Photo courtesy of the Canadian Roofing Contractors' Association.
Photo courtesy of the Canadian Roofing Contractors' Association. 
Photo courtesy of the Canadian Roofing Contractors' Association.
Photo courtesy of the Canadian Roofing Contractors' Association. 
The Canadian roofing industry, similar to that of the United States, has made significant progress in the design and construction of roof systems during the past few decades, resulting in the general consensus that most roof systems are performing satisfactorily. Although new roofing products and systems are being introduced more rapidly than ever before, the Canadian roofing industry has managed to avoid many of the grave errors that plagued the industry in the past and resulted in widespread failures and consumer dissatisfaction. Extensive research in the field of building envelope science, dissemination of technical information about roof system performance, and widespread practice of roof system construction monitoring and inspections have led to a better understanding among contractors and designers about the fundamental requirements of satisfactory roof system performance.
Whether by design or happenstance, the Canadian roofing industry is installing better roof systems now than just a few decades ago. Consequently, technical performance, though still critical in terms of the service roof systems provide, no longer is driving the industry. Technical performance as the engine of change has been replaced by larger environmental, social, and health and safety issues. This is not to say technical performance and environmental concerns are mutually exclusive and unrelated. It simply means environmental, health and safety aspects of roofing have been integrated into the definition of the minimum acceptable level of performance.
Canadian consumers increasingly are insisting roofing contractors demonstrate "eco-efficiency." They demand competitively priced roof systems that satisfy the human needs of comfort and reliability and bring quality of life while progressively reducing environmental effects and resource intensity. The profusion of "green" roofing products and practices attests to the predominance of environmental and social concerns in the industry.
For example, Canada recently ratified its Kyoto Treaty commitment to reduce greenhouse gas emissions. Because buildings account for 30 percent of Canada's energy use and 27 percent of Canada's greenhouse gas emissions, ways of incorporating innovative energy efficiency in building design are being sought to meet Canada's greenhouse gas reduction target. In addition, with the recent adoption of the Leadership in Energy and Environmental Design® Green Building Rating System in Canada, the roofing industry also is becoming more aware of sustainable building design and construction and looking into innovative options, such as green roof system technology.
However, because Canada is located in the northern hemisphere where much of the country is subjected to below-freezing temperatures and heavy snowfalls, it has unique constraints in the quest to be "green." Solutions that may be effective in more moderate climates may not be appropriate for Canada.
Rooftop gardens
One would not ordinarily consider Canada to be deficient in green space nor think Canadian cities suffer from the urban heat island effect to the same extent as cities south of the 49th parallel. Canada's urban areas account for only 0.2 percent of the country's total land mass. Furthermore, green space averages 40 percent to 50 percent of total urban use. The Vancouver Parks Board estimates about 44 percent of Vancouver is parks. In 1999, the city of Toronto estimated parks accounted for 21 percent of the region's total land mass.
Even with this relatively high "parks-to-pavement ratio," governments and the public have become concerned about urban sprawl and the effect of urbanization on the environment. Smog and urban heat islands are as much of a concern in Canada's major cities as in the United States. Sustainable construction has become a key priority of urban planning with all levels of government contemplating various incentives to promote environmentally friendly construction.
Rooftop gardens, or green roof systems, have received particular attention. Early in November 2004, Canada's Environment Minister Stephane Dion announced he wished to see trees and flowers on the roof of every federal government building and cited the positive effect green roof systems would have on air quality in cities. He also suggested tax incentives as a means of encouraging their construction.
There are many reasons for the apparent appeal of rooftop gardens to designers and owners, as well as contractors. Canadian roofing contractors are quite familiar with "burying" membranes under insulation and substantial amount of overburden. The protected membrane roof assembly has enjoyed widespread popularity in Canada since the early 1970s. But what is different and increasingly challenging is the form of specifications, contracts and warranties are requiring contractors to be responsible not only for the waterproofing integrity of roofs but also for the performance of the vegetation cover.
The National Research Council Canada (NRC) and industry partners have been studying the energy efficiency and environmental benefits of green roof system technology since 2000 with the establishment of The Rooftop Garden Consortium of which the Canadian Roofing Contractors' Association (CRCA) is a founding member. This public-private partnership includes government departments, national roofing contractor associations and major roofing manufacturers in Canada. The primary objective of the consortium is to collect performance data about green roof systems in a Canadian context. The project started with a proof-of-concept approach—whether and how well the technology would work under Canada's climatic conditions.
Because green roof systems generally do not perform well in the winter and most parts of Canada have cold climates, one task of The Rooftop Garden Consortium is to examine ways to improve their winter performances. This may involve increasing the growing medium depth and planting low-growing ground cover of the evergreen plant species, which are more hardy and durable in northern climates.
If contractors are expected to take on the responsibility for the performance of vegetation cover, as well as the waterproofing elements, standards for both based on the requirements of cold climate environments must be developed. Much of the available information about the construction and maintenance of rooftop gardens has been imported from Europe and may not be applicable to Canada's climate or construction practices. As a result, the consortium is conducting a comprehensive review of existing green roof system standards in Europe and working with ASTM International's Green Roof Task Group to identify information and test methods that will aid in the development of a green roof system standard for Canada.
Modified bitumen
Modified bitumen membranes have been widely used throughout Canada for more than 30 years. A market survey conducted by CRCA in collaboration with NRCA revealed SBS-modified bitumen membrane applications accounted for half the low-slope roofing sales of the survey respondents in 2000 and 2001.
The overwhelming number of installations are torch-applied SBS-modified bitumen membranes, typically consisting of a base sheet and cap sheet. The preferred configuration is a torch-applied base sheet with a torch-applied cap sheet, but mechanically fastened and self-adhering base sheets also are widely used. The popularity of SBS-modified bitumen torch-applied systems is a result of many factors—not the least of which is the flexibility of the applications under various weather conditions. Because below-freezing temperatures are not unusual throughout Canada between October and April, torching provides a larger application window than many other roof membrane materials.
The pervasive use of torches has not been without associated costs. These primarily are related to the relatively high number of incidences of roof fires allegedly caused by torching operations. Such occurrences, combined with other market factors, have caused insurance carriers to scrutinize roofing operations, and, in some cases, carriers have refused to provide contractors insurance.
Lack of affordable insurance has led some firms to abandon hot-applied roofing and others to leave the industry altogether. For those that remain, some relief is being offered by their provincial associations. In the provinces of Quebec and Alberta, CRCA's provincial affiliates—the Quebec Master Roofers Association and Alberta Roofing Contractors Association—provide their members with group-funded insurance whereby group members fund the deductible and an insurance carrier covers losses above the deductible. The Roofing Contractors Association of British Columbia recently announced it established its own insurance company that is wholly owned by its members and licensed by Canada's Financial Institutions Commission. The Ontario Industrial Roofing Contractors Association currently is negotiating with several insurance carriers to develop a program for its members.
In response to the specific concerns about torch safety, CRCA developed a National Torch Safety Program early in 2003 in collaboration with its provincial affiliate associations. Based on current best practices, the program is designed to provide intensive torch safety training to roof technicians. In addition, manufacturers and some roof specification organizations are taking the position that torching directly to wood and other combustible surfaces no longer is acceptable. Some manufacturers are promoting the use of hot-air torches with specially formulated membranes that act as fire blocks and will not support the spread of fire and the use of self-adhering membranes to be used as a fire barrier at curbs, parapets and equipment supports, and details with combustible elements. One manufacturer promotes a self-adhering membrane it claims provides good adhesion at a temperature as low as 14 F (-10 C).
It appears that since the National Torch Safety Program has been in effect, torch-related fires have decreased significantly. However, torch training addresses only one aspect of torch-welding applications. A greater issue is related to the design of structures and the way we build. In Canada, a large number of smaller buildings—in the commercial and residential sector—are of wood frame construction. These pose particular risks because of the nature of the materials used and many "hidden" roof and wall spaces encountered.
The largest single construction loss in Canadian history occurred in 1999 in Downsview, a satellite community of Toronto, when an entire condominium complex of wood frame construction was reduced to ashes after being accidentally ignited by a roofing worker's torch. This and similar events have caused Canadian roofing contractors, roof system designers and even roofing product manufacturers to rethink the use of torches on this type of construction.
Adding to the problem is that fire-protection requirements in Canada's building codes primarily address occupied and completed buildings, and fire protection during construction is largely ignored. Firewalls, fire separators and other fire-protection requirements routinely are not in place when roofing operations are under way, facilitating the spread of fire and exacerbating the problems of containing a fire once started. CRCA intends to advocate changes in Canadian building codes during the next round of revisions that will address current shortcomings with respect to fire protection during construction.
The risks associated with torch welding have led to renewed interest in cold-applied modified bitumen applications. In 2004, CRCA published Technical Bulletin Volume 54, "Cold Adhesive Applied Modified Bitumen Membranes," advising contractors of general precautions and application procedures concerning their use. Although the number of cold-applied membranes has increased significantly, they still are restricted to warm-weather installations with most manufacturers specifying a temperature window of 41 F to 104 F (5 C to 40 C). Some manufacturers have developed adhesives ostensibly designed for applications near or below freezing, but their use has been limited to date.
It is interesting to note that at the same time adhesive-applied installations are growing in popularity and manufacturers are formulating lowerapplication temperature adhesives, usually with a higher solvent-to-solids ratio, the Canadian federal government has announced an initiative to reduce emissions of volatile organic compounds (VOCs) from consumer and commercial products. Regulations under the Canadian Environmental Protection Act are being developed to establish Canadian national standards for three product categories: consumer products; architectural coatings, which include roof coatings and adhesives; and automobile refinish coatings. The Canadian federal government has stated it intends to align Canadian VOC product standards with those of the United States. This may include VOC content limits used in U.S. Environmental Protection Agency regulations, as well as those adopted by the U.S. Ozone Transport Commission and California.
The effect these initiatives will have on cold-process roofing applications has yet to be seen, but it appears the dual requirements of an effective cold-temperature adhesive with a low VOC content are inconsistent with current technology. Indications are that torch welding will continue to be the preferred method of modified bitumen membrane application in the foreseeable future. The safe application using this method will continue to be of concern to contractors and their insurers.
Insulation
The building envelopes of structures in northern climates require the inclusion of materials with low thermal conductivity to make them habitable and fit for human comfort. Canada's relatively sparse population, vast geography and cold climate combine to make Canadians heavy users of energy by world standards. Per capita energy consumption is about 70 percent above the Organisation for Economic Co-operation and Development (OECD) average. Canada ranks 27 out of 29 OECD nations in terms of energy use per capita. Only residents of Iceland and Luxembourg use more energy per capita than Canadians. In such a situation, the pressure for environmental restraint is mounting.
The response of the Canadian roofing industry has been twofold. First, efforts have been made to achieve thermal efficiency in design through the correct calculation of the long-term thermal resistance (LTTR) of insulation materials. This has been particularly challenging with cellular plastic insulations that rely on captive blowing agents other than air for their long-term thermal resistance. It has been well-established the conductivity of these insulations, which include polyisocyanurate, extruded polystyrene and spray polyurethane foam, increase over time.
In 2000, Underwriters Laboratories of Canada (ULC) issued the first edition of CAN/ULC S770, "Standard Test Method for Determination of Long-Term Thermal Resistance of Closed-Cell Thermal Insulation Foams." This prescriptive approach to determining long-term thermal resistance of closed-cell thermal insulating foam based on the ASTM C1303, "Standard Test Method for Estimating the Long-Term Change in the Thermal Resistance of Unfaced Rigid Closed Cell Plastic Foams by Slicing and Scaling Under Controlled Laboratory Conditions," thin slicing technique now is an integral requirement of the Canadian Standards for closed-cell foam insulation.
ASTM C1289-02, "Standard Specification for Faced Rigid Cellular Polyisocyanurate Thermal Insulation Board," also requires LTTR for polyisocyanurate insulation be tested and reported.
When the first edition of CAN/ULC S770 was issued, it was understood by the ULC Committee for Thermal Insulation that as more data were generated using this procedure, revisions to the standard would be needed. The second edition, CAN/ULC S770-03, published in 2004, represents the first step in refining the standard and addresses some of its initial shortcomings. These revisions include the following:
These and other changes represent a significant improvement to the first version of CAN/ULC S770. The task group has been reconvened by the ULC Committee for Thermal Insulation with the task of addressing the issue of bias in the next set of revisions to further refine the method. It will be interesting to see whether industry organizations will adopt this edition.
In addition to determining the actual thermal resistance of insulation, the Canadian roofing industry and other construction industries and Canadian research government organizations are exploring the potential application of new thermal materials in the building envelope. One such candidate is vacuum insulation panels (VIPs).
Figure courtesy of National Research Council Canada's Institute for Research in Construction.
Comparison of thermal resistivity of various insulating materials.
According to NRC's Institute for Research in Construction, the thermal insulating capacity of VIPs is several times higher than conventional insulating materials (see figure). The higher insulating values of VIPs effectively can reduce the thicknesses of building envelopes. In cases where the size of framing members is governed by their abilities to contain insulation materials rather than structural strength, the size of insulation cavities can be reduced with a saving in materials. In addition, it will result in a maximization of usable building space and reduction in waste and recycling needs.
VIPs have been widely used in the refrigeration and pharmaceutical industries since the 1990s. Initially, they were produced as flat, rigid panels, but recently, they have been produced in different shapes and in flexible form. These options open up opportunity to use VIPs in building envelope applications. There exists a huge potential for VIPs to be used in every part of building envelopes, including roof systems, as insulating materials. However, there are many technical issues that need to be resolved, including the need to provide a robust material capable of withstanding rough handling and in-service exposure.
NRC's Institute of Research in Construction has initiated a "High-performance Insulation Materials" (HPIM) research study focusing on the performance and longevity of VIPs and the development of design considerations for the application of VIPs in the field. The HPIM consortium expects the efforts of this research will lead to the development of VIPs suitable for use in roof systems and other building envelope elements.
Fall protection
Ecological and public safety issues are not the only challenges facing the Canadian roofing industry.
Worker safety remains a key element in shaping the work environment as health and safety regulations become increasingly stringent. The issue of fall protection continues to dominate the industry. Although strict fall-protection regulations have been adopted in every Canadian province and require training, injuries and fatalities from falls continue to plague the Canadian roofing industry.
It is the position of CRCA and its provincial affiliate associations that the emphasis should be on fall avoidance as opposed to fall arrest. Ideally, a roofing worker should be prevented from coming too close to the edge of a roof or sliding down a sloped roof.
In 1999, CRCA approached the Canadian Commission on Building and Fire Codes and requested the National Building Code be revised to include a requirement that all newly constructed buildings be designed with permanent inserts or slots at low-slope roof perimeters so temporary guardrails can be installed for construction purposes and subsequent roof system maintenance work. This request recognized safety lines are effective for most steep-slope roof applications but are impractical on a majority of low-slope roof installations. The initiative also was intended to address current regulations that place responsibility for fall protection entirely on the contractor and workers, ignoring the contribution of a roof system's design to worker protection. For example, though regulations require "tying off" near roof edges, often there is nothing to which workers can tie off.
Although the initial attempt to have the requirement for permanent guardrail inserts included in the National Building Code was unsuccessful, efforts by the Ontario Provincial Labour Management Health and Safety Committee and Construction Safety Association of Ontario are under way to have similar requirements included in the next edition of the Ontario Building Code. Concurrent with Ontario's initiative, CRCA once again will request an amendment in the next edition of the National Building Code to include similar requirements. The purpose of such a request is to ensure fall-protection requirements are recognized in a building's initial design and construction.
A new horizon
In the not too distant past, the major concern of Canadian roofing contractors was to overcome the difficulties associated with installing roof systems in cold or wet winter conditions that would provide consumers with reliable, long-term service. This led to the development of roof systems and application techniques best-suited to the conditions encountered in the various regions of the country.
Currently, however, waterproofing integrity and reliability are not the only factors determining how roof systems are installed. Roofing contractors must be aware of the environmental, health and safety effects of their activities. In some instances, these take precedence over strictly technical performance, limiting contractors' choice of materials and applications.
The Canadian roofing contractor associations in collaboration with research organizations, such as NRC's Institute for Research in Construction; manufacturers; and other industry organizations are undertaking projects designed to meet these demands. Roofing professionals hope the regulatory and design communities will recognize the challenges facing contractors and work cooperatively with the roofing industry to overcome them.
Peter Kalinger is CRCA's technical director.
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