The Rise and Development of Single-Ply Roofing Systems in China
1. History of Single-Ply Roofing Systems Abroad
In Europe and the United States, commercial roofing systems are generally divided into build-up roofing and single-ply roofing systems. Build-up roofing utilizes a multi-layer waterproofing system (BUR), typically using materials such as felt or modified asphalt. Single-ply roofing emerged in the 1960s. The first generation of single-ply roofing materials used synthetic rubber as an exposed waterproofing system, including chloroprene rubber (CR) and butyl rubber (IIR). For example, the Washington Dulles Airport terminal, completed in 1961, employed chloroprene rubber coated with chlorosulfonated polyethylene (CSM). Later, single-ply roofing increasingly utilized single-layer flexible synthetic polymer waterproofing membranes, such as PVC, TPO, and EPDM. These products offer consistent quality and can be fastened using a variety of methods, including full-bonding, mechanical fastening, and pressure-bonding. Single-ply roofing systems are already a mature technology in Europe and the United States.
In Europe and the United States, the single-ply roofing market is highly mature, encompassing a robust market for waterproofing membranes, insulation materials, fasteners, adhesives, and other system components. There is a well-established market, with a highly trained and certified team of contractors and professional construction practices. Standards and relevant testing agencies are in place, ensuring effective oversight. Furthermore, the single-ply roofing industry is highly specialized, with relevant associations such as the European Single-Ply Waterproofing Association (ESWA), the Single-Ply Roofing Association (SPRA), and the Single-Ply Roofing Industry (SPRI) serving as industry platforms. These associations focus on technical exchange, industry training, and certification, and actively participate in the development of standards, test methods, and local legislation and regulations, helping member companies operate efficiently and secure a larger market share.
Single-ply roofing membranes in Europe and the United States come in two main categories: thermoplastic and thermoset. Thermoplastic membranes are polymer materials primarily composed of plastic polymers. Their joints are welded using hot air or chemical welding, ensuring joint strength no less than that of the parent material. Thermoset roofing membranes have high requirements for joint preparation, requiring the use of special adhesives or tapes. Cleaning and repairing the membranes are also expensive. Most single-ply roofing membranes contain reinforcements, providing high strength and dimensional stability. Common reinforcements include polyester mesh and fiberglass.
Thermoplastic PVC roofing membranes have been in use for over 50 years, having been in use since the early 1960s. Their production and application technologies are mature, resulting in a service life of 20 years or more, and their durability has been proven in real-world projects.
Thermoplastic elastomer polyolefin (TPO) roofing membranes, commonly known as FPO in the European market and TPO in the US, are experiencing rapid growth in their use in single-ply roofing systems.
Thermoset rubber materials primarily refer to EPDM roofing membranes, which offer strong weather and chemical resistance and a long service life.
Over the past 30 years, TPO roofing membranes have gradually become one of the leading materials of choice for single-ply roofing internationally. In 2003, ASTM D 8678, "Standard Specification for Thermoplastic Polyolefin Roofing Membranes," was released. Its heat aging performance test specifies a test temperature of 116°C for 28 days, and a weathering test using a xenon arc tester.
In December 2009, ASTM's TPO Research Group investigated whether early failure of TPO roofing systems is associated with high-temperature exposure. The group concluded that UV aging does not appear to be a problem for TPO membranes; instead, high temperatures may increase the risk of failure. Therefore, ASTM decided to tighten the standard requirement, extending the 116°C test duration from 28 days to 224 days. This standard was published on June 1, 2011.
TPO membranes must exhibit higher heat resistance and incorporate either a thicker top layer or a weathering layer to meet the stringent requirements of the ASTM standard. Therefore, there is room for research in TPO surface coatings and the addition of surface anti-aging agents.
1.2 Single-ply Roofing Systems in the United States
Around the 1990s, single-ply roofing membranes in the United States were primarily thermoset and thermoplastic. Thermoset membranes were primarily ethylene propylene diene monomer (EPDM) rubber-based materials. Among thermoplastic materials, in addition to traditional PVC membranes, the use of elastic polyolefins (TPOs) has rapidly grown over the past 30 years, dominating the US single-ply roofing market. TPO membranes have been used on over 1 billion square meters of floor space in the US and are a durable, sustainable, and high-performance roofing material.
Due to their rapid and convenient installation, TPO membranes have been widely used in repair roofs in the US in recent years.
1.3 Single-ply Roofing Systems in Europe
In Europe, the primary materials used for single-ply roofing systems are thermoplastic membranes, including PVC membranes, which began development in the late 1950s, ethylene-vinyl acetate-bitumen blends (ECB), ethylene-vinyl acetate copolymers (EVA), chlorinated polyethylene (CPE), and elastomeric polyolefin (FPO) membranes developed in the 1990s. Membrane thickness is at least 1.2 mm, with a trend toward increasing thickness. PVC membranes dominate the European single-ply roofing market, with modified asphalt membranes also occupying a small market share.
2 The development of single-ply roofing systems in China began in the 1990s
2.1 European single-ply roofing PVC membrane systems entered China in 1994
As early as 1994, Sika of Switzerland installed the first single-ply roofing project in Beijing using internally reinforced PVC waterproofing membrane: the AMECO hangar at Beijing Capital Airport (Figure 1). Although Sika had not yet established a polymer waterproofing membrane production line in China at that time, the AMECO hangar was the first application project of the single-layer roofing system in mainland China.
Figure 1 Beijing Capital AMECO hangar roof (single-layer PVC membrane)
2.2 European Single-Ply Roofing Membrane Manufacturers Established Factories in China in 1998
In 1998, Sarnafil, a Swiss waterproofing systems manufacturer, entered the Chinese market. They established Sarnafil Luquan, a joint venture with Jinan Plastics Factory No. 1, to produce PVC waterproofing membranes. This marked the first time foreign investment entered the Chinese polymer waterproofing membrane market (Figure 2). In 2001, the Swiss company acquired the remaining equity of its Chinese joint venture partner and renamed itself Sarnafil Waterproofing, becoming a wholly Swiss-owned company in China. In 2005, Sarnafil invested in a fully imported PVC membrane production line in Xinzhuang, Shanghai, specializing in the development, production, and sales of PVC waterproofing membranes. This marked the beginning of the development of polymer (PVC) waterproofing membranes and single-ply roofing systems in China.
Figure 2 China’s first single-layer roof PVC waterproofing membrane production line was put into operation
2.3 The Entry of Multinational Companies Promoted the Development of Single-Ply Roofing Systems in my country
Following Sarnafil of Switzerland, international roofing giants such as Carlisle and Firestone entered the Chinese market. The entry of multinational companies not only brought new products and technologies, driving the development of single-ply roofing systems in my country, but also cultivated a large number of professionals specializing in polymer waterproofing membranes. Simultaneously, the concept of "waterproofing systems" began to spread and permeate China, encompassing products and accessories related to the entire roofing system, including insulation, fasteners, adhesives, and more. Furthermore, the entry of multinational companies provided a bridge and link for technical exchange and communication between the Chinese and international waterproofing industries. Since then, China has made significant progress in waterproofing material standards, technical regulations, testing methods, system component requirements, application technology, and construction skills training, rapidly aligning with those in Europe and the United States.
3.Early Barriers to the Promotion of Single-Ply Roofing Systems in my country
Single-ply roofing systems began to develop in China in the 1990s, but encountered numerous obstacles to their promotion. First, China previously widely used multi-layer asphalt waterproofing membrane (BUR) systems, which achieved the required waterproofing of a building by stacking multiple layers. International single-ply roofing systems, on the other hand, used a single layer of polymer waterproofing membrane, achieving the same waterproofing effects as traditional multi-layer membranes. This marked a significant gap in design concepts.
Furthermore, China lacked product standards and drawings, technical specifications and procedures, application techniques, and construction method guidelines for single-ply roofing at the time. There was a shortage of skilled and experienced construction teams, and supporting materials, fasteners and gaskets, construction equipment, and prefabricated components were all undeveloped. Furthermore, there were no testing methods or institutions for roofing system safety.
Thus, although single-ply roofing system products appeared in China in the 1990s, they faced significant challenges in market adoption. 9. Development of Fasteners, Construction Equipment, and Prefabricated Components for Single-Ply Roof Systems
4.Development of single-layer roof system fasteners, construction equipment and prefabricated parts
4.1. Development of Fasteners for Mechanical Fixing Systems for Single-Ply Roofs
Mechanical fixing is the most important method for securing waterproofing membranes in single-ply roof systems, accounting for over 70% of all single-ply roof systems. Fasteners, as key components in mechanical fixing systems, play a crucial role. With the entry of international brands such as Sika Sarnafil around the beginning of the 21st century, single-ply roof systems gained popularity in the Chinese market, creating a demand for specialized fasteners for mechanical fixing. Imported brands such as SFS of Switzerland and ITW of the United States also introduced corresponding technical requirements, design standards, and testing methods, providing solid support for the promotion and application of single-ply roof systems (Figure 3).
Figure 3 SFS fasteners used in Guangzhou Honda Automobile Project
In the mid-to-late 2000s, driven by the China Building Waterproof Association, the Chinese and international single-ply roofing industries engaged in extensive technical exchanges. Related companies also conducted research on the introduction, absorption, and localization of single-ply roofing component technologies, leading to rapid development of domestic fasteners. In the early 2010s, domestic fastener companies, represented by Daohai (the predecessor of Huitao), emerged. Drawing on mature European and American technologies and integrating domestic realities and accumulated practical experience, they developed, produced, and promoted the use of fastener products, thus promoting the localization of single-ply roofing system fasteners.
Today, the variety of domestic fastener systems is relatively complete, ranging from metal point fixing systems, anti-cold bridge fixing systems, linear fixing systems, to non-perforated matrix fixing systems. Although product quality varies widely on the market, high-end domestic fasteners are now comparable to well-known European and American brands and are used in many large-scale, high-end projects, such as the Shenyang BMW project and the Beijing Daxing International Airport project (Figure 20). The fastener system has experienced the same process as single-layer roofing waterproofing membrane, from relying on imported brands in the past to the booming development of local brands today.
Figure 4 Domestic fasteners used in the Shenyang BMW and Beijing Daxing International Airport projects
Unlike general-purpose fasteners, fasteners for single-ply roofing systems possess three distinct characteristics: precise application, challenging quality control, and complex management and traceability. This requires fastener manufacturers to possess deep expertise in application technology, enabling them to select products based on specific application scenarios and provide integrated services. They must also establish quality control systems to address the challenges of complex processes and supply chains, as well as product stability. Furthermore, they must implement rigorous and standardized ERP systems to manage and trace the diverse and small-batch inventory of single-ply roofing fasteners.
In 2017, Huitao's fastener product line achieved the first-ever US FM certification, enabling third-party traceability control for domestic brands, from product testing to system certification. This marked a new milestone in the development of my country's single-ply roofing fastener industry.
4.2 Hot Air Welding Equipment
Before the introduction of single-ply roofing systems in China, the primary method for joining polymer materials was adhesive bonding, which presented low reliability, as well as issues with compatibility between adhesive and membrane material and joint durability. With the entry of single-ply roofing systems into the Chinese market, the connection of thermoplastic membrane seams has also begun to evolve to hot air welding. As early as 1952, the Swiss Leister Group designed and manufactured the world's first hot air welding gun for plastic welding. It subsequently developed specialized tools for welding PVC roofing materials. In 2004, the Leister Group established Leister Plastic Welding Technology (Shanghai) Co., Ltd. in Shanghai, providing localized technical support and after-sales service to meet the specific needs of Chinese customers.
The Leister Group offers a variety of roof welding tools, including heavy-duty welders with wrinkle-resistant designs; medium-duty welders suitable for welding light steel roofs; light-duty welders suitable for welding glass wool on metal roofs; semi-automatic welders suitable for welding vertical surfaces and large angles; hot air asphalt welders specifically developed for flameless welding of modified asphalt membranes; and welding guns primarily for manual welding of various materials (Figure 5).
4.3 Non-perforated Welding Equipment
OMG, a US company, was the first to develop a non-perforated welding fixing system for single-ply roofing. Its earliest experimental application dates back to 1999 on a roof in Atlantic City, Georgia, USA. In 2009, OMG officially launched its electromagnetic induction welding system specifically for single-ply roofing at the IRE exhibition (Figure 6). That same year, OMG showcased this technology at the China International Building Waterproofing Exhibition in Beijing and began promoting it.
In addition to preventing puncture damage to the coil, non-perforated welding technology also allows for a more even distribution of fixings, improving the roof's overall wind resistance while also allowing for more flexible reinforcement options in corners. Furthermore, non-perforated fixings reduce wrinkles caused by coil deformation, resulting in a more aesthetically pleasing roof.
4.4 Development of Prefabricated Products
Tianjin Binhai Aotai Waterproof Materials Co., Ltd. specializes in the production and installation of PVC and TPO polymer waterproof membranes. Drawing on years of construction experience and drawing on international expertise, Aotai prioritizes waterproofing of detailed joints, developing systematic waterproofing research, production, and services. Over more than a decade of development, Aotai has launched specialized prefabricated waterproofing products for internal and external corners, pipe wraps, and downspouts using homogeneous (H-type) materials, gaining market recognition and acclaim.
In November 2014, Binhai Aotai invested in the establishment of Aokami Waterproof Technology (Tianjin) Co., Ltd., introducing advanced American processing technology and equipment to upgrade and expand its prefabricated product offerings. The company launched prefabricated system products compatible with the primary waterproofing material models, offering a full range of H, G, and P-type product lines, encompassing any size required by customers. This addresses issues such as poor welding compatibility and a limited number of specifications, while improving the system's mechanical strength and dimensional stability, rapidly gaining industry recognition.
In 2016, Aokami introduced digital production equipment, employing two- and three-dimensional computer-aided design. This paved the way for digitalization in product design and production, significantly improving production efficiency and product precision, resulting in more aesthetically pleasing products. To date, the company's prefabricated polymer waterproofing membrane system encompasses eight product lines: corners, pipe wraps, downspouts, exhaust systems, functional prefabricated components, underground projects, composite panels, and custom designs. Each line includes products in various shapes, suitable for various locations, and performing various functions, encompassing every aspect of waterproofing detail (Figure 7).
As polymer waterproof membranes are increasingly used in waterproofing projects, system waterproofing solutions based on prefabricated parts are also showing greater advantages and value in terms of quality and efficiency.
5. Reflections on the Successful Introduction of the Single-Ply Roofing System
5.1 Respecting Science and Learning from Others’ Strengths
my country has made significant progress in the research and application of building waterproofing materials over the past 40 years. However, compared with companies in developed countries like Europe and the United States, we still have much to learn in terms of new products and technologies. Faced with advanced foreign products and technologies, we have proactively reached out and invited them in, strengthening contacts, learning with an open mind, being open and inclusive, digesting and absorbing them, and standardizing and guiding the promotion and application of new products and technologies, thus promoting the high-quality development of my country's waterproofing industry. The introduction of the single-ply roofing system from abroad, from market cultivation and guidance to the establishment of a comprehensive system including standards and specifications, test methods, skills training, system components, and specialized contractors, has achieved international standards. It is a successful example of how the Chinese waterproofing industry can rapidly catch up and narrow the gap by learning from mature international experience.
5.2 Focusing on Quality is the Key to a Future
Quality is our credibility, our foundation, and our lifeblood. Innovation is driven by application, and application requires quality and technology to ensure it. Technology without quality is lifeless. We need quality and technology that is durable and can withstand the test of time. Single-ply roofing systems are exposed to direct use, and their quality will be directly tested by various external environments. This includes durability, wind resistance, and safety. There can be no room for ambiguity. Only by unwaveringly adhering to quality can we win the market.
5.3 Persisting in Innovation to Promote Development
The successful introduction of single-ply roofing technology has not only driven the rapid development of single-ply roofing systems in my country's waterproofing industry, but has also promoted the simultaneous development of related technologies. More importantly, it has fostered the establishment of an innovative development philosophy within my country's waterproofing industry. For enterprises to survive and thrive, they must persist in innovation. Especially during this period, when the waterproofing industry faces unprecedented challenges, enterprises must prioritize innovation, as only innovation can enhance their core competitiveness and help them escape the predicament of homogeneous competition.
