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