Party wall agreements in London: notices, surveyor costs and what happens if a neighbour says no

What the Act covers on a typical London job

The Party Wall etc. Act 1996 is not about planning and not about building control. It is a procedure for work that affects a wall you share with a neighbour, a wall on the boundary, or their foundations, and it applies whether or not you have planning permission. On a London terrace it is in almost every structural job. The Government's explanatory booklet lists the most common rights under section 2: cutting into a party wall to take the bearing of a beam, for example for a loft conversion; underpinning the whole thickness of a party wall; raising it; extending it downwards for a basement; inserting a damp-proof course; and cutting off projections such as a chimney breast.

A party wall, for the Act, is a wall that stands astride the boundary, whether it is part of one building or separates two, and also a wall that stands wholly on one owner's land but is used by both to separate their buildings. The Act uses the wider term party structure for floors and partitions between flats approached by separate entrances, so a flat above a flat is in scope too. A garden wall astride the boundary is a party fence wall; a fence is not.

The three notices and their periods

A party structure notice, under section 3, covers work to an existing party wall or structure and must be served at least two months before the work begins. A line of junction notice, under section 1, covers a new wall on or at the boundary and needs one month. A notice of adjacent excavation, under section 6, covers digging near a neighbour's building and needs one month, and it must be accompanied by plans and sections showing the site and depth of the excavation. A party structure notice and an excavation notice cease to have effect if the work has not begun within twelve months of service (sections 3(2) and 6(8)). A line of junction notice has no such rule, though the right to put footings under the neighbour's land under section 1(6) only runs from one month to twelve months after service. So do not serve a notice a year before you are ready.

There is no official form. A valid notice gives your name and address, the address of the building, a full description of the proposed work with plans where they help, and the intended start date, and it is dated and says it is a notice under the Act. You can serve it yourself, by hand, by post or by email if the neighbour has agreed to email; the Government's booklet includes example letters for each type. Every adjoining owner gets one, which means the freeholder and any leaseholder of the flat next door, and on a mid-terrace usually both sides.

What the neighbour can do: consent, dissent, or nothing

A neighbour who receives a party structure notice or an excavation notice can consent in writing, dissent, or ignore it. Under section 5 (section 6(7) for an excavation notice), if they have not consented in writing within 14 days they are deemed to have dissented and a dispute is deemed to have arisen. Silence is therefore a dissent, which surprises people on both sides of the wall. Within one month of a party structure notice the neighbour can also serve a counter notice under section 4, asking for additional or modified work for their own benefit, and the building owner has to comply unless it would be injurious, cause unnecessary inconvenience or delay.

What a neighbour cannot do is stop the work. The booklet is explicit that an adjoining owner cannot prevent someone exercising the rights the Act gives them, but may be able to influence how and when the work is done. Written consent does not release the building owner from the duties in the Act either: under section 7 you must not cause unnecessary inconvenience, you must protect the neighbour's building where you lay it open, and you must compensate the adjoining owner and occupier for any loss or damage the work causes.

Agreed surveyor or two surveyors

Once a dispute has arisen, section 10 gives two routes. Both owners can concur in appointing one agreed surveyor, or each appoints their own and the two surveyors immediately select a third, who is called in only if they cannot agree or either party calls on them. A surveyor is anyone who is not a party to the matter; the booklet adds that they should not already be engaged to supervise the building work, should know construction and the Act, and that you cannot act for yourself. The surveyors settle the matter by an award that sets out the work, when and how it is to be carried out, any additional protection required, usually a schedule of condition recording the neighbour's property before the work starts, and access for inspection during it.

The award is conclusive and binding. Either owner can appeal to the county court within 14 days of it being served, and the booklet warns that an unsuccessful appeal can carry costs. For a straightforward loft or extension the agreed-surveyor route is usually faster and cheaper; the two-surveyor route is the one to expect when the neighbour is anxious, the works are a basement, or the relationship is already poor. Keep a copy of the award with your deeds.

What it costs and who pays

The Act sets no fees. Under section 11 the expenses of work under the Act are met by the building owner except where the Act says otherwise, and under section 10 the surveyors decide who pays the costs of the award and of inspecting the work; the booklet's summary is that the building owner usually pays all of it, including the neighbour's surveyor's fees, where the work is solely for the building owner's benefit. The exceptions are repair work to a defective wall, which is shared in proportion to use and responsibility, and additional work a neighbour asks for. Surveyors have to be paid their reasonable costs, and either owner can ask for a breakdown of hours and rates.

Published London figures for 2026 put an agreed surveyor, or a single award, at £700–£1,800 per adjoining owner. Where the neighbour appoints their own surveyor the building owner pays two sets of fees, and London surveyors quote £1,400–£4,500 per neighbour for those cases, with basements at the top. A mid-terrace loft with steels into both walls therefore carries two neighbours' worth of fees, which is why the notice, the conversation over the fence and the offer of an agreed surveyor are worth more than any other paperwork on the job. Those are market figures from published guides, not our quotes; our loft conversion cost guide shows where they sit against the build cost.

If a neighbour dissents, or ignores you

A dissent, or silence for 14 days, starts the dispute procedure; it does not stop the job. Propose an agreed surveyor. If the neighbour refuses to concur in one or to appoint their own, section 10 lets you serve a request, and if they still neglect to appoint for ten days you can appoint a surveyor on their behalf so the procedure proceeds without them; the booklet describes exactly this. If the neighbour's own surveyor refuses to act, or ignores a request for ten days, section 10 lets your surveyor proceed alone on that matter as if they were the agreed surveyor. The award then sets the terms and the work goes ahead under it. What you cannot do is start without serving notice at all: the Act contains no enforcement mechanism of its own, but a neighbour can go to court for an injunction to stop unnotified work, and the delay and cost of that dwarf the fees you were avoiding.

Access works the same way. Under section 8 an adjoining owner and occupier must let your workmen and surveyors in where that is necessary for work under the Act, on 14 days' notice except in an emergency, and it is an offence to obstruct someone entitled to enter. The right only covers the notified works, so scaffold on the neighbour's side for something outside the Act, such as rendering your own wall, is a matter of agreement. A neighbour can also ask for security for expenses before you start, so that a job abandoned halfway does not leave their wall open.

Timing it into a London programme

Serve the notices when the structural drawings exist, not when the scaffold is booked. Two months is the minimum for a party structure notice and the neighbour is not obliged to let you start earlier even after agreeing the works; a dispute adds the surveyors' time on top, and a schedule of condition needs access to the neighbour's rooms before the first brick moves. In practice the party wall period is usually the longest single wait on a loft or an extension, longer than the structural work it precedes, which is why we serve at design stage and price the fees as a line the client can see.

Can you write your own party wall agreement?

Yes. If your neighbour consents in writing to a valid notice within 14 days there is no dispute, no surveyor is required and the notice plus the consent is the agreement. The booklet says plainly that you do not need a professional adviser to serve a notice, and its example letters are written for exactly this. Two things are worth doing even when everyone is friendly: keep the notice, the consent and the drawings together, and agree a photographed record of the neighbour's wall and ceilings before you start, because a crack noticed a month later is far easier to settle against a record than against memory. If the work is a basement or a full chimney stack, a surveyor's schedule of condition is money well spent regardless.

Selling a house without a party wall agreement

There is no register of party wall awards and no certificate that has to exist for a sale, but a buyer's solicitor will ask whether any works to a party wall were carried out and whether the Act was complied with, and an honest no is a negotiating point for the buyer. Where a job was done without notice and the neighbour has never complained, there is nothing to put right retrospectively under the Act itself; the exposure is a neighbour who raises damage later. Keep whatever exists, the notice, the consent or the award, with the building control completion certificate for the same works, and hand the file over.