For properties with prior subsidence history, Previous Subsidence Insurance may provide suitable protection.
What is settlement?
Settlement occurs in nearly all new buildings. As ground adjusts to structural weight and building materials dry and compact, properties shift marginally and settle into position.[2] This expected process usually stabilises soon after construction and seldom requires remedial action.
Settlement cracks serve as indicators: fine, tapering hairline fractures, frequently appearing around doors and windows, that cease widening once the building stabilises. These typically emerge shortly after construction or significant extensions, then discontinue.
What is subsidence?
Subsidence describes the downward movement of ground supporting a building, drawing foundations downward simultaneously.[1] Unlike settlement, subsidence can develop at any point during a building’s existence, sometimes decades post-construction, and typically signals an ongoing issue rather than isolated adjustment.
Several things can cause it, and often more than one is at play
- Trees and clay soil: The most prevalent UK cause.[2] Clay shrinks when dry and expands when wet; tree roots extract moisture from clay near foundations, particularly during dry summers. Larger, closer trees present greater risk.
- Leaking or collapsed drains: Leaks erode supporting soil or soften clay, undermining foundation support.[1]
- Decomposing material in the ground: Older properties built upon or near buried organic matter, such as tree stumps or vegetation, may subside as decomposition occurs and ground settles unevenly.
- Mining and made ground: Uncommon but significant for properties on former mining land or filled/built-up ground.[3]
Signs of subsidence
Subsidence cracks differ markedly from settlement cracks. They are typically thicker than a 10 pence coin, run diagonally, widen toward the top, and may appear around doors, windows, or where extensions meet original structures.[1] Unlike settlement cracks, these progressively expand rather than stabilising.
Upon noticing such cracks, particularly if appearing or worsening suddenly, or if doors and windows stick,[2] engage a chartered surveyor for assessment before drawing conclusions. Not every crack indicates subsidence; professional evaluation remains the sole reliable differentiation method.
What makes this happen?
Trees and clay form a problematic combination, particularly when clay exhibits high shrinkability and consequently expands when wet. Normally, deep underground moisture remains stable; however, trees extract subsoil water, causing clay shrinkage and foundation sinking.
Collapsing drains, culverts, and occasionally hidden mine shafts or bell mines can compromise ground supporting integrity. Buried organic material that decays or decomposes similarly destabilises partial or complete foundations.
Settlement vs subsidence: how to tell them apart
| Characteristic | Settlement | Subsidence |
|---|---|---|
| When it happens | Soon after construction, then it stabilises | Can happen at any point, often years later |
| Crack width | Fine, hairline | Usually thicker than a 10p coin |
| Crack shape | Vertical or tapering | Diagonal, wider at the top |
| Does it progress? | Stops once the building has settled | Tends to continue and can worsen |
| Cause | Normal adjustment of new materials and ground | Ground movement, often trees, clay or drainage |
| Needs repair? | Rarely | Usually, and can require underpinning |
Expert Perspective
Chris Konstantinou of Horner Blakey Insurance Brokers explains: “Settlement usually occurs in new or relatively new buildings. They are very heavy and cause the ground to compact, but this normally stops after a short while.”
Most buildings employ various materials with differing shrinkage rates.[2] Older, flexible construction buildings may display “summer cracks”, appearing in summer and closing in winter as materials absorb moisture, which prove completely harmless.
“Subsidence on the other hand is far more serious and occurs when the ground beneath the building is unable to support it. To rectify the problem, in most cases the property will be underpinned, which is a combination of steel and poured concrete underneath the property, to make the affected area stable.”
Can a house with a history of subsidence be insured?
Yes, though standard household insurers frequently prove challenging.[4] Mainstream providers often decline properties with subsidence histories, apply high excesses, or impose restrictive terms. This doesn’t render properties uninsurable; rather, specialist markets understanding risk management become necessary.
As an independent broker, Horner Blakey accesses insurers adopting considered perspectives on subsidence history, particularly where causes have been identified and remedial work, such as underpinning, has been completed and evidenced by surveyor’s reports. The firm collaborates to secure appropriate coverage levels, ensuring comprehensive risk assessment rather than automatic decline.
Get In Touch
Horner Blakey Insurance Brokers provides quotations for properties experiencing subsidence and settlement. Required documentation includes surveyor’s reports, which insurers typically mandate for quotation provision. Surveys commonly reveal previous property issues discovered during purchase processes.
For complimentary insurance review and additional information, contact Horner Blakey Insurance Brokers at 020 7929 0108.
