Party Wall

Definition in s20 of the Party Wall Act

“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;

UK Government Guidance

The gov.uk Guidance Note provides that 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 (see diagram 1)
• or separates two (or more) buildings (see diagram 2)
• or consists of a “party fence wall” (see diagram 3)

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 (see diagram 4).

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 are 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 (see diagram 5).

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).