Single-Layer Roof Technology Awakens Polymer Waterproof Coiling Materials Market   

By Niu Guangquan, China National Building Waterproof Association

Single-layer roof refers to roof system paved with single layer. Compared with traditional multi-layer roofs paved with three or four layers of paper-padded asphalt felt, single-layer roof uses less materials and can help save more energy, has longer service life and is more convenient to pave. It represents the development trend of roof waterproof materials and technologies.
   Suitable materials include modified asphalt waterproof coiling materials and polymer waterproof coiling materials. Modified asphalt waterproof coiling materials are mostly modified by styrene-butadiene-styrene elastomer (SBS) and atactic polypropylene resin (APP) and have multiple layers of asphalt. However, they are not very serviceable and are falling out of use. Polymer waterproof coiling materials include many different varieties such as ethylene propylene diene monomer rubber (EPDM), butyl rubber, polyvinyl chloride (PVC), thermoplastic polyolefin (TPO), chlorosulfonated polyethylene (CSP), ethylene copolymers modified bitumen (ECB), polyisobutylene (PIB), chlorinated polyethylene (CPE) and ethylene/vinyl acetate copolymer (EVA). Varieties that work well in roofs are EPDM, PVC and TPO.
   China has fully realized the necessity of developing single-layer roof in recent years and already adopted measures and policies to promote their development. The Ministry of Housing and Urban-Rural Development of China has issued an announcement to promote EPDM and PVC waterproof coiling materials in house construction. The single-layer roof technology in China has also started to develop.
   China can already manufacture production equipment for EPDM waterproof coiling materials. Through technical renovation the annual capacity has already increased from 600 000 square meters to more than 1 million square meters. Remarkable progress has been achieved in the key technology of adhesive jointing. Some Chinese enterprises have developed good quality adhesives used for coiling materials. Self-adhesive tapes marketed in recent years are convenient in installation and can guarantee the quality of installation. The width of coiling materials made in China is also increased. China is able to produce coiling materials with a width of 6 meters, which is good for large roofs. The average installation fee of EPDM coiling materials is, however, RMB58.61 per square meter as compared to an average installation fee of RMB26.19 per square meter for ethylene - propylene fiber double sides composite coiling materials. However, China only produces homogenous EPDM coiling materials. Reinforced EPDM coiling materials are inadequate here. Attached materials are also yet to be enriched and developed.
   The quality of PVC coiling materials produced in China has improved remarkably improvement. Years ago, China’s production lines could only produce coiling materials with a width of one meter. Most new production lines can produce 2-meter width materials today. Double-layer interior-reinforced PVC waterproof coiling mats have also been developed by some Chinese companies with the product quality reaching the world advanced level.
   TPO waterproof coiling materials have already been used in some major projects in China. Some domestic enterprises have constructed production lines of TPO waterproof coiling materials, with some production lines able to produce 3-meter width materials.
   Roof waterproofing should also develop toward low carbon emission. For example, white reflecting roofs coated with white acrylic reflecting coatings should be advocated. EPDM layers should be capped with stone materials to extend their service life.
   China today consumes little EPDM waterproof coiling materials. The product variety is limited. Greater efforts should be made to develop reinforced and back-lined varieties and acquire more complete matched products. Both in terms of energy conservation or cost reduction and in terms of application dissemination effort, loose paving systems capped with stone materials or block materials should be put in the development agenda.