A gravel flat roof covering around 6’600 m² means primarily one thing: a lot of space on which the gravel must be evenly placed in its place. In Avenches, we have used our Power Jumbo pneumatic roller to transport the gravel to the roof and distribute it over the designated areas. The gravel protects the roof structure there and is also used to ballast the PV construction.
Pneumatic gravel delivery to the roof area
With approximately 6,600 m² of roof area, material logistics is an essential part of the construction process. The gravel was therefore transported directly onto the flat roof from the vehicle with our Power Jumbo pneumatic conveyor system via the conveyor line.
The material could then be distributed in the designated areas on the roof. This eliminated additional transport routes with smaller containers and a large part of the manual shifting on the roof.
Why a gravel flat roof is a good idea
The screed layer forms the visible finish of the roof construction when installed on a pitched roof and protects the underlying waterproofing from direct UV radiation and mechanical impacts. At the same time, it reduces the excessive heat generated by an open roof waterproofing system.
When precipitation falls, the water first hits the gravel and, through the interstices of the gravel, reaches the intended roof drainage. The gravel must therefore be installed in such a way that drainage channels and paths remain free.
Sand-filled roof as ballast for the PV construction
In Avenches, the gravel also performs a function in the photovoltaic system. It is used as ballast for the supporting structure.
On a flat roof, when there is strong wind, forces act on the PV modules and their supporting structure. Depending on the system, these forces can shift or lift the structure. The additional weight of the gravel counteracts this and keeps the designed structure in place.
The amount of ballast required at each location is determined during the planning of the PV system. This takes into account, among other things, the roof geometry, the substructure, and the prevailing wind loads.
With its area of around 6,600 m², the gravel plays a role not only in the construction of the roof, but also in the intended ballasting of the PV structure.
Power Jumbo for large-area roof work
This way, the conveyor technology was directly integrated into the workflow on the roof area. The gravel reached the intended installation areas directly and could be processed there without any additional handling.
After the work is completed, the gravel layer remains a permanent part of the gravel flat roof. It protects the sealing and also performs the planned ballastation of the PV structure.
