The Party Wall Act and structural works: a practical guide

When does the Party Wall Act apply?

The Party Wall etc. Act 1996 applies in England and Wales when you carry out certain work to a wall shared with a neighbour, build a new wall on the boundary line, or dig foundations close to a neighbour's building. You must serve written notice on the adjoining owners before starting. Work to an existing party wall needs two months' notice, while a new wall on the boundary or a nearby excavation needs one month.

The Act does not stop you building. It sets out a process that protects both owners, resolves disagreements through surveyors and requires the building owner to put right any damage the work causes. It runs alongside planning and Building Regulations, not instead of them. Having planning permission or Building Control approval does not remove the need for notice.

Notice goes to every adjoining owner. That includes the freeholder of the neighbouring property and, in many cases, leaseholders with longer leases, so a converted house next door can mean several notices. Checking ownership at the Land Registry before serving avoids missing someone.

The three types of notice

Each notice covers a different kind of work, and a single project can need more than one:

• Party structure notice: work to an existing party wall, such as cutting in beams, underpinning, raising the wall or removing a chimney breast. Two months.
• Line of junction notice: building a new wall on or astride the boundary line. One month.
• Notice of adjacent excavation: digging within 3 m of a neighbour's structure and below its foundations, or within 6 m where the dig cuts a 45 degree line from their foundations. One month.

What a valid notice needs

Each notice must describe the proposed work clearly. Excavation notices must also include plans and sections showing where the new foundations will go and how deep they will be. A notice that is vague or incomplete can be challenged, which wastes time, so it is worth getting right first time.

The notice periods are minimums. With the neighbour's written agreement, work can start sooner. A notice also lapses if the work it describes has not started within a year, so serving notices too early can backfire on a long project.

Which structural works typically need notice

In London terraces and semi-detached houses, the shared wall is the obvious place to support new structure. That is why so many everyday projects fall under the Act:

• Loft conversions with steel beams bearing into the party wall, or the wall raised for a dormer or hip-to-gable
• Knocking two rooms together with a new beam on padstones in the party wall
• Removing a chimney breast built into the party wall
• Rear extensions with foundations close to, or on, the boundary
• Underpinning or basement excavation next to a neighbour's foundations
• Cutting into the party wall to insert flashings for a new roof

What happens after notice is served

The adjoining owner has 14 days to respond. They can consent, or dissent and ask for matters to be settled by surveyors. If they do not reply within 14 days, a dispute is treated as having arisen. Where there is a dispute, the owners either appoint one agreed surveyor to act for both, or one surveyor each. The surveyors then make a party wall award, which sets out what work can be done, how and when, and records the condition of the neighbouring property. The building owner normally pays the surveyors' reasonable costs.

The Act also gives the building owner a right of access to the neighbour's land where it is needed to carry out the notified work, on giving proper notice. In return the work must not cause unnecessary inconvenience, and the building owner is responsible for making good any damage it causes.

Talking to your neighbours before anything arrives in the post helps. Show them the drawings, explain the timetable and answer their questions. Our guides to loft conversions and chimney breast removal are useful background for those conversations.

Our role: structural engineers, not party wall surveyors

We are structural engineers. We do not act as party wall surveyors, either appointed or agreed, and we do not draft party wall awards. What we provide is the engineering and paperwork the process depends on.

For building owners, our party wall notices and schedule of condition service, from £550 + VAT, covers advice on which notices are needed, preparation of the notices and a photographic schedule of condition of the neighbour's property before work starts. If a dispute arises, the matter passes to party wall surveyors, and our designs give them what they ask for: beam and padstone calculations, underpinning sequences, foundation sections and temporary works method statements.

For adjoining owners or their surveyor, our party wall structural review checks the neighbour's drawings and calculations, assesses the effect on the shared wall and your home, and sets out clear technical questions for the building owner's engineer.

Why a schedule of condition matters

A schedule of condition is a dated, photographic record of the relevant parts of the neighbour's home: cracks and their widths, damp stains, uneven floors and anything else that could later be blamed on the work. It is taken before work starts and shared with both sides.

Without one, every crack found after the works can become an argument. With one, it is easy to show which defects were already there and which are new. If new damage does appear, the building owner must make good or pay compensation, and the schedule turns that into a factual exercise. Make sure it covers the rooms against the shared wall, the rear wall near any extension, and garden walls close to the work.

When the works finish, the neighbour's property is inspected again and compared with the original record. Any new or worsened cracks are noted, and the repair or compensation is agreed on that basis. Keeping the schedule with your project file is worthwhile, as it may be needed months later.