Protective fleece or building protection mat for protecting the roof cladding?

Photovoltaic systems on rooftops pose a challenge when it comes to protecting the roof. The two common methods are the use of protective fleece or traditional building protection. We compare the two approaches and discuss the recommendation of the German Roofing Trade Association (ZVDH).

When installing photovoltaic systems on flat roofs, the question of how to effectively protect the roof cladding arises time and again. The two common methods, the protective fleece and the traditional building protection mat, differ in key aspects.

Adaptability

Protective fleece with tuck-in flaps cover the corners of the load-distributing base plates of the mounting system and thus prevent damage to the roof cladding. They are not bonded and adapt to thermal expansion. A bonded building protection mat / EPDM mat cannot provide this equalisation. At high temperatures, it can creep at the bonding point and shift permanently. This results in protruding sharp corners.

Risk analysis

Building protection mats harbour risks such as plasticiser migration, an increased area exposed to wind and a lower coefficient of friction with the aluminium lamination. These factors can impair the effectiveness and longevity of the roof protection – they do not occur with a fleece.

In its flat roof guidelines, the German Roofing Trade Association recommends the use of plastic fleeces for PV roof installation. This is why we at Schweizer also rely on the protective fleece for our flat roof systems.

By the way: Our nonwoven for the MSP-FR flat roof system has successfully passed the demanding test for ageing resistance in accordance with DIN EN 1297. It has withstood 6,000 hours of rapid ageing due to UV radiation, increased temperature and water without any problems.