Party Wall may be used in 4 different legal senses

“party fence wall” means a wall (not being part of a building) which stands on lands of different owners and is used or constructed to be used for separating such adjoining lands, but does not include a wall constructed on the land of one owner the artificially formed support of which projects into the land of another owner;

“party structure” means a party wall and also a floor partition or other structure separating buildings or parts of buildings approached solely by separate staircases or separate entrances;

“party wall” means—

(a)a wall which forms part of a building and stands on lands of different owners to a greater extent than the projection of any artificially formed support on which the wall rests; and

(b)so much of a wall not being a wall referred to in paragraph (a) above as separates buildings belonging to different owners