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.
- 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.
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.
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.
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.
