Party wall is filed in most people's minds under "extensions" — a thing that happens to houses when a neighbour digs a basement. It applies to flats too, and it applies in a way that catches owners out, because in a block the structure you share with your neighbour is frequently not beside you. It is underneath you.
This guide sets out the general shape of it for a flat refurbishment in Central London. It is not legal advice, and party wall matters have their own specialists for good reason. If there is any prospect that your works are notifiable, speak to a party wall surveyor before you finalise a programme.
What the Act is for
The Party Wall etc. Act 1996 provides a framework for certain types of work affecting shared structures and neighbouring land. Broadly it covers work to party structures, some excavation near neighbouring buildings, and the construction of new walls at a boundary. Where work is notifiable, the building owner must serve notice on the adjoining owners, and if consent is not given, surveyors are appointed and the matter proceeds to an award which regulates how the work is done.
It is worth understanding what the Act is not. It is not a veto for your neighbour, and it is not a planning system. It is a procedural framework designed to let work happen while protecting the adjoining owner's property and giving them a route to redress. A neighbour cannot simply refuse; a dissent leads to the surveyor process, not to a stop.
Equally, it is not optional. Proceeding with notifiable works without serving notice removes the protection the Act gives you as well as your neighbour, and can leave you exposed to injunction and to claims. The process exists partly for your benefit.
In a flat, the party structure is usually the floor
This is the point that reframes everything.
The Act deals with party structures, and a party structure can include a floor or partition separating buildings or parts of buildings approached by separate entrances or staircases. In a block of flats, the floor between you and the flat below can therefore be a party structure. So can the wall between you and the flat next door.
Which means a refurbishment that never touches a boundary wall in the ordinary sense can still be notifiable, because the works interfere with the floor. Cutting into joists to run a new waste, forming an opening, or altering the structure of the floor build-up may all engage the Act. Whether your specific proposal does is a judgement for a party wall surveyor on the facts, and this is exactly the sort of thing not to guess about.
Who your adjoining owners are
Another flat-specific trap. In a house, the adjoining owner is generally the neighbour. In a leasehold block, "owner" under the Act can extend to more than one person with an interest in the adjoining part — which in practice can mean both your neighbour and the freeholder.
The practical implication is that notice may need to go to several people, and identifying them properly matters. Getting the wrong parties served is one of the more common procedural failures, and it can undo the whole exercise. Your surveyor will advise on who must be served.
Where this shows up in real refurbishment work
- Bathrooms and kitchens moving. The waste has to reach the stack at a fall. In a shallow timber floor void that often means working on joists — and the joists are the floor. This is the most common route into party wall territory in a flat, and it is covered from the lease side in freeholder consent for a bathroom refurbishment.
- Removing internal walls. A wall that turns out to be doing structural work, or that turns out to be a party structure between flats.
- Forming openings. Through anything shared.
- Underfloor heating and new floor build-ups. Where they alter the structure rather than sitting on it.
- Chasing. Deep chasing into a party wall for services.
- Lowering or altering a lower ground floor. Excavation provisions can come into play, and this is specialist territory.
Not all of these are notifiable in every case. Some are clearly outside the Act, some are clearly inside it, and a fair number sit in the middle — which is why the surveyor exists.
Notices, dissent and awards, in general terms
Where work is notifiable, notice is served on the adjoining owners describing the proposed work. Statutory notice periods apply, and they differ depending on the type of work. We are not printing those periods here, because they are exactly the sort of detail that is misquoted with real consequences. Confirm them with a party wall surveyor.
The adjoining owner may consent, or may dissent. Dissent is not hostility — a surveyor will often advise a neighbour to dissent simply so that an award is produced and everyone's position is documented. Where there is dissent, surveyors are appointed and produce an award: a document setting out what may be done, how, when, and with what safeguards. A schedule of condition of the adjoining property is normally taken beforehand, which is as much protection for you as for them, because it is the evidence that the crack in their ceiling predated your job.
The building owner normally bears the reasonable costs of the process. What those are depends on the surveyors and the complexity, and we are not going to invent figures. Ask at the outset.
The timing problem
Party wall procedure takes time, and it is time you cannot compress by being keen. This is why it should be the first thing considered in a project rather than the last.
Worse, it runs alongside other processes that also take time and do not coordinate with it. In a Central London flat you may simultaneously need the freeholder's licence to alter under your lease — see licence to alter in a mansion block — plus planning or listed building consent if the fabric or exterior is affected, which is covered in conservation area rules in Central London and listed building consent for bathrooms. Building Regulations apply regardless — see building regulations for bathrooms.
Four separate processes, four separate clocks. Any contractor who gives you a start date before those are resolved is giving you a fiction.
What the schedule of condition is really for
Owners often treat the schedule of condition as a formality that delays the start. It is the most valuable document in the process, and it protects the person paying for it more than anyone else.
Old buildings are full of existing cracks, sloping floors, historic movement and tired plaster. The moment you start work below or beside someone, every one of those defects becomes, in their mind, something you did. Without a dated record of the property's condition before you began, that argument has no floor to stand on and you will lose it on sympathy alone. With one, it takes ten minutes to resolve.
The same logic applies to the works themselves. An award sets out how the work is to be carried out and what safeguards apply. Following it precisely is not bureaucracy; it is the thing that makes the adjoining owner's complaint answerable. Contractors who treat awards as advisory are the reason flats end up in disputes that cost multiples of the works.
Central London specifics
The stock makes party wall issues more likely, not less. Mansion blocks in St John's Wood, Maida Vale and Little Venice typically have timber floors of limited depth, which is precisely why waste runs end up interfering with joists. Converted terraces around Bayswater and Paddington are worse again: the conversions were often done long ago, structures were altered informally, and what is actually holding the building up is frequently not what the drawings say. Tight buildings in Mayfair, Marylebone and Fitzrovia add the further complication that a great deal of the stock is listed, so structural interventions carry heritage consequences as well.
There is also a human dimension worth naming. In a block, your adjoining owner is someone you will pass in the lift for years. Serving notice properly, taking a schedule of condition, and doing the work within agreed hours is not just legal hygiene — it is how you avoid a decade of froideur over a bathroom.
Sensible sequence
- Settle what you actually want to build, including the waste route and the floor build-up.
- Get advice on whether it is notifiable. Ask early; the answer shapes the design.
- Run the lease consent in parallel.
- Serve notice properly, on the right parties, in good time.
- Take the schedule of condition. Always.
- Build to the award and to the licence conditions, not to what is convenient on the day.
Where we fit
We build. We are not party wall surveyors and will not tell you whether your works are notifiable — that is a professional judgement with real consequences, and it should come from someone qualified to make it. What we do is work to the award and to the block's rules, with the protection, hours, access and waste arrangements they require, and tell you at quoting stage where we think a proposal is heading into structure that is not simply yours.
Our refurbishment work is quoted per project; bathrooms start from £2,800, with plumbing and electrical from £80. Send drawings or photos through the quote form or on WhatsApp for a fixed price.
This is general practical guidance, not legal advice. Take proper advice from a party wall surveyor before relying on anything here.