What Is a Party Wall Agreement and Do You Need One?
Introduction
The phrase "party wall agreement" comes up regularly in conversations about home extensions, loft conversions, and basement projects — but many homeowners aren't clear on what it actually involves, whether it applies to them, or what happens if they ignore it.
This guide explains the Party Wall etc. Act 1996, what triggers the requirement to serve notice, what a party wall agreement involves, and what your options are as a building owner.
What Is a Party Wall?
A party wall is a wall shared between two properties — typically the wall between two terrace houses, or the wall between a semi-detached house and its neighbour. The term also covers:
- Walls that sit on the boundary line between two properties, even if not structurally shared
- Floors or ceilings that divide sections of a building (common in flats and conversions)
- Garden walls on or beside a boundary
The Party Wall etc. Act 1996 applies to work that affects a party wall or the land near a boundary — not just to walls that are literally shared.
When Does the Act Apply?
The Act applies in three main scenarios:
Works to a party wall or party structure. This includes: cutting into a party wall (for example, to install beams), raising or lowering a party wall, demolishing and rebuilding a party wall, or underpinning a party wall.
Excavation near a neighbour's property. If you're digging foundations within 3 metres of a neighbouring building, and the excavation goes deeper than their foundations, the Act applies. If within 6 metres and digging below a 45-degree angle from the neighbour's foundations, notice is also required.
New building at the boundary. If you're building a new wall at or astride the boundary line between two properties, notice must be served.
Does a Rear Extension Trigger the Party Wall Act?
Not always — but it depends on the specific works.
A standard rear extension built entirely within your own property and not involving any shared walls or close excavation may not trigger the Act. However:
- If the extension requires foundations closer than 3 metres to a shared boundary and is deeper than the neighbouring foundations, notice may be required under Section 6
- If the extension involves cutting into a shared wall or a wall on the boundary, the Act applies
- If you're building close to a shared flank wall and work could affect it, the Act is likely relevant
The safest approach is to check with a party wall surveyor before assuming the Act doesn't apply.
What Does Serving Notice Involve?
As the building owner (the person carrying out the work), you must serve written notice on the adjoining owner at least one or two months before work begins, depending on the type of work.
The notice must set out what work you intend to carry out and when. The adjoining owner (your neighbour) then has 14 days to either:
- Consent in writing — in which case work can proceed without a formal agreement
- Dissent — in which case a Party Wall Award (the formal agreement document) must be produced by a party wall surveyor
What Is a Party Wall Award?
A Party Wall Award is a legal document produced by an agreed surveyor (appointed jointly by both parties) or by two independent surveyors (one for each party). It sets out:
- What works are permitted
- The schedule of condition of the neighbouring property before works begin
- Any restrictions or requirements on how the work is carried out
- Arrangements for access to the neighbouring property if required
The Award protects both parties. If damage occurs as a result of the works, the schedule of condition provides clear evidence of what was there before.
What Happens If You Don't Serve Notice?
Failing to serve notice before carrying out notifiable works is a breach of the Act. A neighbour can seek an injunction to stop the works, and you may be liable for damages. In practice, many disputes arise after the event when damage is discovered and there is no schedule of condition to reference.
Serving notice is a simple process and the costs involved (surveyor fees where required) are a small fraction of the risk exposure if you don't.
Need advice on whether the Party Wall Act applies to your project?
RCB Design & Build advises clients on their obligations before works begin and can recommend a party wall surveyor where needed. Contact us to discuss.
📞 07359 872594 | contact@rcbgroup.co.uk | www.rcbgroup.co.uk