When it comes to outdoor courts, there are two solutions;
SoftBase which is an asphalt surface (draining) with a concrete frame around (where the construction is screwed). Inside the frame, drainage work is carried out, macadam is laid to finish with 4-7 cm of asphalt.
HardBase which is a concrete sole, which is cast and which is similar to the same surface / foundation that is most common indoors.
The SoftBase is gentler for the players and NOT least it ensures that the rain disappears from the course in the shortest possible time (more games - more revenue). Note that in warmer countries (with temperatures above 35 degrees for a while) we do not recommend SoftBase.
The hard base needs to be made with falls, so that the water can get out of the track. The HardBase gives a feeling more like the indoor track, as both have concrete.
As a third alternative, a hard-packed base of stone flour is mentioned, and it is an alternative that we can not recommend as we have bad experience of just that type of solution. But with guarantees from the person who does it, this should be feasible, and what contributes to the interest in this solution is that it is cheaper.
In 2021, alternatives to those we recommend have emerged. Examples of these alternatives are and the experiences / views we have are: