we had a lot of testing for your new siege weapon - trebuchet.
In its current state it destroys buildings and objects too fast(couple of hits). It is a major exploit, though its pretty much unstoppable.
In its current state buildings have the same HP basis, building's HP being dependant only on material quality.
For future vast siege implementation, you need to highly increase HP amount for fortification buildings.
Unless it is fixed, a trebuchet with a couple of people supporting its fire, can fully destroy a small fortress with stone walls in 1-2 minutes.
This feedback is solely based on in-game testing of trebuchet.