building envelope.
• Long-term savings. When spray foam insulation and a quality roofing system are used together, they create a synergy that enhances the building’s overall performance. This can lead to long-term savings in energy costs for building owners, reduced maintenance costs, and improved durability that leads to an extended roof lifespan.
• Thermal efficiency. Spray foam insulation, when applied to the underside of the roof deck, creates a continuous and airtight barrier. This barrier significantly reduces heat transfer, helping maintain a stable and comfortable indoor temperature. In colder climates, it prevents heat loss during the winter, while in warmer climates, it keeps the building cooler by preventing heat gain. This collaboration between the roofing system and spray foam insulation contributes to substantial energy savings over time.

Spray foam insulation is a valuable addition to a good building roofing system, enhancing thermal efficiency, moisture control, air sealing, structural integrity, condensation prevention, compatibility, and long-term savings. It is essential to understand how the combination of the two improve the overall performance and sustainability of their buildings.

Roofing systems that benefit from spray foam insulation

The decision to use spray foam insulation in a building’s walls in conjunction with specific roofing systems depends on various factors and environments, including climate, building type, and energy efficiency goals. However, some roofing systems are particularly well-suited to benefit from the addition of spray foam insulation in the walls.

For example, buildings with flat or low-slope roofs often require more attention to insulation because they are more susceptible to water infiltration and have less natural drainage. Spray foam insulation in the walls and roof in conjunction with coatings can provide additional moisture control and thermal performance, especially when paired with roofing systems such as built-up roofing (BUR) or single-ply membranes.

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Green roofs are designed to support vegetation, which can add weight to the roof. Spray foam insulation is lightweight and can help support the additional load while providing effective insulation. It also contributes to energy efficiency, as maintaining a consistent temperature within the building is crucial when vegetation is present on the roof.

Then there are metal roofs in copper, aluminum, and various forms of steel, and they can be susceptible to temperature-related issues such as condensation. Spray foam insulation in the walls and roofs helps prevent condensation by providing an airtight barrier that reduces the potential for moisture buildup on the underside of the roof deck.

In Canada, the roofing systems exposed to extreme climates experience temperature fluctuations, such as very hot summers and cold winters. The use of spray foam insulation in walls and roofs can be especially beneficial. It helps maintain indoor comfort and reduces energy costs by complementing roofing systems that are designed for such climates.

The National Energy Code of Canada for Buildings (NECB) applies to large buildings and sets out the technical requirements for the energy-efficient design and construction of new buildings and additions. In the mandates of reducing greenhouse gas (GHG) emissions in buildings, builders are considering energy-efficiency focused roofing systems. These systems are designed with a strong focus on sustainability, such as cool, reflective, green roofs, and can benefit from the thermal performance of spray foam insulation in the walls.

Finally, there are roofing systems with complex designs. Buildings with intricate roof layouts, multiple levels, or unusual shapes may have more challenges when it comes to insulating the roof itself. In such cases, spray foam insulation in the walls and roofs can ensure there are no gaps or areas where heat transfer or air leakage can occur.

Addressing the requirements of a complex roof design

Insulation professionals will work closely with architects and builders to develop customized insulation solutions that address the specific challenges posed by complex roof designs. This may involve combining spray foam insulation with other insulation materials or techniques to achieve optimal results.

Exterior spray foam application technique

For example, consider a spray foam application technique where the foam is installed completely from the exterior and cuts the thermal bridge of the structure. The advantageous aspect of an assembly system of this kind is that architects and engineers will get all the required properties of a high-performance building envelope in a single product (insulation and an air, vapour, and water-resistive barrier in rain screen applications). This is a great accompaniment to a complex roof design as the spray foam can go right up to the parapet line and provides a 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.

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When considering such a system, it is ideal to do some investigation and ensure it has been 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 different types of exterior claddings. With the ever-increasing requirements for continuous insulation (ci), many commercial buildings and multi-unit dwellings (MDUs) now have all the insulation on the exterior.

Interior spray foam application technique

A complex roofing system can also leverage the benefits of an interior spray foam application technique that can be installed right below the roof deck. This is where an HFO spray foam 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 can vary 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 applied. The spacing and size of the Z-bars will vary depending on the type of commercial building or MDU and cladding. Again here, architects and engineers should research interior assembly systems that have successfully completed the CAN/ULC S101 test in accordance with article 3.2.3.8. of the Canadian building codes and are UL certified with the UL EW25 assembly. Some of these spray foam application systems are also Greenguard gold certified, which means they are low volatile organic compounds (VOCs) emission to ensure better indoor air quality (IAQ).

In addition to innovative application techniques, there are new HFO blowing agents on the market today. Spray foam installers can get access to HFO solutions with exceptional R-value, with a long-term thermal resistance (LTTR) value at 50 mm (1.9 in.) of 2.06 RSI (R-11.68), a zero-ozone depletion potential (ODP), and a GWP of one, which is more than two orders of magnitude (99.9 per cent) lower than HFCs used in this industry. SPF can be used in all roofs, by exterior with a vented cavity or by interior unvented. For complex roofs, this reduces the risk of condensation as inadequate ventilation can lead to issues. Complex roofs are often very hard to ventilate. Quickness of installation compared to other systems, ensures the air and vapour barrier properties are perfect and all installed by the same installer.

Today’s modern architecture frequently showcases buildings with complex roof designs—be it curves, slopes, or even undulating forms. Such complexity is not merely esthetic but often serves functional and environmental purposes such as natural lighting, water drainage, or thermal efficiency. However, these unconventional shapes present challenges in terms of insulation. Traditional insulation materials such as fibreglass or cellulose can be cumbersome to install in non-linear forms, leaving gaps and creating thermal bridges that compromise efficiency.

The continuous nature of spray foam allows for seamless application, adhering to irregular surfaces, crevices, and hard-to-reach corners. This ensures a seamless insulation layer, effectively eliminating thermal bridges and gaps. Closed-cell spray foam not only insulates but also adds structural strength. This is particularly beneficial in large, complex building projects, where the roof design may involve spans or cantilevers in its design which would benefit from additional reinforcement.

To demonstrate the efficacy of spray foam insulation in complex large building roof designs, one can consider some examples. Sports stadiums have intricate roofs that may be retractable or feature unconventional geometries for esthetic or functional reasons. Spray foam insulation can be successfully used to not only maintain thermal comfort but also to add structural support. There are industrial warehouses, that unlike typical flat or gabled roofs, some of the modern ones incorporate curved or saw-toothed roofs for better natural light and ventilation. Spray foam insulation is a proven effective solution for such designs, delivering thermal efficiency without compromising the architectural vision.

With the housing shortage in Canada and increased urbanization, there is a demand for the development of more MDUs/residential buildings. In 2021, nearly three in four Canadians (73.7 per cent) lived in
one of Canada’s large urban centres, up from 73.2 per cent five years earlier.¹

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This means builders, architects, and engineers need to ensure new condominiums and apartments meet standards around affordability, energy-efficiency, and ultimately reduce environmental impacts. They also need to be comfortable, in terms of heating and cooling. Spray foam insulation in an internal or external assembly technique is efficient in the construction stages, and it enhances the overall resilience of building roofs, creating structurally sound, comfortable, energy-efficient living spaces.

In Toronto, there were 38,780 multi-unit starts in 2022—the largest number on record—with the majority being apartments and condominiums; while rental projects in Montreal represented 61 per cent of all housing starts.²

Recent MDU building projects worth mentioning: Le Viridi condos, a luxurious Quebec condo rental development in the Pointe-aux-Lièvres eco-district,³ and Mon Symposium Phase 2 in Lebourgneuf. The first phase comprises of 737 MDUs and phase 2 includes 166 units.⁴ The insulation for both these buildings was carefully considered and selected to deliver greater energy efficiency, comfort, and acoustical performance.

During the construction phase, both benefitted from an interior insulation method/technique where the three main properties of the building envelope were provided by one HFO spray foam insulation product that acts as an insulation, air barrier, and vapour barrier in a single application. With the quickness of installation, easier sequencing as the insulation and exterior finish can be installed at the same time—leading to cost savings for heating (winter projects) and major time savings.

Prior to the interior spray foam insulation application, it is essential to ensure substrate materials are within recommended moisture content ranges, especially in wood structures and this is critical for several reasons. These factors play a vital role in both the short-term effectiveness and long-term durability of the insulation, as well as the overall structural integrity of the building. For example, for spray foam insulation to adhere properly and perform effectively, the substrate, in this case, wood must be within a certain moisture content range which is 19 per cent for wood, in accordance with the building code. If the wood is too damp, the spray foam may not adhere properly, leading to gaps or delamination. This can compromise the insulation’s effectiveness in terms of thermal resistance (R-value) and air sealing.

Conclusion

Spray foam insulation stands as a versatile, effective, and structurally reinforcing material that caters well to the intricacies of complex large building roof designs. From seamless application and high thermal resistance to added structural integrity and moisture control, spray foam brings a multitude of benefits to the table. As the industry continues to push the boundaries of architectural design and engineering, embracing innovative materials such as spray foam insulation will undoubtedly be pivotal in realizing more sustainable, efficient, and structurally sound buildings for the future of Canada.

Notes

¹ Refer to the Statistics Canada report by visiting www.150.statcan.gc.ca/n1/daily-quotidien/220209/dq220209b-eng.htm[6].

² Visit the Canada Mortgage and Housing Corporation (CMHC) at www.cmhc-schl.gc.ca[7].

³ See project Le Viridi, condosleviridi.ca[8].

⁴ Learn more about Phase 2 of Mon Symposium, blancetnoircondosneufs.ca/projets/mon-symposium-phase-2[9].

 [10]Author

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

Source URL: https://www.constructioncanada.net/elevating-building-efficiency-with-roofing-and-insulation/

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