Party wall

Very often the wall in this case is non-structural but designed to meet established criteria for sound and/or fire protection, i.e. a firewall.

While party walls are effectively in common ownership of two or more immediately adjacent owners, there are various possibilities for legal ownership: the wall may belong to both tenants (in common), to one tenant or the other, or partly to one, partly to the other.

[2] Apart from special statutory definitions, the term "Party Wall" may be used in four different legal senses.

Originating in London as early as the 11th century, requirements for terraced houses to have a dividing wall substantially capable of acting as a fire break have been applied in some form or other.

The wall starts at the foundation and continues up to a parapet, creating two separate and structurally independent buildings on either side.