short question.

does anyone know at what form of change on a rented house i do need to inform/ask the landlord ?

i plan to install a small door for my Cats trough the wall (about 20 x 20cm hole required)

of course that will be fixed prior moving out, the question is just if there is a regulation for this kind of things?

I'm not sure the regulation, but why would you not talk to your landlord about anything you want to alter? Better before than problems later.

Of course talk first is the right aproach.

I just asking as a result of a conversation i had a few days ago.

Easiest way to provide a swing door for your pet is a made-to-order door panel replacing an external side door panel. At the end of your lease, replace it with the original door panel.

No messing around with repairing holes in walls, plastering and repainting.