Do I need a Party Wall Agreement for my House Extension in London?

When embarking on a house extension project in London, where we mainly operate, we often get asked by our clients if they need a party wall agreement? Many don’t even know what a party wall is or what a party wall agreement is… just that it’s something they need.

So, we thought we’d start at the very beginning …


What is a Party Wall?

A party wall is the shared wall, usually between a terrace or semi-detached house, and divides the homes of two separate owners. It may also include garden walls built over a boundary and excavations close to a neighbour’s property (within three or six meters, depending on the depth of the new foundations). Party wall Awards or Agreements are most commonly needed for building projects that involve loft conversions, basement excavations, internal renovation and extensions.


What is a Party Wall Agreement?

The Party Wall Award or Agreement is a legal document that is drawn up by the two-party wall surveyors or by a single surveyor (if he/she is are acting on behalf of both the Building Owner and the Adjoining Owner or the neighbour). The aim of the Party Wall Award is to resolve any disputes between neighbours as a result of a building project of the one of the neighbours.


The Party Wall Award essentially consists of three parts:

  • The Award or Agreement that states how and when the building works are going to be carried out.


  • The Schedule of Conditions – This is an important part of the Award. It is a detailed record of the current condition of the adjoining property. This will include recording existing issues such as cracks, staining, holes, decay, discolouration, leaks and other defects, disrepair or deterioration along with accompanying photographs. The party wall surveyors will then undertake a re-inspectionof the building after building works have been completed to determine whether any damage has occurred as a result of the building work and whether any repairs need to be carried out.


  • Structural drawings of the proposed works.


The Award must also clearly state the names and address of the Building Owner or Owners and the Adjoining Owner/s names and addresses as listed in the land registry or Company House records in the case of a UK listed company along with details of the surveyor or surveyors.


What else should be included in the Award?

Working hours – e.g. 9:00am – 5:00pm

Proof of the builder/contractor’s public liability insurance

Any indemnities for the Adjoining Owner or neighbour

Clarification of any damage and the steps that will be required to rectify them

Access arrangements to the adjoining owner’s property

Adjoining Owner’s or neighbour’s surveyor’s fees

Costs to be paid by an Adjoining Owner or neighbour for contributing towards the cost of repair to a party structure.

Agreed compensation to paid to the Adjoining Owner or neighbour

Security arrangements

Noise considerations


Usually, the Award is initially written out in a draft format and made final once both parties have agreed on the details. There is a 14 day right to appeal if either owner feels something is amiss, however, this is usually rare, as most of the issues are likely to have been ironed out before the Award is finally drawn up and legally signed and witnessed by the appointed surveyor(s).


How long is a Party Wall Award valid?

A Party Wall Award is valid for 12 months from the date of its service. This would mean that the building owner must commence the proposed works within 12 months of the date of the Party Wall Award.


Do you need a party wall agreement?

If you share a wall with your neighbour i.e. your property is a semi-detached or a terraced property, you will need to draw up a party wall agreement with your neighbour. If your property is detached, you may still need a party wall agreement if your property is within three to six metres of your neighbour’s external wall. This is also dependent on the depth of your foundation. Party wall Awards are important to avoid from unnecessary disputes and conflict between neighbours.


What happens if a neighbour reports damage to his or her property because of my extension?

The first step is to appoint a party wall surveyor… You may have already done this if you appointed a party wall company to draw up your agreement.


Once the appointed party wall surveyor(s) have been notified there are three possible routes to go down, all at the choice of the neighbour.


  1. Perhaps the most amicable route is when the building owner and the adjoining owner discuss and agree on a course of action without engaging the appointed party wall surveyor(s). In this scenario you and your neighbour agree between yourselves on arrangements for the damage to be made good or for a financial compensation to be made.


  1. The appointed surveyor(s) identifies the scope of the repair works by cross-referencing the pre-works condition report and a written schedule of repair works is drawn up and agreed between them. Your neighbour agrees for your contractors to undertake the repair work scoped by the appointed surveyor(s). Your neighbour may also request that the appointed party wall surveyor(s) confirm that repairs have been carried out satisfactorily on completion.


  1. The third route is as point 2 however instead of carrying the repairs you agree to pay your neighbour a financial compensation based on determination made by the appointed surveyor(s). Your neighbour can then choose to appoint their own contractor to carry out the works at their convenience.


The SDA Build London team know that this is a complicated area. We work closely with reputed party wall professionals who will be able to advise you on the best way forward for your particular home extension project. Given that most of our projects are in Chelsea, Kensington, Battersea, Fulham and surrounding areas where the majority of homes are semi-detached or terraced, we understand the importance of Party Wall Agreements.


Give us a call on 0208 191 7595 or email us at to discuss how we can help.