Most people are either unaware of the Party Wall Act, or unclear of the details. The Party Wall Act covers the protection of neighbours from work that may affect their property. There are a few examples of what a Party Wall actually is: a party wall can be a shared wall in a semi-detached property or a garden wall on a boundary line. The most common time a Party Wall Agreement is required is when an extension or new dwelling is proposed close to a neighbouring boundary.
The Party Wall Act itself is a very powerful piece of legislation that protects homeowners from any kind of negative impact on their property in the case where a neighbour carries out construction works. This most often occurs when a construction operation impacts the integrity of foundations of existing property, that property may then experience settlement or subsidence due to the new loading and effects of new elements.
This impact is exactly what the Act tries to limit, avoid completely or at least assign legal protection in the case in which something happens in the future.
If you are intending to do any traditional building work within 3 metres of the boundary with a neighbour it is your responsibility to agree terms with that neighbour. This should be done at the earliest opportunity so that you can avoid any unnecessary legal issues. If you do not approach your neighbour, they are entitled to come to you to address the situation and at that point they may involve Party Wall Specialised Legal teams and these can be chargeable to you directly, not the neighbour!
You can find more guidance on your responsibilities by following this link