As of patch 1.4.1, below are the limits of the various planets:
- Haven: 2500m
- Alioth: 1300m
- Madis: 1460m
- Thades: 14709m
- Jago: 1300m
- Teoma: 1540m
- Sinnen: 1420m
- Sicari: 1600m
- Talemai: 2900m
For more information please see the following post: https://board.dualthegame.com/index.php?/topic/25630-static-construct-altitude-limit/