Concrete Foundation Repair
Crack injection, foundation sealing, pile and pile cap repair for commercial and industrial buildings — diagnosed properly, repaired to BS EN 1504, across London and the UK.
Concrete Foundation Repair Services
Concrete foundation repair covers the reinstatement of foundations, ground beams, pile caps and below-ground walls that have cracked, started passing water, or lost section through reinforcement corrosion. It is structural work, and the difference between a repair that lasts twenty years and one that fails again in two is almost always the diagnosis rather than the material.
MPS Concrete Solutions repairs and seals concrete foundations for commercial buildings, industrial units, car parks and residential blocks across the UK. As Sika-approved contractors with over 25 years of combined experience in structural concrete repair and waterproofing, we survey the foundation, establish why it has deteriorated, and specify a repair that addresses the mechanism — not just the visible damage.
The foundation problems we are most often called to:
- Cracked foundations and ground beams — cracks passing water into basements and plant rooms, or opening wide enough to threaten cover to reinforcement.
- Spalling and exposed reinforcement — carbonation or chloride-driven corrosion breaking out the concrete around the steel at foundation and plinth level. Our concrete spalling repair guide explains the mechanism and repair options in full.
- Leaking construction joints — the kicker joint at the base of a wall, or the joint between pile cap and ground beam, letting water through under hydrostatic pressure.
- Defective piles and pile caps — necking, voiding and honeycombing in the pile shaft, or water tracking up through the pile cap junction.
- Sulfate and chemical attack — degradation of the cement matrix in aggressive ground conditions, softening the concrete surface below ground.
- Foundations wet from the outside — below-ground walls with no effective waterproofing, wetting internal finishes and plant.
If a foundation crack is widening, stepped, or accompanied by distortion elsewhere in the building, get a structural engineer involved before any repair is specified. Movement has a cause, and sealing the crack without addressing it only hides the evidence.
Which Foundation Problem Do You Actually Have?
"Foundation repair" is used for three entirely different problems, and they are fixed by three different trades. Working out which one you are looking at is the whole job, because the wrong specialist will either quote for work you do not need or quote for nothing at all.
1. The ground is moving
Subsidence is the ground beneath the foundation sinking — usually clay shrinking in drought, tree roots drawing moisture out, a leaking drain washing fines away, or historic mining. Settlement is the structure bedding down into the ground under its own load, which happens to every building and only matters when it is uneven. Heave is the opposite: clay swelling as it takes water back, often after a tree is felled. Diagnosis needs a structural engineer, usually with trial pits, a drain survey and level monitoring over months. The remedy is underpinning, mini-piling or removing the cause — not concrete repair.
2. The concrete itself is failing
The foundation is still in the right place, but the concrete has lost section. Reinforcement corroding through carbonation or chloride attack expands and breaks the cover off; sulfate attack in aggressive ground softens the cement matrix; poor original compaction leaves honeycombing at pile caps and kickers. This is a durability failure, repaired to BS EN 1504 by breaking out, treating the steel and reinstating the section. This is the work we do.
3. It is letting water through
The foundation is structurally sound and in the right place, but water is tracking through a crack, a kicker joint, a pile cap junction or a service penetration into a basement, lift pit or plant room. Nothing needs underpinning and nothing needs breaking out — the water path is sealed, normally from the inside, under BS 8102:2022. This is also work we do, and it is the single most common reason we are called to a foundation.
To be straight about scope: MPS Concrete Solutions are concrete repair and structural waterproofing contractors. We do not underpin and we do not carry out ground stabilisation or resin soil injection. If your survey shows the ground is moving, you need a structural engineer and an underpinning contractor, and we will tell you so at the survey rather than sell you a repair that will crack again.
UK Foundation Types, and How Each One Fails
What can be repaired, and how it is accessed, depends on what you are standing on. UK foundations are designed to BS 8004 and Eurocode 7 (BS EN 1997-1), and the five types below cover almost all commercial and industrial stock.
| Foundation type | Where you find it | How it typically fails | What repair looks like |
|---|---|---|---|
| Strip / trench fill | Low-rise commercial, older industrial units, residential blocks | Differential settlement; sulfate attack in aggressive ground; cracking at changes of depth | Local breakout and reinstatement; crack injection; protective coating below ground |
| Pad foundations | Steel-framed warehouses and portal frames under each column | Corrosion at the holding-down bolt pocket; spalling at the plinth where the pad meets the column | Break out to sound concrete, treat the steel, reinstate with an R4 mortar to BS EN 1504-3 |
| Raft slab | Distribution centres, large-floor industrial, poor ground | Cracking at re-entrant corners; edge-beam spalling; water through shrinkage cracks into the slab | Resin injection of cracks; joint sealing; slab and joint-arris repair |
| Piled with ground beams | Multi-storey, city-centre and basement structures | Necking, voiding and honeycombing in the shaft; leakage at the pile-cap-to-beam joint | Pressure grout and resin injection to the shaft; joint injection rather than breakout |
| Basement box / retaining wall | Car parks, plant rooms, podiums, lift pits | Leakage at the kicker joint and construction joints; carbonation on the dry face | Hydrophilic waterstops, injection, tanking slurry or cavity drain to BS 8102:2022 |
On a piled foundation the single most useful thing to establish before anyone quotes is whether the water is coming through the shaft or through the pile cap construction joint — they look identical once the surrounding concrete is wet, and they are sealed by completely different methods. Our piling injection repair service covers that work in detail.
Reading a Foundation Crack
Crack width on its own does not prove anything, but it is the first measurement any engineer will ask for, and it is the quickest way to tell a cosmetic crack from one worth investigating. The classification below is the damage categories from BRE Digest 251, Assessment of damage in low-rise buildings, which is the reference UK loss adjusters and engineers work to.
| Category | Degree of damage | Approximate crack width | What it usually means |
|---|---|---|---|
| 0 | Negligible | Up to 0.1 mm | Hairline. Normal in concrete and render; no action. |
| 1 | Very slight | Up to 1 mm | Fine cracks, usually shrinkage or thermal. Matters for durability, not capacity. |
| 2 | Slight | Up to 5 mm | Visible, may admit water. Worth sealing; worth measuring again in three months. |
| 3 | Moderate | 5–15 mm | Investigate. Doors and windows sticking alongside this is a movement signal. |
| 4 | Severe | 15–25 mm | Structural engineer required before any repair is specified. |
| 5 | Very severe | Over 25 mm | Structural instability possible. Engineer and, often, temporary propping. |
The pattern matters more than the width
- Stepped or diagonal cracks that widen towards the top, tapering as they go down, usually point to ground movement rather than concrete deterioration.
- Cracks running parallel to and directly over a reinforcing bar, with rust staining, are corrosion cracks. The steel has expanded and split the cover.
- Horizontal cracking at a single level around the base of a wall is normally the kicker construction joint, not a crack at all.
- Map cracking or crazing with gel exudation suggests alkali-silica reaction, which is a materials problem and needs core sampling.
- Cracks that have been filled before and have reopened are still moving. Re-filling them rigidly will fail again.
Measure with a crack width gauge, mark and date each end of the crack, photograph it against a scale, and repeat monthly. Three readings over three months tell you more than any single survey, and it is free.
Diagnosis Comes First
Every foundation repair we carry out starts with establishing the mechanism. Concrete does not deteriorate for one reason, and the correct repair for carbonation-driven corrosion is quite different from the correct repair for sulfate attack or a live water path.
A typical foundation survey includes a visual and hammer survey to map delamination and drummy areas, cover meter readings to check the depth of concrete over the reinforcement, carbonation depth testing using phenolphthalein indicator on freshly broken faces, and where chloride contamination is suspected, sampling for analysis. Where water is coming through, we trace the path — a crack, a construction joint, a service penetration or the wall-to-slab junction all look similar once the surrounding area is wet, and they are sealed by different methods.
You get the findings in writing with photographs, a clear explanation of the cause, and an itemised specification and quotation for the repair. That documentation is usually what your insurer, structural engineer or managing agent needs to authorise the works.
Foundation Repair Methods
Most foundation defects are addressed by one of the following, or a combination of them.
Resin Injection of Cracks
Epoxy injection bonds dormant structural cracks and restores continuity. Polyurethane injection seals cracks that are actively leaking, reacting with the water to form a flexible seal that can be installed while the leak is live.
Reinforcement Treatment
Concrete broken out to sound material behind the steel, corrosion removed, reinforcement primed with a corrosion-inhibiting coating, and the section reinstated with polymer-modified repair mortar to BS EN 1504.
Pile & Pile Cap Repair
Pressure grout and resin injection to fill voids, necking and honeycombing in defective piles, and to seal water tracking through the pile shaft or the pile cap construction joint.
Foundation Sealing & Tanking
Crystalline and cementitious tanking slurries, injection hose systems and cavity drain membranes to seal below-ground foundations against water under BS 8102:2022 — applied internally where excavation is impractical.
Joint Sealing
Kicker joints, pile cap junctions and construction joints sealed with hydrophilic systems, fillet seals and resin injection — the leak paths that account for most below-ground water ingress.
Protective Coatings
Anti-carbonation and chemical-resistant coatings applied after repair to slow the ingress that caused the deterioration, extending the life of both the repair and the surrounding original concrete.
Choosing Between Them
| Symptom | Likely cause | Typical repair |
|---|---|---|
| Dry crack, stable width | Shrinkage or thermal, dormant | Epoxy resin injection |
| Crack passing water | Live water path under pressure | Polyurethane resin injection |
| Crack still moving | Ongoing movement — investigate first | Flexible joint sealing, not rigid injection |
| Rust staining and spalling | Reinforcement corrosion | Break out, treat steel, reinstate to EN 1504 |
| Damp patch at wall base | Kicker or construction joint leak | Joint injection and fillet seal |
| Water through pile cap | Pile cap construction joint | Grout and resin injection |
| Soft, eroded surface below ground | Sulfate or chemical attack | Cut out, reinstate with resistant mortar, coat |
Where the foundation is cracked and leaking rather than structurally deficient, the work is often far less disruptive than owners expect — most of it is carried out from the inside, without excavation, and the building can stay in use throughout.
Concrete Foundation Sealing & Waterproofing
A large proportion of foundation enquiries are not about structural capacity at all — the foundation is sound, but it is letting water into a basement, lift pit, plant room or undercroft. Concrete foundation sealing addresses that directly.
Where the outside face of the foundation is accessible, external tanking and drainage give the most robust result, intercepting water before it reaches the structure. In practice, excavating around an existing building is often impractical, prohibitively expensive, or ruled out by adjacent structures, services and access constraints. In those cases the foundation is sealed internally: cracks and joints injected with resin, the wall treated with a crystalline or cementitious tanking slurry that becomes part of the concrete, or a cavity drain membrane installed to manage water to a sump and discharge it.
All three are recognised approaches under BS 8102:2022, and the right one depends on the water pressure, the grade of internal environment you need, and whether the space is habitable, storage or plant. Our concrete waterproofing guide sets out how Type A, B and C systems compare, and basement tanking costs gives indicative pricing.
Below-Ground Foundation Work We Have Documented
Every job below has its own case study on this site, with what was found, what was specified and how long it took.
The Dumont, Albert Embankment, London
Internal cementitious render to a PUDLO waterproof-concrete attenuation tank for St James Group, working in confined space below ground. Turned around in three days.
Project George, Oxford Circus, London
Basement cavity drain installation for LDD Construction at 100–140 m² a day, finished in under five weeks against competitor quotes of eight or more.
Canary Wharf, London
Hydrophilic resin injection to stop active water ingress at the abutments of a bascule bridge, working beside the Jubilee Line exclusion zone.
Sterling Court, North London
Podium deck and soffit remediation over an occupied basement: breakout of defective concrete, re-levelling, and a waterproofing system installed above live areas.
Standards this work is carried out to
- BS EN 1504-3 — structural and non-structural repair mortars; class R4 where the repair carries load.
- BS EN 1504-5 — injection products for force-transmitting, ductile and swelling crack filling.
- BS EN 1504-7 — protection of reinforcement against corrosion.
- BS EN 1504-10 — site application, substrate preparation and quality control.
- BS EN 14630 — measuring carbonation depth by the phenolphthalein method.
- BS 8102:2022 — protection of below-ground structures against water ingress.
- BS 8004 and BS EN 1997-1 (Eurocode 7) — foundation and geotechnical design, which govern what the original foundation was meant to do.
MPS Concrete Solutions was founded in 2013 and works from Gamlingay, Cambridgeshire (SG19 3JW). We hold UKAS-accredited certification to ISO 9001, ISO 14001 and ISO 45001, are a Constructionline Gold member and SSIP accredited, a member of the Concrete Repair Association, and a Sika-specified applicator. Operatives hold NVQs in resin and grout injection, CSCS, SSSTS and SMSTS cards, PASMA and MEWP (3a/3b) training, and are confined-space trained.
Reviewed by Jerry Blears, Director (LinkedIn), MPS Concrete Solutions. Last reviewed October 2026.
How Long Foundation Repair Takes
Owners usually expect this work to be longer and more disruptive than it is. Indicative durations, assuming access is available and the cause has been established:
| Work | Typical duration | Disruption |
|---|---|---|
| Survey, carbonation and cover testing, written diagnosis | Half a day on site; report within a week | None |
| Resin injection of a single leaking crack or construction joint | One to two days | Works from inside; building stays in use |
| Localised breakout and reinstatement of a spalled pad or plinth | Two to five days per location, plus cure | Exclusion zone around the area only |
| Pile cap or pile shaft grout and resin injection | Three days to two weeks, by number of piles | Access to the cap needed; structure stays loaded |
| Internal tanking or cavity drain to a basement wall | 100–140 m² a day once set up | Area cleared progressively, in phases |
| Anti-carbonation or chemical-resistant coating after repair | One to three days plus overcoat intervals | Low; dependent on substrate moisture and dew point |
Cure and overcoat times, not labour, set most of these programmes. Repair mortars need their stated cure before a coating goes on, and coatings have a minimum substrate temperature and a maximum substrate moisture content — which is why winter work on an unheated below-ground structure takes longer than the same job in July.
Foundation Repair Contractors Across the UK
We work UK-wide from Cambridge, with teams most active across London and the South East. If you are searching for foundation repair near you, we cover commercial and industrial sites nationwide, including multi-site portfolios where a single contractor across all locations is simpler than appointing locally each time.
Our concrete repairs London service covers all Greater London boroughs, and we mobilise nationwide as concrete repair contractors for structural work outside the South East. Where foundation damage has made an area unsafe or water is actively entering a live plant room, we also provide emergency concrete repairs with rapid attendance.
Every enquiry starts with a free site survey. We will tell you honestly whether the problem is structural, whether it needs a structural engineer's involvement before we quote, and what the realistic repair options are — including doing nothing for now, where that is the sensible answer.
Frequently Asked Questions
How do you repair a cracked concrete foundation?
It depends on whether the crack is still moving and whether it is leaking. A dormant structural crack is normally repaired by epoxy resin injection, which bonds the two faces back together and restores structural continuity. A crack that is passing water is injected with polyurethane resin, which reacts with the water itself to form a flexible seal. A crack that is still moving is not injected rigidly at all — it is treated as a joint, sealed with a flexible system that accommodates the movement, once the cause of that movement has been established.
Can concrete foundations be waterproofed from the inside?
Yes. Where excavating around a building is impractical or prohibitively expensive, foundations and basement walls are sealed internally using Type B and Type C methods under BS 8102:2022 — resin injection of cracks and joints, crystalline and cementitious tanking slurries, injection hose systems and cavity drain membranes. Internal work avoids disturbing landscaping, access routes and neighbouring structures, and can usually proceed while the building stays in use.
What causes concrete foundation deterioration?
The most common cause is reinforcement corrosion driven by carbonation or chloride attack, which expands the steel and cracks the surrounding concrete. Below ground, sulfate attack from aggressive soils and groundwater degrades the cement matrix, and persistent water movement through cracks and construction joints leaches material and accelerates decay. Poor original compaction, honeycombing at pile caps and inadequate cover to reinforcement all shorten the time before these mechanisms take hold.
Do you repair concrete piles and pile caps?
Yes. Defective piles are reinstated using pressure grout and resin injection to fill voids, necking and honeycombing, and to seal water paths through the pile shaft or the pile cap junction. Exposed and corroding reinforcement is cleaned, treated and reinstated with polymer-modified repair mortars to BS EN 1504. Where a pile cap is leaking at the construction joint, the joint is injected rather than broken out. See our piling injection repair service for detail.
Is a cracked foundation always a structural problem?
No. Many cracks in concrete foundations are shrinkage or thermal cracks that formed early in the concrete's life and have been stable ever since. These matter for durability and water ingress rather than capacity. Cracks that are widening, stepped, or accompanied by distortion elsewhere in the structure need investigation by a structural engineer before any repair is specified, because sealing a symptom without diagnosing the cause simply hides it.
How much does concrete foundation repair cost?
It depends entirely on the mechanism and the extent. A localised crack injection or a single leaking construction joint is a modest, contained job; breaking out and reinstating spalled reinforced concrete is priced by area, typically from around £100–£200/m² for structural repair with reinforcement treatment; and below-ground foundation sealing is priced by the system and the access. Because foundation problems are so variable, we do not quote blind — every job starts with a free survey and a fixed, itemised quotation. Our concrete repair cost guide gives indicative UK ranges by repair type.
Is foundation repair the same as underpinning?
No, and conflating the two is the most common and most expensive mistake on this subject. Underpinning extends or replaces the foundation to reach better bearing ground, and it is the answer when the ground has moved — subsidence, heave or differential settlement. Concrete foundation repair reinstates concrete that has deteriorated while staying exactly where it was designed to be, and seals water paths through it. Underpinning a foundation whose only problem is a corroding bar is a six-figure solution to a four-figure defect; patch-repairing a foundation that is still sinking simply produces the same crack again next summer. We carry out the repair and sealing work and do not underpin — if the survey shows ground movement, you need a structural engineer and an underpinning or piling contractor, and we will say so.
How do I tell subsidence from a harmless shrinkage crack?
Three things separate them. Shape: movement cracks are typically diagonal or stepped and wider at the top than the bottom, while shrinkage and thermal cracks are more uniform in width along their length. Company: movement rarely arrives alone — doors and windows binding, floors falling away from skirtings, or cracking repeating on the opposite side of the building are movement signals. Behaviour: shrinkage cracks are dormant and do not change, whereas movement cracks open and close seasonally, widest in late summer on shrinkable clay. Mark and date each end of the crack, measure it with a crack width gauge monthly for three months, and classify it against the BRE Digest 251 categories. Anything in category 3 or above, or anything still moving, needs a structural engineer before a repair is specified.
How long does concrete foundation repair take?
Less time than most owners expect, because the majority of it is carried out from inside with the building in use. Injecting a single leaking crack or construction joint is a one- to two-day job. Breaking out and reinstating a spalled pad foundation or column plinth runs two to five days per location plus cure time. Pile cap and pile shaft injection is three days to two weeks depending on how many piles are involved. Internal tanking and cavity drain work progresses at roughly 100–140 m² a day once set up. Cure and overcoat intervals, not labour, usually set the programme — a repair mortar has to reach strength before a coating can go over it.
Will insurance cover foundation repair?
It depends which of the three problems you have. Subsidence, heave and landslip are insured perils under most UK commercial and residential buildings policies, so damage caused by ground movement is usually claimable and the insurer will appoint a loss adjuster and often their own engineer. Gradual deterioration is not: carbonation, chloride-driven reinforcement corrosion, sulfate attack and wear are excluded by almost every policy as wear and tear, as is a long-standing water leak. Escape of water that has physically damaged the structure sometimes is covered. Whichever route applies, a written diagnosis with photographs, test results and an itemised specification is what the adjuster or managing agent needs to authorise anything — which is what our survey report is written to provide.
Do you offer foundation repair near me?
We work UK-wide from our base near Cambridge, with teams most active across London and the South East, and we regularly travel further for commercial and industrial work and multi-site portfolios. If you are searching for foundation repair contractors near you, we cover the whole of the UK — and a single specialist across every site is usually simpler than appointing a different local contractor at each location. Send photographs and a location and we will tell you whether we can attend and what a survey involves.
Get Your Foundation Surveyed
Send us photographs and we will tell you what we think you are looking at. If it needs a site visit, the survey is free — and you get the findings, the cause and an itemised quotation in writing.
