Guides
Guides to cracks, subsidence and structural repairs
Plain-English guides written to help you understand what is happening to your building and what the options cost.
How serious is this crack?
A crack is usually serious when it is wider than about 5 mm, keeps growing, tapers, or shows on both sides of the same wall. Most hairline cracks are cosmetic, but width, direction and change over time tell you whether one needs an expert look.
Read the guideSigns of subsidence and what to do first
Subsidence is the downward movement of the ground beneath a building’s foundations, and its typical signs are new diagonal cracks near doors and windows, sticking doors and cracks that widen after dry weather. The first steps are to photograph and measure the cracks, check for leaking drains, tell your insurer, and leave nearby trees alone until you have advice.
Read the guideSubsidence insurance claims explained
A subsidence insurance claim is a claim on your buildings policy for damage caused by the ground moving beneath your foundations, and it usually runs in stages: report, investigate, deal with the cause, monitor, then repair. Claims often take many months, and the subsidence excess is commonly about £1,000.
Read the guideUnderpinning vs resin injection
Underpinning strengthens a building’s foundations by taking them down to firmer ground, while resin injection stabilises the existing ground by injecting an expanding resin beneath the foundations. Which fits depends on the soil, the depth of firm ground, access and the engineer’s diagnosis, and many subsidence problems need neither.
Read the guideCrack stitching explained
Crack stitching is a masonry repair in which stainless steel helical bars are bonded into slots cut across a crack, tying the cracked brickwork back together so it acts as one wall again. It works well once the cause of the crack has stopped, but it is not a fix for ongoing movement, failed wall ties or a failing lintel.
Read the guideWall tie failure
Wall tie failure is when the metal ties linking the two leaves of a cavity wall corrode and stop holding them together, letting the outer leaf crack, bulge or lose stability. The usual sign is horizontal cracking in the mortar every few courses, and the fix is a survey followed by new remedial ties, with old ties isolated or removed where needed.
Read the guideBowing and bulging walls
A bowing wall is one that has bent or bulged out of line, usually because it is no longer properly tied to the floors, the roof or its other leaf. Most can be stabilised where they stand with lateral restraint ties or straps, but a wall that has moved too far may need part of it rebuilt.
Read the guideBuying a house with subsidence
Buying a house with subsidence means buying one where the ground beneath has moved, either in the past and been repaired, or now. It can be a sound purchase with the right survey, paperwork and insurance, but this guide is general information, not legal or financial advice, so speak to a surveyor, a solicitor and a mortgage broker before you commit.
Read the guideTrees and subsidence
Trees cause subsidence when their roots draw water from shrinkable clay beneath a building, making the clay shrink and the foundations drop, usually worst in late summer. Felling a tree is not a simple fix, because the clay can swell back and cause heave, so get advice before cutting anything.
Read the guideClay soil subsidence in the UK
Clay soil subsidence happens when shrinkable clay beneath a building dries out, shrinks and lets the foundations drop, and it is the most common cause of subsidence in the UK. It is most frequent on the high-plasticity clays of London and the South East, but shrinkable clays occur across much of England and parts of Wales.
Read the guideMining subsidence claims
A mining subsidence claim is a request for repairs or compensation when old or current mine workings have caused the ground under a property to move. For coal mining, claims go to the Mining Remediation Authority, formerly the Coal Authority, or the responsible mine operator, and you should tell your home insurer as well.
Read the guideThe Party Wall Act and structural repairs
The Party Wall Act is a 1996 law in England and Wales that sets out how you must notify your neighbour before certain work to a shared wall or excavations close to their building. It often applies to structural repairs such as underpinning a party wall, but not to minor work, and there is no equivalent Act in Scotland or Northern Ireland.
Read the guideStructural repair costs in 2026
Structural repair costs in 2026 range from about £80 per metre for crack stitching to £3,500 per metre of wall for mini-piled underpinning, with most single repairs falling between a few hundred pounds and a few thousand. All figures here are guide prices including VAT; they vary by region and access and are confirmed in writing after a survey.
Read the guideLintel failure: signs and replacement
A lintel is the beam that carries the wall over a window or door opening, and lintel failure is when it rots, cracks, corrodes or sags so it no longer supports the masonry above properly. The usual signs are cracks running up from the corners of the opening, sagging brickwork and windows or doors that stick, and the fix is usually a replacement lintel.
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