Typical warning signs include:

• Diagonal cracks (often wider at the top than bottom)
• Cracks wider than ~3mm
• Doors or windows sticking or misaligning
• Sloping or uneven floors
• Gaps between walls and ceilings.

Hairline cracks alone don’t necessarily mean subsidence.

How subsidence is investigated

• Structural survey by a qualified surveyor or engineer
• Monitoring cracks over time
• CCTV drain surveys
• Soil testing (especially for clay content)
• Tree/root analysis

This process can take months to confirm ongoing movement.

How subsidence is fixed

Solutions depend on the cause:

• Repairing or replacing drains
• Managing or removing trees
• Improving drainage
• Underpinning (strengthening foundations)
• Resin or grout injection (in some cases)

Many cases are resolved without underpinning.

Insurance and property value

• Subsidence is usually covered by buildings insurance
• Claims can take time but are common and manageable
• Once properly repaired, many properties remain stable long-term
• Past subsidence must be disclosed when selling

Subsidence Caused By Vegetation

How vegetation causes subsidence

• Tree roots absorb significant amounts of water
• Clay soils shrink as moisture content drops
• Foundations lose support and move downward
• Movement is usually uneven (differential), leading to cracking



Roots rarely damage foundations directly — the issue is soil desiccation, not physical root pressure.

Highest-risk conditions

• Shrinkable clay soils
• Shallow foundations (common in older properties)
• Large or mature trees close to the building
• South- or west-facing elevations (greater drying)
• Extended dry periods

Common vegetation involved

• Trees: oak, willow, poplar, elm, plane
• Large shrubs and hedges: leylandii, laurel

Risk increases when vegetation is within its mature height distance of the building.

Typical signs

• Diagonal cracks, often tapering
• Cracks opening during summer and closing in winter
• Localised damage on the elevation nearest vegetation
• Sticking doors or windows

Management and repair

• Pruning or phased reduction of trees
• Root barriers in some cases
• Controlled or staged tree removal (to avoid heave)
• Monitoring before structural repairs
• Most vegetation-related subsidence cases are resolved without underpinning



Subsidence Caused by Damaged Drains & Pipes

How it happens

• Leaks from pipes or drains release water into the soil
• Fine particles are washed away, creating voids
• Ground strength and bearing capacity are reduced
• Foundations move unevenly, causing structural cracking

Unlike vegetation-related subsidence, drain-related movement can develop quickly if the leak is significant.

Common Signs

• Cracks appearing suddenly or worsening rapidly
• Damage concentrated near kitchens, bathrooms, or drainage runs
• Persistent damp patches or unexplained water usage
• Soft or sunken ground outside the property
• Drainage issues or foul odours

Investigation

Confirmation usually involves:

• CCTV drain surveys
• Pressure testing of water pipes
• Structural assessment of cracking
• Localised ground investigation if voids are suspected

Drain-related subsidence is often easier to diagnose than other forms because the source of movement can be clearly identified.

Repair & Resolution

• Repairing or replacing damaged drains or pipes
• Reinstating or stabilising affected ground
• Monitoring to confirm movement has stopped
• Carrying out structural repairs once stability is proven

In many cases, underpinning is not required if the problem is addressed early.

Subsidence caused by Landslides

How it happens

• Soil or rock loses strength, often due to excess water
• A slip surface develops within the slope
• Ground moves downhill under its own weight
• Foundations move with the ground mass, causing distortion

Movement may be sudden after heavy rainfall, or slow and progressive over time.

Common Causes

• Prolonged or intense rainfall
• Poor or blocked drainage
• Weak soil layers within a slope
• Made ground or poorly compacted fill
• Excavations or added loads near slope edges
• Failure of retaining walls or slope support structures

Typical Signs

• Cracking across multiple elevations of a building
• Diagonal or stepped cracks that continue through walls and floors
• Leaning walls, chimneys, or retaining walls
• Sloping floors or noticeable building tilt
• Ground cracks, bulging, or depressions outside the property

Damage is often widespread, not confined to one small area.

Investigation

Diagnosis usually requires specialist input and may include:

• Structural and geotechnical surveys
• Boreholes and soil testing
• Slope movement monitoring
• Drainage assessments
• Review of historical ground movement or weather events

A geotechnical engineer is typically required to confirm landslide-related subsidence.

Repair & Resolution

• Improving surface and underground drainage
• Reducing loads on the slope
• Constructing or strengthening retaining walls
• Installing ground anchors or soil nails
• Piled or reinforced foundation solutions

Landslide-related subsidence is often more complex than other types but can be successfully managed with appropriate engineering solutions.