b'Roof Assembly LimitationsA roof assembly can consist of many different components, includ-ing but not limited to the vapour barrier, insulation, cover and overlay boards, membrane and surfacing/ultraviolet (UV) protection. To achieve good results, all these components must be properly installed.Assemblies can be put together using various methods and techniques. For example, vapour barriers can be installed loose-laid or by using hot asphalt, cold-applied adhesives or self-adhering membranes. Similarly, the insulation can be installed using mechanical fasteners or glues or mopped in place with hot asphalt. Mechanical fastening is not inherently tempera-ture sensitive, but the sealing of membrane terminations and laps may be difficult to complete. There are also situations in which electrical conduits are secured to the underside of the steel deck, where mechanical fastening may pose a risk of puncturing conduits.Finally, the membranes can be glued over the cover boards/insulation, mopped with hot asphalt, mechanically fastened or (assuming the appro-priate noncombustible substrates exist) torched in place.The designer/contractor and owner need to understand the limitations of various assembliesespecially the materials comprising themin the weather conditions anticipated during installation. For instance, chemical A doghouse used to keep adhesives within the required temperature range. adhesives for insulation layers and some self-adhering membranes have strict limitations on installation temperature. The use of hot asphalt is generally considered one of the most versatile options available when it comes to the installation of a roofing assembly in cold conditions. How-ever, like all systems, this has limitations. For one, hot asphalt roofing systems require available, clear ground area for kettle setup, as the kettle generally cannot be placed on the roof. Their use is further limited to the height the liquid asphalt can be pumped or shuttled to the roof. This can pose a challenge when working in a built-up environment (e.g. city core) or on very tall buildings.Compounding these limitations is the asphalts rate of cooling as it is transferred from the kettle to the roof. Low temperatures cool asphalt rap-idly and crews have to work very quickly to apply it before it drops below its required application temperatures. The contractor may try to overheat the asphalt at the kettle to combat this, but if the asphalts temperature is With this project, use of conventional drying techniques was prohibited, so the contractor had to tarp the roof to minimize the effort involved in drying it. raised beyond the recommended level, the quality of the asphalt will be compromised (reducing the service life of the roof) and the risk of kettle fires will increase. Moreover, asphalt has a strong odour, which may be objected to by the building users.Cold-applied adhesives have the benefits of requiring limited storage space, offering easy handling and being relatively odour-free. However, some cold adhesives take longer to install and cure compared to hot sys-tems. Also, cold systems have strict manufacturer limitations on allowable temperature range before performance and manufacturers warranties are threatened. Many adhesives have storage and application temperatures above 4 to 5 C (39 to 41 F). Although installation temperature require-ments vary from one manufacturer to another, there are few adhesives that can be used for below-freezing conditions, which may require special equipment to facilitate installation. The manufacturer should always be consulted for installation requirements, particularly when using products in cold-weather applications.Someprojectsrequiremoreenvironmentallyfriendlyoptionslow involatileorganiccompounds(VOCs).However,beingwater-based/ moisture-cured, these adhesives typically have more stringent tempera-ture limitations (above 5 C) for application and cure periods.As with adhesives, self-adhering membranes have temperature limits A contractor working at critical details during winter conditions. with respect to storage and installation. While some are restricted to a minimum installation temperature of 5 to 10 C (41 to 50 F), winter-grade self-adhering membranes may be installed at temperatures as low as -5 C (23 F). In theory, this sounds great, but what happens when the daily high is -7 C (19 F)? Should the team push to install the cold-weather mem-brane anyway? If the membrane is installed at -7 C (19 F), what about when the temperatures drop to -9 C (16 F)?Manufacturers have strict protocols pertaining to the storage and in-stallation temperatures (substrate, product and ambient air temperatures, during and after) for their respective products and may require adhesives and membranes to be stored indoors or within heated/insulated contain-ers (typically located onsite).Pushing beyond temperature installation limits will happen, particu-larly when one considers schedule (work must be completed by a given time), onset of weather (the push to install before the cold and snow really sets in), and the tried-and-true approach (when the team has pushed to A snow-covered roof poses significant challenges, especially with rooftop mechanical equipment. those temperature levels before).ORN THE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIO ONTARIO ROOFING NEWSISSUE 3 20199'