Is It Legal For My Upstairs Neighbor In A Two Unit Home To Have Access To My Basement That's Connected To My Part Of The House.

They keep shorting their power by using space heaters that's overloading the electricity because their heat is turned off (unknown reason) . Just wanting to know if it's legal or not as it makes me uncomfortable and maintenance told me I have no choice but asked if it was okay if they made a key for him. GRAND RAPIDS MI. The door connected to the basement leads straight into my kitchen and is an arms length from my bedroom.

The door from outside is my back door that goes straight into my basement and the second door is a arms length across going into my kitchen , their excuse is theirs a deadbolt on my door to the basement.