When planning a house extension in Sussex, party wall matters are worth addressing early. Doing so can reduce delays, avoid misunderstandings, and help keep relationships with the people next door on good terms. Under the Party Wall etc. Act 1996 ( applicable in England and Wales ), certain building works require you ( the building owner ) to serve formal notice on the adjoining owner, the legal term for the owner of the neighbouring property that could be affected by your works.
A “party wall agreement” is often used as shorthand for the process under the Act. Where surveyors become involved, the outcome is typically a Party Wall Award. This is not paperwork for its own sake; it is a formal framework that records what work is proposed, how it will be managed, and what should happen if damage occurs. It can also deal with practical points such as access to the adjoining owner’s land where that access is necessary for the works.
This guide explains when the Act applies to home extensions, the main notice types, what happens if an adjoining owner does not respond within the statutory time limits, and how surveyors and a schedule of condition protect both parties.
Understanding party wall agreements (what the Act requires)
A party wall agreement is the everyday term for the statutory procedure set out in the Party Wall etc. Act 1996. In practice, there are two common routes:
- Written consent from the adjoining owner (meaning surveyors may not be required), or
- A dispute is treated as arising, leading to the appointment of surveyor(s) and the production of a Party Wall Award.
The Act is typically relevant where extension works involve either:
- Work to a party wall or party structure (for example, cutting into a shared wall for beams), or
- Excavations close to an adjoining owner’s building, which may affect foundations.
Using correct legal terminology helps avoid a basic but common problem: a notice being served on the wrong person, or the wrong notice being used for the proposed works.
Overview of the Party Wall etc. Act 1996 (England and Wales)
The Party Wall etc. Act 1996 provides a statutory procedure for certain building works that could affect a shared wall, boundary, or nearby foundations. It applies in England and Wales. While the Act itself is the same, local practice and professional expectations can vary, so projects in Wales ( in particular ) may benefit from advice from a party wall surveyor familiar with the local area.
At a practical level, the Act is built around:
- Advance notice to the adjoining owner
- A route to agreement (consent, or the surveyor process)
- Protection for both parties, typically including a record of the adjoining property’s condition and clear rules for how the works should be carried out
TTypes of notice you may need for an extension
The notice you serve depends on the works proposed. For party wall agreements for extensions, the most common notices are:
- Party Structure Notice: for works directly affecting a party wall/party structure (for example, inserting beams into a shared wall or raising a party wall).
- Notice of Adjacent Excavation: for excavations within the distances set by the Act and to a depth that could affect the adjoining owner’s foundations, often relevant for extension footings.
It is possible for one extension project to require more than one notice, especially where structural works and new foundations are both involved.
Notice periods and the 14-day response rule
Once a notice is served, the adjoining owner has 14 days to reply.
- If they provide written consent, you can usually proceed ( subject to other approvals such as planning permission and building control ).
- If they do not respond within 14 days, they are deemed to have dissented. Silence is treated as a dispute arising, which triggers the surveyor appointment procedure. The surveyor(s) then produce a Party Wall Award setting out the permitted works and protections.
This point is frequently misunderstood. From a programme perspective, the “deemed dissent” rule is one reason party wall matters should be addressed well before the intended site start date.
Party wall considerations on common house extension types
Many projects in West Sussex and the wider Sussex area involve extension layouts that naturally bring works close to boundaries. Examples include:
- Rear extensions: new foundations and drainage runs can be near the adjoining owner’s structure.
- Side return extensions ( common in period terraces ): the extension line often sits close to the boundary, increasing the likelihood of excavation notices.
- Wraparound extensions: these frequently combine boundary-adjacent excavation with structural alterations.
- Double-storey extensions: structural sequencing and temporary works may heighten adjoining owner concerns even where the notice type is straightforward.
Whether you are a homeowner, architect, contractor, or investor, the key is to identify party wall triggers during design and planning, rather than treating them as a site-start formality.
Notification process (how to serve notice properly)
Serving notice begins the statutory process. The notice should be accurate, clear, and served in a way you can evidence.
- Identify the correct adjoining owner
The adjoining owner may not be the occupier. For rented property, for example, notices usually go to the owner (freeholder/leaseholder), not the tenant. - Use the correct notice type(s)
Match the notice to the works ( Party Structure Notice and/or Notice of Adjacent Excavation ). - Include sufficient information
A notice typically describes:
- the nature and purpose of the works
- the property address and building owner details
- an indicative start date
- drawings and method information where helpful (particularly for excavation and structural details)
Allow the adjoining owner time to respond
After 14 days, non-response is treated as dissent and the surveyor procedure begins.
(Party Wall etc. Act 1996, 1996)y do not respond within 14 days, they are deemed to have dissented, and the surveyor procedure begins.
Serve the notice and keep records
Keep copies and proof of service. If timing or service is disputed later, this documentation becomes important.
Access to the adjoining owner’s land
For certain works, the Act grants the building owner a right of access to the adjoining owner’s land where access is necessary to carry out the notified works, provided reasonable notice is given and inconvenience is minimised. On extension projects, access issues commonly arise with scaffolding, weatherproofing at junctions, or making good near the boundary. Addressing access early can prevent avoidable conflict.
If there is a dispute: surveyors, awards, and the schedule of condition
If the adjoining owner dissents ( or is deemed to have dissented due to non-response ) surveyor(s) are appointed. Each party can appoint a surveyor, or both can agree on one Agreed Surveyor.
The surveyor’s role
Party wall surveyors act impartially under the Act. They assess risk, set protections, and produce a Party Wall Award that commonly covers:
- the scope of works permitted
- working methods and sequencing where relevant
- access arrangements and conditions
- procedures for dealing with damage and making good
Schedule of condition
Before works start, surveyor(s) usually prepare a schedule of condition for the adjoining property (often notes plus dated photographs). This creates a baseline record and helps manage disagreements fairly if damage is alleged later.
Practical compliance points for extension projects
Where access is likely, address it early and formally.
Identify party wall triggers during design and planning.
Serve notice on the correct adjoining owner and keep evidence of service.
Avoid starting works that fall under the Act until written consent is received or (where required) a Party Wall Award is in place.
Working with an extension specialist in Sussex
If you are planning an extension close to a boundary, it helps to have a team that can spot party wall triggers early and coordinate information between design and construction.
Contact Apex Lofts And Construction today to discuss your extension plans and the practical steps needed before work begins.
Conclusion
Party wall procedures are a common part of many house extension projects in England and Wales. Understanding when the Party Wall etc. Act 1996 applies, serving notice on the adjoining owner, and respecting the 14-day response period can prevent avoidable delay.
Where consent is not provided, the surveyor process and a schedule of condition provide a structured way to protect both parties and allow the extension works to proceed with clear conditions set out in a Party Wall Award.