Party Wall Agreements in Prime London: When a Neighbour Objects or the Plans Change

A party wall agreement settles what you may build. What to do when a neighbour objects, or when your plans change after the notice.

A party wall agreement is rarely the hard part of a London house. The hard part comes afterwards: a neighbour who will not sign, or a design that moves on while the paperwork stays where it was. Both are common on streets where almost every house shares a wall, a foundation or a boundary with someone who has advisers of their own. This piece looks at those two moments, and at how to get changes made without losing months of programme.

We have written separately about how to approach the neighbour before anything is served. Here the question is what happens when that goes less smoothly than hoped.

What a party wall agreement actually settles

People speak of a party wall agreement, but the Party Wall etc. Act 1996 gives two routes. The neighbour consents in writing, or a dispute arises and surveyors settle it by a document called an award. Either way, what is agreed is the work described in your notice, and nothing else.

The notice periods are set out in the government’s explanatory booklet. Work to an existing party wall needs at least two months’ notice. A new wall at the boundary, or excavation near a neighbour’s foundations, needs at least one month. A notice is valid for a year. The adjoining owner has 14 days to respond, and if they do nothing in that time, the booklet says a dispute is deemed to have arisen.

That last point surprises people. Silence is not consent. It is the start of the formal process.

When the neighbour does not agree

A dissent, or silence, sends the matter to surveyors. Under section 10 of the Act, the two owners either agree on one surveyor or each appoints their own, and those two select a third. Appointments are made in writing. The surveyors then settle by award whatever is in dispute: the right to carry out the work, when and how it is done, and who pays the costs.

Where the works are for the building owner’s benefit alone, the booklet says the building owner will pay all costs. An award can be challenged by appeal to the county court, but the window is short: 14 days from service of the award.

In our experience, a neighbour’s dissent on a prime London street is more often procedural than hostile. Their advisers want the protections the Act provides, and a formal award is the tidiest way to get them. A building owner who understands that tends to find the process quicker than expected. One who treats it as an obstruction tends to find it slower.

One of those protections is security for expenses. An adjoining owner can ask for it before work starts, in the form of money, a bond or insurance, and the booklet notes it is usually reserved for particularly intrusive or complex works. On a deep basement, we would rather offer it than wait to be asked.

Protecting the house next door

Before work begins, the surveyors normally record the condition of the neighbouring property. The booklet says a schedule of condition is not a requirement of the Act, but that it is “most prudent”. It is also what makes any later claim answerable: without it, deciding what the works did and what was already there becomes a matter of recollection.

The building owner is responsible for making good any damage caused by the works, even where a contractor caused it. That is a fair rule, and a reason to treat the record seriously. The houses on either side of a prime London project often carry finishes as fine as anything being made for the client: silk wall coverings, water-gilded cornices, polished plaster, pictures hung on the shared wall. A schedule written by someone who knows what they are looking at is worth far more than a generic one.

When the plans change after the notice

This is where programmes are lost, and it is the question we are asked most often once a project is under way.

An award should confine itself to the work described in the notices, according to the booklet. So a design change that stays within what the notice described is a matter for the surveyors to note and, if necessary, reflect in the award. A change that goes beyond it may need further notice or a further award. A deeper excavation, an additional storey, the removal of a chimney breast, a revised structural scheme: these are the changes most likely to move outside the original description. The booklet does not say in terms whether such a change needs a fresh notice, so this is a point to take to your party wall surveyor before drawings are issued, not after the contractor has started.

The adjoining owner can also move the goalposts. After a notice for work to a party wall, they have one month to serve a counter-notice setting out additional or modified work they would like carried out. If the neighbour is planning a project of their own, it is better to learn that before the scheme is fixed.

There is also the simple matter of time. A notice lasts a year. On a listed house, or a street where a great estate’s licence is needed, the consents can take longer than the notice allows, and a project can outrun its paperwork without anyone noticing.

Our own practice, and it is a matter of judgement rather than law, is to settle the scheme before anything is served, and then to treat the notice as a boundary around the design. Each revision is read against the wording of the notice before it is issued. If it falls outside, the party wall surveyor is asked first and the programme is adjusted in the same conversation. Relevant detail on the wider consent process is in our piece on the true cost of a Grade II listed renovation, and the excavation notice is part of every deep-basement scheme, which is covered on our basement extensions page.

A calmer way through

The practical lesson is a modest one. Decide the scheme properly, describe it carefully in the notice, record the neighbour’s house with care, and keep one person responsible for checking every later change against what was served. For those weighing a purchase with major works in mind, Clarity, our pre-purchase appraisal service, is the natural place to start the conversation.

This article is general information, not legal advice. The detail of the Act, particularly where a design changes, should be confirmed with a party wall surveyor or a solicitor who knows it well.