Exactly what I was going to say. [NB - based on experience with English letting contracts: check if you're going to use it] Legally, they're supposed to give you at least 24hrs notice before they arrive on the premises. I can imagine that it might be difficult to say exactly that, as they're also your housemate's parents, but 24hrs notice of any specific landlord-y activity is more than reasonable. The law does stress that it is your home, and I think student landlords tend to forget that, as many students continue to see their parents' house as 'home'. However, that doesn't change their obligations to allow you to live in peace. They own the building (and maybe the furniture) but they have explicitly allowed you the use of it, for money. This applies also to complaints about 'messiness' - they should not technically be able to see it without notice. Unless they have asked you, for good reason, to put certain furniture in certain places, it should be entirely between you and your housemate unless you damage something.