Do I need to provide a minimal slope to buffer the rainwater?

Unlike concrete paving blocks or surfaces, ECCOgravel requires no minimum slope. Even with very heavy rainfall, the buffering capacity will be sufficient to handle the rainwater.

A quick calculation: the maximum 20-yearly rainfall in Belgium is 270 l/s/ha. For 10 minutes, this corresponds with 16.2 l/m².

The rainwater will immediately flow in between the hollow spaces of the gravel and the underlying foundations. This way, we reduce the risk of a reduction in functionality of the surfacing due to water remaining on the surface. A gravel layer of 5 cm may store up to 10 liters of water. It goes without saying that a minimal gravel foundation will take care of the rest.