What type of sub-base is ideal for ECCOgravel gravel mats, and what is the minimum height of this sub-base?

The required height depends on the application: with or without vehicle traffic.
For applications without vehicles or with frequent pedestrian traffic, it is recommended to install a sub-base of crushed limestone or porphyry (0-32 mm or 0-40 mm) with a thickness of 20 to 30 cm. For applications with vehicles, the sub-base should be 30 to 50 cm.
On top of the sub-base, a leveling layer is placed, using crushed limestone or porphyry (2-4 mm or 1-3 mm) or screened sand. For applications without vehicles, the leveling layer should be 10 to 15 cm, and for applications with vehicles, 5 to 10 cm.