In Partnership With Zinco

Walkways on Roofs

Driveways for Cars

Driveway for Lorries

General Information Regarding Paving Slabs on Roofs and Garage Roofs

Rooftops are being used holistically at an ever increasing rate. And this makes sense: everything that can be planted at ground level can also be planted on a rooftop. The correct technology must be applied to ensure that paving slabs built on rooftops are durable and function correctly.


In contrast to landscaped rooftops, where the flow of water has to be delayed or held back, when it comes to paving slabs on rooftops, the majority of the rainwater has to drain off the surface. Drainage points must, therefore, be planned so that two levels of drainage are possible: at both the drainage level and the surface level. The ZinCo product range provides the necessary system superstructures and accessories.


The flat roof guidelines and DIN 18195 stipulate a minimum gradient of 2% for the waterproofing level, but they also regulate for working with lesser gradients. “Stilted paths” can be built without a surface gradient, because the rainwater can drain off through the gaps: this means that standing water is not a problem. Concrete or asphalt flooring should be built with a gradient of at least 1.5%; paved flooring with a gradient of at least 2%. If possible, the area should not be drained in the direction of the building. This should, therefore, be considered during the preliminary planning stages.

The Most Common Usage of Rooftops: A Combination of Paths and Landscaping

If a combination of paving slabs and landscaping is desired, then the construction must have a high capacity for water retention, as well as drainage capabilities and resistance to compression. With Floradrain® FD 40 as the centre-piece of the construction, all requirements for a long-lasting functionality are fulfilled. Depending on the laying procedure, it will either hold the water back or let it through. Particular attention should be paid to the transitions between the paving slabs and the landscaping during the planning and implementation stages.


Driveways on rooftops require both a stable construction and that the rooftop construction has an adequate load-bearing capacity. If the structures cannot withstand heavy loads then many rooftops that have driveways will have warnings regarding the load limitations, e.g. maximum permissible axle load of lorry up to 3.5 tonnes. If these limitations apply, the construction can, in some circumstances, be “streamlined”. As wheel loads lead to enormous concentrated loads due to their relatively small surface area, sufficient load distribution has to be available. This can be achieved through the use of load-distributing plates or through sufficiently thick substrata.


Steering, braking and accelerating on driveways can lead to enormous horizontal forces being created. In order to direct these forces away from the waterproofing of the roof, measures such as laying slide bearings may be required. The forces are then contained by stable surrounds.

Stone Thickness

The stone thickness should be selected in accordance with the loads. Lesser loads, e.g. cars only, do not require the paving to be as strong as with higher loads. In cases where both cars and lorries are used, the rolling structural loads can lead to perversions.

Selecting a larger stone thickness will result in a larger bearing surface between the stones, which will do more to counteract perversions

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