What is it?
Subsidence is the downward movement of the ground beneath a building's foundations, causing the structure to sink unevenly. It differs from settlement (which is usually harmless and self-limiting) and heave (upward movement caused by clay absorbing moisture). Subsidence is progressive — meaning it can get worse over time if the underlying cause is not addressed. The most common trigger in the Midlands is clay soil shrinkage caused by tree roots extracting moisture from the ground.
Signs of Subsidence to Look For
- Diagonal or staircase cracks wider than 1mm, typically at the corners of windows and doors
- Cracks that are wider at the top than the bottom
- Doors and windows sticking as the structure distorts
- Rippling or crinkling wallpaper, especially at wall-ceiling junctions
- Gaps appearing at skirting boards or where walls meet door frames
- Uneven or sloping floors in severe cases
When to Worry
Not all cracks mean subsidence. Hairline cracks less than 1mm wide are common in most properties and are usually caused by normal thermal movement or plaster shrinkage. You should worry if cracks are wider than 1mm, follow a diagonal stepped pattern through brickwork, are getting worse over time, or are accompanied by sticking doors and uneven floors. If in doubt, a structural engineer can tell you definitively whether movement is active.
Common Causes of Subsidence
- Tree roots extracting moisture from clay soils — responsible for around 70% of UK subsidence cases
- Clay shrink-swell movement during prolonged dry weather, particularly common across the Midlands
- Leaking drains washing away or softening the soil supporting foundations
- Historic mining activity in Nottinghamshire, Derbyshire and north Leicestershire
- Made-up ground or poorly compacted fill beneath older properties
Frequently Asked Questions
What are the first signs of subsidence?
The earliest signs are usually fine diagonal cracks appearing at the corners of windows and doors, particularly on the outside of the building. You may also notice doors or windows becoming difficult to open or close, or wallpaper crinkling at wall-ceiling junctions. These signs often appear after a prolonged dry spell when clay soils shrink.
How do I tell the difference between subsidence and settlement?
Settlement is the natural process of a building bedding into the ground, usually occurring within the first few years after construction. Settlement cracks are typically fine, symmetrical and stable. Subsidence cracks tend to be wider than 1mm, diagonal, wider at one end, and may worsen over time. Only a structural engineer can confirm the diagnosis through inspection and crack analysis.
Do I need a structural engineer or a surveyor?
A RICS surveyor provides a general property condition report, while a structural engineer provides specialist diagnosis of structural problems. For suspected subsidence, you need a structural engineer who can analyse crack patterns, assess foundation movement and provide the technical report that insurers and lenders require. Our work is supervised and checked by a Chartered Engineer (CEng MICE).
Will my insurance cover subsidence investigation?
Most buildings insurance policies cover subsidence investigation and repair, subject to a standard excess of £1,000. However, policies vary, so check your cover before making a claim. An unnecessary claim can affect your future premiums. Our independent report can be submitted alongside your claim to support the investigation.
How long does a subsidence inspection take?
The site visit itself typically takes 1 to 2 hours, depending on the size of the property and the extent of the cracking. Your written report is then delivered electronically within 3 to 7 working days. If monitoring is recommended, we revisit after an agreed period to check whether movement is ongoing.
Can subsidence be fixed without underpinning?
Yes, in many cases. If tree roots are the cause, managing or removing the tree may be sufficient. Leaking drains can be repaired. Resin injection is a modern alternative to traditional underpinning that is less disruptive and often less expensive. The correct remedy depends entirely on the diagnosis, which is why a proper investigation is the essential first step.