Retaining wall repair means stabilising, strengthening or rebuilding a wall that holds back soil, usually after it has started to lean, bulge or crack. The usual culprits are water pressure behind the wall, a foundation too small for the load, roots, extra weight at the top, or a wall that was only ever built as a garden wall. A chartered structural engineer decides whether it can be repaired or must be rebuilt and designs the work. We carry out that design. If a wall looks close to failing, keep people away from it and get advice promptly.
Where do we see retaining walls around Merseyside?
Retaining walls turn up wherever a house or garden has been built into a slope. On the Wirral they are familiar on sloping plots towards the Dee around Heswall, where gardens often step down in terraces. Older sandstone walls bound gardens and lanes in places like Woolton. Elsewhere they hold up driveways cut into front gardens, support raised patios, line steps to front doors, and separate houses on rising streets from the pavement below.
Many were built decades ago, some without any engineering at all. A wall that has stood for a century can still fail when something changes: a new driveway at the top, a blocked drain behind it, a tree growing nearby or simply years of wet winters.
Why do retaining walls fail?
| Cause | What tends to happen |
|---|---|
| Water building up behind the wall | Blocked or missing weep holes and no drainage behind the wall let water pressure build after rain, pushing the wall outwards |
| Foundation too small or too shallow | The wall rotates forwards or slides at the base, often showing as a lean from the bottom up |
| Extra load at the top | A driveway, parked cars, new patio, shed or raised beds add pressure the wall was never designed for |
| Tree roots | Roots growing behind or under the wall can push it out or disturb its footing |
| Weathering and frost | Eroded mortar, spalled bricks or decaying stone weaken the wall until it bulges or loses sections |
| Never designed to retain | A thin garden or boundary wall that has had soil built up behind it over the years |
What are the warning signs?
- LeaningThe wall is visibly out of plumb, or the lean has increased since you first noticed it.
- BulgingA belly in the face of the wall, often part-way up, where soil and water pressure are greatest.
- CrackingStepped, horizontal or vertical cracks, especially if they are widening.
- Loose or missing masonryBricks or stones falling out, or mortar washing away.
- Wet face or seepageWater staining or running from the wall after rain, or the ground at the top staying waterlogged.
- Movement at the topCracks in a driveway, path or patio above, or ground dropping just behind the wall.
A failing retaining wall can collapse suddenly. Keep people and pets away from the base and the top, do not park cars or stack materials near it, and do not dig at the base or remove soil from behind it to "take the pressure off". If it could fall onto a footpath, road or neighbouring property, get urgent professional advice; the council's building control team can be contacted about dangerous structures.
How is a retaining wall repaired?
- Find out what you have. We ask how high the wall is, what it retains, what sits above it, whether it is getting worse and whether it is on a boundary. We visit to look.
- Engineer's assessment. A chartered structural engineer inspects the wall and decides whether investigation is needed, for example a trial hole at the base to see the foundation, or a look at the ground and drainage behind. See soil and site investigation.
- Make it safe. Where needed, the area is cordoned off and the engineer specifies any temporary support.
- Design the repair. The engineer chooses the approach and specifies the details.
- Carry out the work. We do the work to the design, in stages where the wall cannot be left unsupported, with Building Control involved where the work falls under the Building Regulations.
Depending on what the engineer finds, the repair might be one or more of these: clearing or forming drainage behind and through the wall; repointing and replacing damaged masonry; adding ties, anchors or buttresses; deepening or widening the foundation; or taking the wall down and rebuilding it as a properly designed retaining structure with drainage built in. Where the wall forms part of the house itself, for example a front wall to a lower ground floor, the work overlaps with bowing wall repair and sometimes underpinning.
Does water have to be dealt with too?
Almost always. Water is the single most common reason retaining walls move. That might mean clearing weep holes, laying new drainage behind a rebuilt wall, or fixing a leaking drain or downpipe that has been soaking the ground. Our page on drainage-related subsidence explains how drains are surveyed.
Insurance, boundaries and neighbours
The ABI says buildings insurance usually covers garden walls for subsidence only if they are damaged at the same time as the house, and other causes may be treated differently. If your house is cracking too, contact your insurer before arranging any work. If the wall is on or near a boundary, ownership and responsibility can be complicated; your deeds or a solicitor can help, and some work may involve the Party Wall etc. Act 1996. We do not give legal advice. Where tree roots are involved, check with your council before any tree work, as protected trees and conservation areas have their own rules.
What affects the cost?
The height and length of the wall, how much soil it retains, access for plant and materials, whether it can be repaired or must be rebuilt, the drainage needed, temporary support, disposal of spoil and any finishes such as matching stone. We price once the engineer has designed the scheme. Retaining walls sit alongside our underpinning and structural repairs in Liverpool, because the same engineering principles of load, ground and water apply.
Wall leaning or bulging?
Call 07777 659786 or use the form. Tell us roughly how high the wall is, what is above it and whether it has moved recently, and we will call you back about getting it assessed as part of our structural repair service across Merseyside.
Frequently asked questions
Why is my retaining wall leaning?
Common causes include water building up behind the wall because drainage holes are blocked or missing, a foundation too shallow or narrow for the load, tree roots, extra load at the top such as a driveway or new patio, frost damage to the masonry, or a wall that was never designed to retain soil. Often several act together. A structural engineer needs to inspect to say which apply.
Is a leaning retaining wall dangerous?
It can be. A retaining wall that is leaning, bulging, cracking or shedding bricks may fail without much warning, particularly after heavy rain. Keep people, especially children, away from the base and the top of the wall, avoid putting extra load near it, and get professional advice promptly. If it could fall onto a path or road, the council's building control team can be contacted about dangerous structures.
Can a retaining wall be repaired, or does it need rebuilding?
It depends on the cause and how far the wall has moved. Some walls can be stabilised with improved drainage, repairs to the masonry, ties or anchors, or added buttresses. Others have moved too far or were never designed to retain soil and need taking down and rebuilding to an engineer's design. The engineer decides after inspection and, where needed, investigation of the ground.
Does home insurance cover a collapsed retaining wall?
The ABI says buildings insurance usually covers garden walls, fences, gates, patios and drives for subsidence only if they are damaged at the same time as the house. Other causes may be treated differently, and policies vary. Check your wording or contact your insurer before arranging work, especially if the house is cracking as well.
Who is responsible for a retaining wall on a boundary?
It depends on who owns the wall and the land, which your title deeds or a solicitor can help establish. Where a wall sits on or near a boundary, the Party Wall etc. Act 1996 may also apply to some work. We do not give legal advice, so it is worth clarifying ownership and talking to your neighbour before any work is planned.