Many residential projects require a party wall agreement. Please refer to follwing link for more information.The Party Wall Act (1996)
If you intend to carry out building work which involves one of the following categories:

• Work on an existing party wall or party structure or building against such a party wall or party structure
• ​Excavating near a neighbouring building

You must find out whether that work falls within the Act. 
If it does, you must notify all adjoining owners and you may need party wall agreement.

You will not be alone in this process. We, at AVA Home Design, will guide you through it and ensure it is completed to the highest standard