Repair options
Subsidence repair in Hampshire: ways to fix foundations
Find out what each repair method involves and when a specialist might recommend it. Read through the options below to understand how sinking foundations, cracked concrete and unstable ground are dealt with across Hampshire.
What a subsidence survey covers first
A crack in a wall does not always mean the ground beneath your home is moving. Seasonal changes, leaking pipes and simple settling all leave marks that look alarming but behave differently.
A subsidence survey establishes whether the movement is active or historical, and what is driving it. The specialist examines the pattern of cracking, checks door and window frames for distortion, and looks at the soil type around the foundations. Drainage runs and nearby trees matter too, because roots and water both change how the ground supports a building.
Once the cause is identified, the survey report sets out what needs to happen next. Sometimes monitoring over several months is enough. Other times a repair method must be chosen straight away. Understanding this first step helps you make sense of every option that follows on this page.
Underpinning to deepen existing foundations
When the soil under a home cannot support the weight above it, underpinning extends the foundations down to a stable layer. This is heavy work, usually involving excavating sections of ground beneath the walls and pouring new concrete in controlled stages.
The specialist digs bays one at a time so the rest of the building stays supported while each section cures. Once the new concrete has set, the next bay is opened. This sequence continues until the entire affected wall sits on deeper footings.
Underpinning suits situations where the original foundations were built too shallow, or where the ground has permanently lost its bearing capacity. It is disruptive by nature, because soil has to come out from under the house. But for severe or ongoing movement, deepening the foundations remains the most reliable way to stop it. A structural engineer will specify the depth and the sequence before any digging begins.
Resin injection as a less disruptive option
Not every case of subsidence requires excavation. Resin injection stabilises the ground without removing large volumes of soil. A specialist drills small holes through the floor slab or alongside the foundation and pumps a two-part expanding resin into the voids below.
As the resin expands, it compacts loose soil and fills gaps left by erosion or shrinkage. In some cases the expansion generates enough force to lift a sunken floor back towards its original level. The process is measured constantly during injection, so the technician controls exactly how much material goes in and how far the ground rises.
This method works well where the problem is localised, such as a single corner of a room dropping, or where access for heavy machinery is restricted. Because the holes are small and no trenches are dug, disruption inside the home is minimal. The resin cures quickly once injected, leaving the ground stable soon after the work finishes.
Repairing cracked concrete floors and slabs
Concrete floors crack for many reasons. A driveway might split because frost got into the sub-base. A garage floor might sink if the fill underneath was never compacted properly. Inside a home, a cracked slab often points to moisture changes in the soil beneath it.
A specialist dealing with concrete cracking will assess whether the slab can be repaired or needs replacing. Small cracks are cleaned and filled with a flexible compound that moves with temperature changes. Larger fractures, or slabs that have dropped significantly, may require lifting with resin or breaking out and recasting.
The approach depends on what the concrete sits on and what it supports. A patio slab resting on sand behaves differently from a structural floor tied into the walls of your home. Getting the right repair means identifying why the concrete failed in the first place, rather than just filling the visible gap.
Screw piling for weak or filled ground
Some parts of Hampshire are built on made ground, where old quarries, ponds or rubbish tips were filled in before houses went up. Standard foundations struggle on this type of soil because it compresses unpredictably.
Screw piling drives steel shafts with helical plates deep into the ground, past the weak fill and into firm strata below. The piles act like long screws anchoring the structure to something solid. They can be installed quickly, generate almost no spoil, and do not need wet concrete to cure.
A specialist uses screw piles when extending a home onto soft land, or when an existing foundation is failing because the ground beneath it was never suitable. The equipment is compact enough to work in tight gardens and beside boundary walls. Because the installation creates very little vibration, it is often chosen near older buildings where shaking could worsen existing cracks.
Specialist repairs for cob, flint and chalk walls
Older Hampshire homes were often built from materials found nearby: flint nodules, chalk blocks, cob made from local clay and straw, bound together with lime mortar. These walls move and breathe differently from modern brickwork.
Standard cement-based repairs trap moisture inside cob and chalk, accelerating decay. A specialist working on these structures uses lime-based mortars and techniques suited to the original construction. Cracks in cob walls are stitched back together using natural materials that flex with seasonal humidity changes rather than resisting them.
If subsidence affects a period property, the repair method must respect the wall fabric. Underpinning a flint wall requires particular care because the stones rely on their mortar matrix for strength. Disturbing that matrix without understanding how the wall transfers loads can cause more damage than the original movement. Specialists experienced with historic buildings plan each stage around the specific materials they find.
Garages, porches and garden walls
Small structures suffer from ground movement just as houses do, but they are built to lighter standards. A garage often sits on a shallow strip footing or a simple concrete pad. Porches are frequently added later, with foundations that do not tie properly into the main house.
Garden walls have no roof load holding them down, so wind pressure and root growth push them over easily once the base shifts. Cracking in these structures is common, and owners often worry it signals a wider problem with the main building.
A specialist assesses outbuildings separately from the house. Sometimes a leaning garage wall simply needs rebuilding on a better base. Other times the cracking reveals that the whole plot is on unstable ground. Repair options range from stitching masonry and adding ties, to installing small piles beneath a porch footing. The scale of the work matches the scale of the structure.
Made ground and soft coastal soils
Homes near the Hampshire coast, around Portsmouth Harbour, the Solent or the edges of Southampton Water, often sit on ground that was reclaimed from marshland or infilled after industrial use. This soil is soft, compressible and prone to shifting when water tables change.
Subsidence on made ground rarely stops on its own. The fill material continues to consolidate under the weight of the building, sometimes decades after construction. Coastal properties also face salt erosion in masonry and fluctuating groundwater levels that wash fine particles away from beneath foundations.
Specialists working in these areas choose methods that account for ongoing settlement. Screw piling reaches past the fill entirely. Resin injection densifies the loose layers directly beneath the slab. The right choice depends on how deep the soft material goes and whether the movement is uniform or tilting one side of the home. Local knowledge of the geology matters here, because conditions change street by street along the coast.
Tell us what you have noticed at home
Send details of the cracking or movement you have seen. A specialist firm will review what you describe and advise on the next step. There is no obligation to proceed with any work.
- No commitment required
- Specialist reviews your details
- Local firms cover Hampshire
Repairs
- Subsidence survey
A subsidence survey looks at cracks, levels and ground conditions before a cause is named. See what a specialist checks, measures and rules out.
- Underpinning
Underpinning in Hampshire suits houses with shallow or unevenly supported foundations. Read what the work involves, the stages and the disruption.
- Resin injection
Resin injection beneath foundations uses geopolymer resin under footings and slabs to firm up weak ground, a less disruptive option than piling.
- Concrete cracking
Cracked concrete floor repair covers garage slabs, drives, patios and solid floors. Learn what causes the cracking and which repair options suit each case.
- Screw piling
Screw piling in Hampshire suits homes on soft or filled ground. See how screw piles are wound in, load tested and tied into the structure above.