# The Party Wall Act, explained for London homeowners > When your extension, basement or loft needs a party wall notice, who pays for the surveyor, and how to keep the process from delaying your build. A plain-English guide to the Party Wall etc. Act 1996. **Published:** 2026-07-09 · **Read time:** 8 min · **Category:** Process Party wall notices are where good London projects quietly lose weeks. Not because the Act is difficult, but because owners serve notice late, or assume it does not apply to them. On a terrace or a semi, most work to a shared wall, most new walls on a boundary, and most deep excavation near a neighbour triggers it. Miss it and your neighbour can stop your site. This is a plain-English guide for London homeowners whose extension, basement or loft is likely to touch a boundary. It covers what the Act catches, the notice periods that decide your start date, and how the surveyor process actually works. Every reference here is to the Party Wall etc. Act 1996 and the Government's published explanatory booklet on it. This is general guidance, not legal advice. A party wall surveyor advises on your specific facts, and on anything material you should take that advice before you act. --- The Act is a civil framework, separate from planning permission and Building Regulations. It does not grant or refuse permission for anything. It sets out how you must notify a neighbour about certain work, and how any dispute is resolved. Three kinds of work are notifiable. Work to an existing party wall, such as cutting in, raising it, underpinning or rebuilding. A new wall built up to or astride the boundary, which the Act calls the line of junction. And excavation near a neighbouring building. The excavation rule is the one that catches London owners by surprise, and it is where basements and deep foundations get caught. You must serve notice if you excavate within 3 metres of a neighbour's building or structure and go deeper than their foundations, or within 6 metres where any part of your excavation meets a line drawn downwards at 45 degrees from the bottom of their foundations. On a tight terrace, that captures most basement digs and a good number of ordinary extension foundations. The notice periods are fixed, and they drive your start date. Two months before work to an existing party wall. One month for a new wall on the boundary, or for an excavation notice. A notice stays valid for one year. Serve it too early and it can lapse before you build. Serve it too late and it holds up your start. This is why party wall notices belong in the programme from the first drawings, not once the contractor is already booked. > The Party Wall Act rarely stops a project. Served late, it routinely delays one. The difference is weeks, and it is entirely within your control. *[Image: HXL-delivered detached home with a new flank wall close to the site boundary.. Boundary work. A new wall on or near the line of junction is notifiable in its own right, on a one-month notice.]* When you serve a valid notice, your neighbour can consent to the work in writing, or dissent from it. If they do nothing for 14 days, the Act treats a dispute as having arisen. Dissent is not hostility; it simply moves matters into the surveyor process, which exists to protect both sides rather than to obstruct you. A neighbour can also serve a counter-notice within one month, asking for related work of their own. Once a dispute arises, the work is governed by surveyors. Either the owners agree on a single impartial figure the Act calls an Agreed Surveyor, or each owner appoints their own surveyor and the two select a third to hold the ring, called on only if the appointed pair cannot agree. These surveyors are not advocates for the person who appointed them. They are appointed under the Act to reach a fair outcome, and once an appointment is made it cannot simply be withdrawn. --- The surveyors produce a Party Wall Award. It records the work, how and when it will be done, the access required, and a Schedule of Condition. That schedule is a documented record of the neighbour's property before work starts, so that any later claim of damage is measured against fact rather than memory. It is the single most useful document in the whole process, and the one owners most often skip. Do not skip it. The costs usually fall to you, the Building Owner, including the adjoining owner's surveyor's fees, where the work is solely for your benefit. Surveyors' fees are not fixed, and you are entitled to ask for a breakdown if they look unreasonable. Once made, the award is final and binding unless a county court changes it on appeal, and each owner has 14 days from service of the award to appeal. Appeals are rare, and rarely worth the cost and delay. The practical rule is simple: identify party wall matters at design stage, not on site. The moment a scheme shows work to a shared wall, a wall on the boundary, or a deep excavation near a neighbour, the notice periods should already be in your programme. Talk to the affected neighbours early and informally, before a formal notice lands cold. Most party wall disputes are made worse by surprise, not by the work itself. HXL's role is to make the party wall process run in step with the build rather than against it. As principal contractor we sequence the works around the served notices and the award, give the surveyors the construction method and drawings they need to reach agreement, and hold the programme so that a neighbour's surveyor is never the reason your site stands still. The surveyors stay independent, as the Act requires; our job is to take the coordination risk around them off your plate. If your scheme is likely to touch a boundary or a neighbour's foundations, raise it with us at pre-construction stage, when planning for it still costs nothing. --- **HXL Construction Ltd** · Principal contractor and design & build firm · London and the Home Counties Email: info@hxlconstruction.com · Phone: +44 7845 585147 Registered office: 102 Vine Lane, Uxbridge, London UB10 0BE Canonical: https://hxlconstruction.co.uk/journal/party-wall-act-london-homeowners-guide