Answer:
a party wall easement.
Step-by-step explanation:
A party wall is a dividing wall between two adjoining buildings that is shared by the occupants of each residence or business. A party easement however is a contract that binds both parties from the above from destroying the wall without consensual agreement, giving each party title to one half of the wall(the part facing each party's building) and some sort of coming interest in the adjoining wall.