6.3.6 Air-termination systems for green roofs

Green roofs are a special type of construction in which the roof surface is covered with a layer of soil or substrate that allows plants to grow. They not only serve an architectural design purpose, but also perform technical functions such as thermal insulation, rainwater retention and improvement of the urban climate.
This results in specific requirements for lightning protection: On the one hand, the roof sealing must be protected against penetration, and on the other hand, personal safety must be ensured if the roof surfaces are accessible.

A basic distinction is made between two types:

• Accessible green roofs that are designed like parks with the intention of people spending time there.
• Inaccessible green roofs that primarily serve as thermal insulation and are not designed for foot traffic.

Regardless of the type of lightning protection system, no one should be on a roof when a thunderstorm is approaching. Signage and, where necessary, warning systems are therefore mandatory.

Accessible green roofs are characterised by their park-like design. Typical elements include paved walkways, seating areas, shrubs and, in some cases, also trees. These roofs are accessible to the public and are regularly used by people. This creates an increased risk of people being endangered in the event of a lightning strike.