Underpinning in London – Secure, Correct and Engineer-Led
At KHB Piling LTD we help property owners, contractors and developers deal with one of the most serious issues in construction – loss of foundation stability. Our underpinning service is designed for London conditions: older housing stock, mixed ground, extensions added over time, nearby excavations and subsidence caused by clay movement.
We deliver underpinning, local excavation, basement preparation and associated foundation works for both residential and commercial buildings. Every project is assessed by our technical team first, so the method we propose is the one that actually solves the problem – not just hides the symptoms.
If you have cracking walls, dropping floors, doors that no longer close, or you are planning to load the existing structure with a new storey or basement – underpinning is the correct first step.
- the original foundation was too shallow for current use,
- ground conditions have changed (tree roots, drying clay, leaking drains),
- neighbouring works or basement digging have affected your structure,
- you want to add a rear/side extension or a basement under an existing house,
- you can see progressive cracking in walls or at window/door heads.
Without corrective underpinning, settlement usually continues and repairs become more expensive over time. Our approach is always: diagnose → stop movement → strengthen → record.
Last updated: 2026
Underpinning Methods We Use
Different buildings and different soils need different solutions. That’s why we don’t offer one single method – we match the technique to the building.
Mass Concrete Underpinning
The traditional, proven way. We excavate short controlled bays under the existing footing and fill them with reinforced concrete, one by one. Good for low to medium depth foundations and period houses.
Beam-and-Base Underpinning
We form concrete bases under the wall and link them with a reinforced beam that picks up and redistributes the load. Ideal when the existing foundation is uneven or we need to span services.
Mini-Piled Underpinning
Used where the good bearing strata is deeper or access is restricted. Small diameter piles transfer the load down to competent ground. Very useful in London basements and tight sites.
Raft / Slab Solutions
For buildings on very poor or variable soils we can form a new reinforced concrete raft that spreads the load over a wider area, reducing differential settlement.
Before we choose a method we review drawings, the condition of the existing footings, nearby structures and any available site investigation.
Why KHB Piling LTD?
Foundations aren’t the place to take chances. Here’s what sets us apart from other underpinning contractors in London:
- Engineer-led service – we don’t guess underpinning depth, we calculate it.
- London experience – we work every week on Victorian/Edwardian houses, party-wall conditions and sites with limited access.
- Measured, safe excavation – we only open as much of the foundation as can be supported that day.
- Documentation for Building Control – we issue records, concrete tickets and method statements.
- Co-operation with your architect/SE – we can work to your designer’s details or provide our own.
Typical Problems Underpinning Solves
Underpinning is not just for “old” buildings – it’s for buildings that are being asked to do more than they were designed for. Common triggers:
- cracks wider than 3 mm appearing or reopening,
- sloping or bouncing floors,
- visible movement at bay windows or rear extensions,
- manhole / drain failures causing local washout,
- planned basement excavation next to or under the house.
In each of these cases, stabilising the foundation first protects the rest of the structure and avoids repeat repairs.
Additional Foundation Services
Because we are a piling and groundworks company, we can deliver the whole package – not just the underpinning itself:
- site and ground investigation (to understand the cause of movement),
- mini piling and micro piling where deeper support is needed,
- basement excavation and forming retaining walls,
- load testing and as-built reporting,
- drain and service protection during works.
This means you deal with one contractor instead of coordinating several trades in a confined area.
Related services:
Mini Piling,
CFA Piling,
Basement Construction,
Ground Works.
If you suspect foundation movement or you are planning an extension on an older property, speak to us first. We can attend site, review the structure and advise on the most cost-effective underpinning method.
+44 7821 836407
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How Much Does Underpinning Cost in London?
Underpinning is priced per linear metre of wall, and the number that drives the price is depth – how far down we have to dig before we reach ground that will actually carry the building. On London clay that can be anything from 1.5 m to well over 3 m, and near mature trees it is usually at the deeper end.
- Mass concrete underpinning: around £1,000–£2,500 per linear metre
- Beam-and-base underpinning: around £1,500–£2,500 per linear metre
- Mini-piled underpinning: around £1,500–£3,000 per linear metre
Across the UK, a single wall or corner typically comes to £5,000–£15,000. London jobs tend to sit at the top of that range – spoil often has to come out by hand through the house, parking and skip licences cost more, and the ground is rarely straightforward.
What moves the price: the depth to good ground, access, how much has to be taken up and put back (floors, drains, patios), party wall surveyor fees, the structural engineer’s design and Building Control. Whole-house schemes and underpinning that forms part of a new basement need a proper design before anyone can give you an honest figure – be wary of a firm price given over the phone.
If the work is part of an accepted subsidence claim, the insurer normally pays for the investigation and the repair, and you pay the subsidence excess. Send us the insurer’s engineer’s report and we will price to that specification.
How Long Does Underpinning Take?
On site, one wall of a terraced or semi-detached house usually takes 2–4 weeks. Underpinning is done in short bays, around a metre at a time, in a hit-and-miss sequence: each bay is dug, concreted, left to gain strength and dry-packed tight to the old footing before the bays either side of it are opened. That sequence is what keeps the wall supported throughout the work, and it is the reason the job cannot be safely rushed.
Whole-house and basement underpinning runs to 8–12 weeks or more. Before any of that starts, allow time for the engineer’s design, Building Control approval and party wall notices, which must be served one to two months before work begins, depending on the type of work.
Alternatives to Underpinning – and When You Don’t Need It
We would rather tell you that you don’t need underpinning than sell you a job that won’t solve anything. A lot of movement in London houses comes from seasonal shrinkage of the clay or from a leaking drain softening the ground. Remove the cause and the building often settles down on its own.
- Fix the cause first. Have the drains CCTV-surveyed and repaired, and get an arboricultural report on nearby trees. If a tree has a TPO or you are in a conservation area, the council has to be involved before anything is cut back.
- Monitor before you dig. Crack monitoring over several months shows whether movement is ongoing or just seasonal. Insurers often insist on it before agreeing a repair.
- Crack stitching. Once the movement has stopped, helical bar stitching and repointing may be all the wall needs.
- Resin (geopolymer) injection. Expanding resin is injected through small holes to strengthen the ground under the footing. It is quick and clean and works for some shallow settlement, but it is less predictable where trees are drying the clay at depth, and it won’t help if the foundation genuinely needs to go deeper.
- Mini-piled needle beams or a piled raft. Where good ground is a long way down, putting the load onto mini piles is often cheaper and less disruptive than digging traditional underpinning to 3 m or more.
Underpinning is the right answer when the existing foundation is simply too shallow for the ground it sits on, when movement carries on after the cause has been dealt with, or when you are adding load – an extra storey, a loft conversion or a basement. In those cases, doing it properly once costs less than filling the same cracks every few summers.
Testimonials
KHB Piling stabilised our property after movement was spotted. Clear method, tidy work, would recommend.
Ezekiel Browning · Google review
Professional underpinning team in London – good communication with our architect and Building Control. Five stars.
Grzegorz G · Google review
They explained the options (mass concrete vs mini-piled underpinning) and helped us choose the right one. Smooth process.
Corety · Google review
We were building in London on tricky ground. KHB’s underpinning and piling package gave us confidence to continue the project.
Aleksandra Dabek · Google review