If you live in a terraced or semi-detached house in Liverpool and underpinning has been recommended, the Party Wall etc. Act 1996 usually needs to be considered. Digging near or below a neighbour's foundations, or working on the shared wall itself, generally requires formal notice before work starts. A party wall surveyor handles the notices and, if needed, the surveyors' binding decision. We plan and carry out the engineer's scheme around those requirements. This page is general information, not legal advice.
Why does underpinning so often trigger the Party Wall Act?
Underpinning means taking a foundation deeper or transferring its load to firmer ground. In a detached house that is a matter between you, your engineer and Building Control. In a terrace or semi, the wall being underpinned may be the party wall, and even an external wall is likely to be within a few metres of next door. Merseyside has a great deal of this housing: dense Victorian terraces in Walton, bay-fronted terraces in Wavertree, inter-war semis across south and east Liverpool, and similar streets in Birkenhead, Widnes and St Helens.
The Act exists so that necessary building work can go ahead while the neighbour's property is protected and recorded. It is not a planning permission and it is separate from the Building Regulations approval that underpinning normally needs.
Which parts of the Act usually apply?
| Situation | Section | Minimum notice |
|---|---|---|
| Excavating within 3 m of a neighbour's building, deeper than the bottom of their foundations | Section 6 | One month |
| Excavating within 6 m, where the dig cuts a 45° line drawn down from the bottom of their foundations | Section 6 | One month |
| Work to the existing party wall itself, such as underpinning it, cutting into it or thickening it | Section 2 | Two months |
The figures above follow the commonly published summary of the Act (for example Nelsons' "Party Wall etc. Act 1996 – Made Simple"). If the neighbour does not respond within 14 days, a dispute is treated as having arisen and surveyors are appointed to settle it in a binding written decision. That document typically includes a schedule of the neighbour's property before work begins, the agreed method and working arrangements.
We are not party wall surveyors and we do not give legal advice. Whether and how the Act applies to your home is for a party wall surveyor to confirm. Talk to one early, because the notice periods sit on the critical path of the whole job.
How do we plan underpinning around a party wall?
- Design comes first. A chartered structural engineer decides whether underpinning is needed at all and, if it is, the method, depth, bay sizes and sequence. The surveyors need these details to assess the effect on next door.
- Notices and agreement. The party wall surveyor serves notices and, where necessary, agrees the surveyors' decision. We supply method statements and programme information when asked.
- Building Control. We submit the Building Control notice for the structural work, so the council or a registered building control approver can inspect at the stages they need.
- Services and access. Gas, water and drainage are located before digging. Shared alleys, rear entries and access through the house are agreed in advance.
- Work in stages. Excavation is carried out in short bays in a hit-and-miss sequence set by the engineer, so the wall is never left unsupported along its length. Each bay is inspected before concrete goes in.
- Record and close out. The neighbour's property can be checked against the schedule of condition when work finishes, and Building Control and the engineer sign off as applicable.
Does the method affect the party wall process?
It can. Mass concrete underpinning involves digging bays below the footing, which is the classic section 6 situation and may also be section 2 work if the party wall itself is underpinned. Mini-piled underpinning takes load down to deeper ground through small piles, and the piling, needles or beams may still involve excavation and work near the shared wall. Resin injection uses small holes rather than open digs, but it still alters the ground near the neighbour and the surveyors will want to understand it. The engineer chooses the method for structural reasons; the surveyors then consider its effect on next door.
Partial underpinning brings its own question. If only one side of a party wall, or only the front bay of one house in a terrace, is deepened, the junction between new and old foundations can become a "hard spot" where differential movement shows up. The engineer has to design for that, and the neighbour's surveyor will want to see how.
What about an insurance-funded repair?
If the underpinning is part of a subsidence claim, the insurer and its engineer decide the scheme, and the insurer's process normally includes the party wall arrangements. Our subsidence insurance claims page explains who decides what. When both neighbours are claiming for the same movement, the insurers usually need to coordinate, which can add time.
How does this affect cost and timing?
Party wall matters add surveyor fees and, above all, time. With one month's notice for excavation and two months for work to the party wall itself, plus any time to reach a surveyors' decision, several months can pass between design and the first dig. MyJobQuote's underpinning guide notes that approvals and party wall matters can add several months beforehand, while the work on site often takes around 3 to 5 weeks. Every job depends on the property, the method and the permissions. Our underpinning cost guide covers the wider cost factors.
What should you do now?
Talk to your neighbour early and openly; a calm conversation before formal notices often makes everything easier. Get the structural engineer's assessment so everyone is discussing the same scheme. Appoint a party wall surveyor in good time. If an insurer is involved, follow their lead. And do not start any digging or demolition near the shared wall until notices, agreements and Building Control are in place. Our wider underpinning service for Liverpool homes covers everything that happens once those pieces are ready.
Underpinning a terrace or semi?
Call 07777 659786 or send your details. Tell us the house type, which wall is affected and whether you have spoken to your neighbour, a surveyor or an insurer yet, and we will talk you through how a scheme for underpinning on Merseyside is usually planned.
Frequently asked questions
Do I need a party wall notice to underpin my house?
Very often, yes, particularly in terraces and semis. Under section 6 of the Party Wall etc. Act 1996, excavating within 3 metres of a neighbour's building and deeper than their foundations, or within 6 metres where the dig cuts a 45 degree line down from their foundations, needs notice. Underpinning usually needs to be considered against these rules. A party wall surveyor can confirm what applies.
How much notice does my neighbour need?
For excavation under section 6, at least one month. For work to the party wall itself under section 2, at least two months. Notices have to be served before the work starts, so allow for this in your programme alongside Building Control and any insurer approvals.
What happens if my neighbour does not reply to a notice?
If a neighbour does not respond within 14 days, a dispute is treated as having arisen. Surveyors are then appointed, either one agreed surveyor or one for each owner, and they settle matters in a binding written decision. That document usually records the condition of the neighbour's property and sets out how and when the work may be done.
Can the work go ahead if my neighbour objects?
The Act is designed to let necessary work proceed while protecting the neighbour. A neighbour cannot simply veto it, but the surveyors' decision can set conditions on working hours, access and methods. The detail is a matter for a party wall surveyor or a solicitor. We do not give legal advice and are not party wall surveyors.
Do you serve the party wall notices?
No. Notices and the surveyors' decision are handled by a party wall surveyor, or by owners who choose to serve notices themselves. What we do is provide the method, sequence and engineer's drawings the surveyors need, plan the programme around the notice periods, and work to whatever the agreement requires on site.