There are a number of issues that can cause concern to a house or flat owner when neighbours initiate building work, including:

• structural stability

• intrusions over boundary lines

• garden walls

• trees

A Party Wall Agreement is designed to remove uncertainty and aims to ensure that disputes do not arise. A Party Wall Agreement may also be drawn up whenever a neighbour proposes excavation development within 3 metres (about 10 feet) of the common boundary. In some cases where deep excavations are proposed, this can extend to 6 metres.

Party Wall Agreements are separate from the provisions and requirements of Planning Permissions and Building Regulations.

The initiator of all work covered by the Acts concerned has an obligation to serve a Notice on his neighbours, and if no such Notice is given it can be demanded. If work commences without one, then an injunction can be obtained to halt work until the correct procedures are followed.

An Agreement is not obligatory if all parties are in agreement that it is not needed.

The Agreement, or Award, is drawn up by party wall surveyors. Each party appoints their own independent surveyor (who can also be an architect or engineer) who will draw up the documents; the two surveyors will then come to an agreement, which is legally binding. Sometimes a single surveyor can be jointly appointed, but unless work is clearly uncontentious, this is not recommended.

The appointment of a professional, who has experience of party wall matters, is recommended.

The documents will usually establish the condition of each property before work starts, mitigating arguments later if cracks or other defects occur. Drawings and specifications are usually attached, and in many cases structural calculations are required.
There will also be conditions on when and how work can proceed: working hours, noise, intrusion, clearance of rubbish. If work must extend over the boundary, for example for access or scaffolding, then the conditions for this are established. An adjoining owner has some degree of right to this, but it must be established as a necessity.

All costs of a Party Wall Agreement should be paid entirely by the developing site owner.