The Act recognises two main types of party wall.

Party wall type A

A wall is a “party wall” if it stands astride the boundary of land belonging to two (or more) different owners.

Such a wall:

• is part of one building
• or separates two (or more) buildings
• or consists of a “party fence wall”

A wall is a “party fence wall” if it is not part of a building, and stands astride the boundary line between lands of different owners and is used to separate those lands (for example a masonry garden wall). This does not include such things as wooden fences or hedges.

Party wall type B

A wall is also a “party wall” if it stands wholly on one owner’s land, but is used by two (or more) owners to separate their buildings.

An example would be where one person has built the wall in the first place, and another has built their building up against it without constructing their own wall.

Only the part of the wall that does the separating is “party” – sections on either side or above is not “party”.

The Act also uses the expression “party structure”. This is a wider term, which could be a wall or floor partition or other structure separating buildings or parts of buildings approached by separate staircases or entrances for example flats.

Walls that are not Party Walls:

These may include boundary walls (a fence wall/garden wall built wholly on one owner’s land) and external walls (the wall of a building built up to but not astride the boundary).