Roof waterproofing for existing photovoltaics on flat roofs

With an existing PV system, there are hardly any simple solutions for retrofitting the roof with waterproofing. For this reason, we show a typical example of the procedure for such a measure.

Unfortunately, for the repair of the roof surface, the complete PV system must be dismantled. It usually makes sense to refurbish the complete roof surface. The cost of disassembly and re-installation almost always justifies a complete refurbishment and includes leaks that were not detected during leak detection.

On this example roof, the PV support structure is connected to the roof by threaded rods. With this type of installation, the roof is penetrated with each threaded rod. Each penetration can leak in the long term. Even with proper craftsmanship, sealants can become brittle and no longer ensure sealing.

Renovating such a roof with conventional materials such as foils or bituminous membranes is almost impossible. Technically and economically, the most sensible solution is to use liquid plastic with a fleece insert, in this case the PURELASTIK product from ISOPOL.

In this process, Purelastik is applied with a fleece insert and each penetration is integrated into the waterproofing. The new waterproofing is seamless and adheres excellently to the substrate without additional additives (adhesives, screws).

We have documented the new construction of a PV system on an old roof here as an example.