09 / 15 Construction & conversions
A building is only as good as what it stands on. Many London homes are built on clay, which moves as it wets and dries, and many older houses sit on shallow foundations. As foundation contractors in London, we use piling to give new extensions and buildings a deep, stable footing on difficult ground. We use underpinning to strengthen existing foundations that have moved, or to deepen them for a basement.
All foundation work follows a design by a structural engineer and is inspected by building control. Our team also carries out the building work above ground and the repairs afterwards, so a foundation job does not leave you with a cracked, unfinished house.
Our services
We install mini piles to support new foundations where normal strip foundations would have to be very deep. Typical situations are clay near trees, soft or made-up ground, and sites with restricted access. Piles are drilled, driven or screwed into firm ground, then tied together with pile caps and ground beams.
See our piling contractors page
Underpinning strengthens or deepens the foundations of an existing building. It is used when subsidence has damaged a house, or when a floor is being lowered for a basement. Depending on the building and the ground, it is done in short sections of concrete, with beams and bases, or with mini piles.
See our underpinning contractors pageNot sure which?
Every house is different — we check what suits yours before you commit to anything.
Book a free site visitDifference
Piling usually creates new foundations for something being built. Underpinning repairs or deepens the foundations of a building that already exists. Mini piles can also be used as a method of underpinning.
| Piling | Underpinning | |
|---|---|---|
| Used for | New extensions, new builds, garden buildings on poor ground | Existing buildings affected by subsidence, or lowering floors for basements |
| What it does | Transfers the load down to firm ground through piles | Extends existing foundations deeper, to firmer or more stable ground |
| Common methods | Bored, driven and screw mini piles, with pile caps and ground beams | Mass concrete, beam and base, and mini-piled underpinning |
| Typical trigger | Ground investigation shows deep or unstable soil, or trees nearby | Movement confirmed by an engineer, or a basement design |
London clay
It can. Much of London sits on London Clay, a shrinkable soil that loses moisture and shrinks in dry weather, then swells again when it is wet. If a house has shallow foundations, this seasonal movement can cause cracking. The risk is higher near trees and large shrubs, whose roots draw moisture out of the clay. Removing a large tree can cause the opposite problem, called heave, as the clay swells back.
Clay is not the only cause of movement. Leaking drains can wash away or soften the soil under a foundation, and poorly compacted ground from earlier building work can settle. Finding the cause matters, because it decides whether underpinning is needed at all.
Warning signs
These signs suggest the foundations should be investigated:
Many cracks are harmless: fine cracks in new plaster, or cracks from normal shrinkage, can simply be repaired by filling cracks in walls. Only a structural engineer can confirm subsidence. Often, the engineer monitors the cracks over a period before recommending anything.
Not always underpinning
No. Many cases of subsidence are stopped by dealing with the cause, without underpinning. That might mean removing or managing a tree, or repairing a leaking drain found with a CCTV drain survey and fixed through our drain repairs and lining service. Once movement has stopped, the cracks can be repaired. Underpinning is usually recommended when the movement continues or the foundations are clearly inadequate.
If you suspect subsidence, contact your buildings insurer early, as subsidence is often covered by buildings insurance. The insurer usually appoints its own engineer to investigate. We work to the engineer's design, whether the work is an insurance claim or privately arranged.
What you need to know
Where used
Foundation work is often part of a bigger project. House extensions on clay near trees often need piled foundations. Basement conversions usually need the existing walls underpinned before the floor is lowered, and new builds on poor ground may be piled throughout. Because we carry out these projects ourselves, the foundations and the building above are planned together.
Cost
Every job is priced from the engineer's design and a site visit, and you receive a written, itemised quote. The main factors are:
Mass concrete, beam and base, or piled underpinning, and the type of pile.
The number of piles, or the length of wall to be underpinned.
How far down firm ground is.
Restricted access may need smaller rigs, hand digging or work from inside the house.
Soft ground, water in excavations or nearby trees.
Crack stitching, plastering and redecorating.
Structural engineer, ground investigation, building control and party wall surveyors.
No guesswork: you receive a written, itemised quote after your free survey, with payments staged against clear points in the work.
Process
Every stage is planned before we start, with one project manager from survey to sign-off.
we look at the property, the access and any damage, and review the engineer's report if you have one.
trial pits or ground investigation, then a structural engineer's design.
building regulations approval and party wall notices.
protecting the house and garden, setting up safe access, and any temporary supports.
underpinning in sequenced sections, or installing piles, pile caps and ground beams, with building control inspections.
crack repairs, then plaster patch repair and redecoration.
building control completion and the documents you need for your records and insurer.
Areas
We carry out piling and underpinning across London, with a focus on east and south-east London, where clay soils, mature street trees and older, shallow-founded houses make foundation work common. See our pages for piling contractors in London and underpinning contractors in London, or find us as builders in Ilford, builders in Barking, builders in Dagenham, builders in East Ham and builders in Orpington.
FAQs
Can't see your question? Call or WhatsApp us — we're happy to help before you book.
Piling creates new foundations by driving or drilling piles down to firm ground, usually for new extensions and buildings. Underpinning strengthens or deepens the foundations of an existing building, for subsidence or a basement. Mini piles can be used as one method of underpinning.
Warning signs include diagonal cracks wider at the top, cracks that reopen after filling, sticking doors and windows, and gaps between an extension and the house. Only a structural engineer can confirm subsidence, and many cases are solved by removing the cause rather than underpinning.
It depends on the method, the length of wall, the depth of firm ground, access and the repairs needed afterwards. We price each job from the structural engineer's design and a site visit, with a written, itemised quote.
It can. London Clay shrinks when it dries and swells when it gets wet, so shallow foundations can move, especially near trees. Leaking drains are another common cause of movement.
If you suspect subsidence, yes. Subsidence is often covered by buildings insurance, and the insurer usually arranges an engineer to investigate. We can carry out the repair to the engineer's design.
Yes. All piling and underpinning must be designed by a structural engineer and approved under the building regulations. We can work with your engineer or help arrange one.
One team, every trade
Next step
Tell us about the cracks you have noticed or the project you are planning. We will visit, look at the property and the ground, and explain the next steps, from investigation to a written, itemised quote.
Send us photos of any cracks on WhatsApp to get started, or use our contact form.
