WATERPROOF MEMBRANES | MATERIALS


He said that in Germany, the green roof market


grew by 141% between 2008 and 2022 – and is now growing at around 7% per year. The global green roof market exceeded US$12 billion in 2023 and is expected to grow to three times that size by 2033, he said. “The greenroofer is the waterproofer’s best


friend,” he said. A green roof acts as a protective shield, which


can extend the lifespan of a waterproofing layer by up to 200%, he added. “Both green roofers and waterproofers bring unique skills and knowledge to a project and this ultimately leads to higher client satisfaction,” he said. A green roof is typically built from a series of layers that includes a waterproofing layer, a geotextile ‘filter’ and a water retention layer. This is then topped with some form of vegetation. These can be combines with solar panels to create ‘biosolar’ roofs. In similar fashion, Dirk Van Kerckhove of Embuild – the Belgian construction association – said that ‘climate roofs’ (including green roofs and energy roofs) can help Europe to meet climate change targets. “Roofs are unused surfaces with high potential,”


he said. There are various ‘categories’ of roof, including


‘green’ (technically durable), ‘red’ (multifunctional, or for recreation), ‘yellow’ (less CO2 production) and ‘blue’ (for circularity). Embuild – as part of the Klimaatdak project – is working on a series of standards and targets for such roofs. These include: insulating all new flat roofs, to obtain energy neutrality by 2030; and ensuring every new flat roof contributes to ‘green’ and ‘blue’ infrastructure by 2030.


Flexible roofing Michael Fischer, technical service account manager atWestlake Vinnolit in Germany, presented details of an inherently flexible polymer for roofing membranes. The idea behind the product, he says, is to raise technical performance to meet strict regulatory requirements. The company has also developed an ‘inherently


flexible blend’. Benefits include: high durability – with no cracking


or embrittlement; resistance to fats and oils; good scratch and abrasion resistance; improved haptics – with no plasticiser on the surface; no stickiness or staining; and superior weatherability. The inherently flexible polymer, called Vinnolit


VP 401, is vinyl chloride grafted onto a polyacrylate for a final PVC content of 35-50%. The final com-


www.filmandsheet.com


pound combines the polymer itself with several additives. It comes in the form of a free-flowing powder, and is available in several different Shore A grades. Its inherently flexible blend is a grafted copoly-


mer (Vinnolit K 707 E) with a flexible EVA polymer called Levamelt from Arlanxeo. The two have good compatibility, creating a flexible blend with no monomeric plasticiser. Shore A of the copolymer itself is around 90, but this can be modified by adding EVA. The company has carried out tests to compare the two grades with more traditional offerings (PVC plus plasticisers). Traditional grades lost more mass over 14 days due to evaporation of plasticiser – leading to loss of mechanical properties. The same was true when stored in oil. The tensile strength of the traditional grades also increased over 14 days – due to plasticiser loss – while the two new grades remained constant. “The inherently flexible grades had superior


storage resistance and more constant mechanical properties,” according to Fischer. “They are inert to other polymers and also have no plasticiser migration.” n AMI’s Polymers in Roofing conference is held in Brussels, Belgium on 18-20 November 2025. For more details, contact Pranita Nangia on +44 (0) 117 311 1519 (pranita.nangia@amiplastics.com).


CLICK ON THE LINKS FOR MORE INFORMATION: � www.solmax.com � www.renolit.com � www.carpitech.com � www.amiplastics.com � www.converde.eu � www.embuild.be � www.klimaatdak.be � www.westlakevinnolit.com


May 2025 | FILM & SHEET EXTRUSION 35


Above: The green roof market could to grow to three times its current size by 2033


IMAGE: SHUTTERSTOCK


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