Rooftops are being used holistically at an ever increasing rate. Nearly everything that can be realised on the ground is now possible on roofs too, provided the right technology is used. For instance, long lasting and functioning walkways and driveways on rooftops require well-engineered systems. These assure the continuance of the roof functions (e.g., waterproofness, drainage, thermal and sound insulation) and cater for horizontal forces generated by accelerating, breaking and steering.
General Information on Rooftop Walkways and Driveways:
As opposed to landscaped rooftops where water is to be held back and run-off is to be delayed, walkways and driveways need most of the rainwater to be quickly drained off the surface. Hence, the drainage points should allow for 2 levels of drainage: at the surface level and at the lower drainage level. The ZinCo product range provides the necessary system superstructures and accessories to cater for this.
The flat roof guidelines and DIN 18195 determine a minimum gradient of 2% for the waterproofing level, but they also regulate constructions with smaller gradients. “Stilted paths” can be built at 0° slope, as the rainwater is drained away through the interstices ; standing water is therefore no issue. Concrete or asphalt flooring should be built with a minimum slope of 1.5%, paved flooring with a gradient of at least 2%.
What is more, the drainage of the relevant area should not be done in the direction of the building. All this must be considered in the preliminary planning stages.
If walkways and driveways are combined with Green Roofs, not only the drainage and the compressive strength of the system are important, but also its water retention capacity. With Floradrain® FD 40-E as core element of the construction, all requirements are fulfilled for a long-lasting functionality. Depending on its laying procedure, FD40-E will either retain water or let it pass through. Particular attention during planning and implementation should be paid to the transition areas between the paving slabs and the landscaping.
Driveways on rooftops require both a stable construction and adequate load-bearing capacity. 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 substrates.
In the case of rooftop driveways,the paving stone thickness should be selected in accordance with the loads. Lesser loads (e.g. cars only), do not call for the paving to be as strong as if used with higher loads. When both car and lorry traffic occur, the rolling structural loads can lead to distortions. Selecting a larger stone thickness will result in a larger bearing surface between the stones, which will do more to counteract distortions.
Steering, breaking and accelerating on driveways can lead to enormous horizontal forces being created. In order to direct these forces away from the roof’s waterproofing, measures such as laying slide bearings may be required. The forces are then contained by stable surroundings.