Buying a Property Near Mature Trees: Should Cracking and Subsidence Concern You?
Buying a Property Near Mature Trees: Should Cracking and Subsidence Concern You?
Mature trees can make a residential street or garden considerably more attractive. They provide shade, privacy, wildlife habitat and a sense of established character. Their presence does not mean that a property is suffering from subsidence. Equally, trees should not be dismissed where cracking, distorted openings or a history of structural movement exists. The correct assessment depends upon the building, foundations, soil, tree species, distance, drainage and pattern of movement. No single factor provides the answer by itself.
What Is Subsidence?
Subsidence describes downward movement of the ground supporting a building. This can cause foundations and the structure above to move. It differs from settlement, which commonly occurs as a new building or extension adjusts to the ground after construction. It also differs from heave, where the ground moves upwards.
Cracking can develop for many reasons unrelated to subsidence, including:
· Thermal movement
· Drying shrinkage
· Differential movement between old and new construction
· Corrosion of embedded metalwork
· Inadequate support above openings
· Roof spread
· Drainage leakage
· Deterioration of materials
· Historic settlement
The existence of a crack should begin an assessment, not conclude it.
Why Can Trees Affect Buildings?
Trees absorb water from the ground through their roots. On shrinkable clay soil, a reduction in moisture can cause the ground to decrease in volume. If foundations are sufficiently shallow and the change occurs unevenly, part of a building may move more than another. This can produce distortion and cracking. The level of risk is influenced by:
· Soil type
· Tree species
· Height and maturity
· Distance from the building
· Root distribution
· Foundation depth
· Seasonal weather
· Nearby drainage
· Previous tree management
· The building’s construction and alteration history
A large tree close to a house on clay soil deserves consideration, but it does not prove that movement has occurred.
Not Every Part of London Has the Same Soil
Ground conditions vary considerably across London and the surrounding areas. Some locations contain highly shrinkable clay, while others have gravel, sand, made ground or mixed deposits. Local geology affects how soil responds to moisture changes. General geological information can provide useful context but does not establish the conditions beneath one property. Urban sites can contain disturbed or filled ground, and foundation depths are usually concealed. Where serious movement is suspected, site-specific investigation may be required. This could include trial pits, soil testing and arboricultural information under the direction of a structural engineer or other suitable specialist.
What Does Tree-Related Cracking Look Like?
There is no crack shape that confirms tree-related subsidence on its own. Potentially significant movement can produce diagonal or stepped cracking, often around windows, doors and weaker sections of masonry. Cracks may be wider at one end and affect both internal and external surfaces. The surveyor should consider:
· Direction and continuity
· Whether masonry or only plaster is affected
· Relationship with openings
· Distribution across the building
· Distortion of frames and floors
· Evidence of previous repair
· Whether cracks pass through recent decoration
· Proximity to trees and drainage
· Differences between the original house and extensions
Seasonal opening and closing can be relevant, but a single inspection provides only a snapshot. Fine cracks within new plaster may result from drying or thermal movement. Conversely, a narrow crack can still be important if it forms part of a wider pattern of distortion.
Extensions Can Behave Differently
An extension may have deeper or shallower foundations than the original building. The two structures can therefore respond differently to changes in the ground. Cracking commonly develops at the junction between old and new construction. This can result from historic differential movement, inadequate bonding, thermal effects or foundation movement. The presence of a tree near that junction may be relevant, but causation should not be attributed without examining the complete evidence. Structural drawings, foundation details and Building Regulations records can help establish how the extension was constructed.
Drainage Should Not Be Overlooked
Defective drainage is an important potential cause of ground movement, particularly around older buildings.
Cracked pipes, leaking joints and damaged gullies can soften, wash away or alter the moisture content of supporting ground. Tree roots may enter an existing defect and contribute to a blockage, but sound drains are not normally damaged simply because roots are nearby.
The survey should consider:
· The position of inspection chambers
· Drainage routes relative to cracking
· Broken or displaced gullies
· Signs of blockage or leakage
· Previous drainage repairs
· Movement close to bathrooms, kitchens and rear additions
A closed-circuit television drainage survey and appropriate testing may be required where leakage is suspected.
Removing or pruning a tree will not resolve movement caused principally by defective drainage.
What Do Previous Repairs Reveal?
Cracks are often filled and redecorated before a property is marketed. Previous repair does not necessarily indicate concealment; minor cracking is routinely repaired during maintenance. However, repeated repairs can make the history difficult to understand. The purchaser should request:
· Earlier survey reports
· Structural engineer’s reports
· Monitoring records
· Insurance correspondence
· Repair specifications
· Drainage reports
· Photographs taken before redecoration
· Arboricultural reports
· Details of previous tree work
If cracks have reopened after repair, the cause and timing should be investigated before they are treated cosmetically again.
Has the Movement Stopped?
One inspection does not always establish whether movement is active, seasonal or historic. Fresh fractures, clean crack surfaces, displaced masonry and cracking through recent decoration can indicate more recent movement. Longstanding repairs that remain intact may support a conclusion that movement is stable.
Where evidence remains uncertain, crack monitoring may be appropriate. Monitoring should have a defined method, duration and purpose. It should record more than occasional photographs without measurements or fixed reference points. Severe cracking or significant distortion may require immediate structural investigation rather than waiting for a monitoring period.
Should the Tree Be Removed?
Tree removal should not be recommended automatically. Unnecessary removal can damage local amenity, breach legal protections and, in some soil conditions, contribute to ground recovery or heave. A tree may also be protected by a Tree Preservation Order or stand within a conservation area.
The decision should consider:
· Whether the tree is contributing to movement
· Species and water demand
· Size, condition and distance
· Soil and foundation information
· Evidence of active movement
· Alternative management options
· Planning protection
· The risk of heave
· Ownership of the tree
An arboriculturalist should advise on tree condition and management. A structural engineer should address foundation movement. Their evidence may need to be considered together. Removing a neighbour’s tree is not an option available to a purchaser without the owner’s agreement and any necessary consent.
What If a Tree Was Removed Previously?
The absence of a tree at the time of inspection does not mean that it has no relevance. A large tree may have been removed before marketing, leaving a stump or an area of recent landscaping. On shrinkable clay, soil can regain moisture after removal and increase in volume.
This does not mean that heave will necessarily occur. Risk depends upon the history of the tree, soil, foundations and duration of moisture depletion. The purchaser should ask when the tree was removed, why and whether professional advice was obtained. Historic aerial photographs and previous sales information can sometimes assist.
Trees Belonging to Neighbours or the Council
A tree does not have to stand within the property boundary to be relevant. Trees in neighbouring gardens, streets and communal land can be closer to the building than trees owned by the purchaser. Responsibility for management will rest with the relevant owner. The survey should record significant nearby trees where visible, but it is not a complete arboricultural inventory. Species identification and condition assessment may require specialist advice. The purchaser should also establish whether access or consent could be obtained if future investigation or management became necessary.
Insurance and Previous Subsidence Claims
A previous subsidence claim can affect insurance, mortgage lending and future resale.
The purchaser’s solicitor should ask specifically about:
· Historic claims
· Structural repairs
· Underpinning
· Monitoring
· Continuing insurance arrangements
· Policy excesses
· Exclusions or special terms
· Guarantees for remedial works
An insurer’s decision to close a claim does not replace an independent assessment of the property’s present condition. The purchaser should obtain suitable insurance terms before exchange if movement or a previous claim is disclosed.
Does Cracking Mean the Property Should Be Rejected?
Cracking should be assessed proportionately. Many properties contain historic or minor cracks that do not indicate continuing structural failure. The purpose of a survey is not to label every crack as subsidence. It is to explain what was observed, how it relates to the construction and which further investigations are justified.
Depending upon the evidence, recommendations may include:
· Reviewing previous records
· Structural engineer’s assessment
· Drainage survey
· Crack monitoring
· Trial pits and soil investigation
· Arboricultural advice
· Insurance enquiries
· Localised repair after the cause is established
The investigation should narrow uncertainty rather than simply produce a long list of generic possibilities.
Should You Buy a Property Near Mature Trees?
Mature trees are not inherently incompatible with buildings. Many properties have stood near substantial trees for decades without significant movement. Risk increases where shrinkable soil, shallow foundations, high-water-demand trees, defective drainage and a credible pattern of movement occur together. A Level 3 Survey should assess the visible evidence, explain its significance and recommend proportionate investigation where necessary. This allows the purchaser to make a decision based upon the property’s actual condition rather than fear arising from the presence of a tree alone.
Need Advice About Trees, Cracking or Structural Movement?
Rectory Surveyors Ltd undertakes Level 3 Surveys of houses and flats throughout London and the surrounding areas. Our surveys consider visible cracking, structural movement, drainage, surrounding ground and other factors affecting the property. To learn more about our RICS home-survey services, please visit:
For related guidance concerning location and environmental risks when purchasing a property, please visit:
Telephone: 020 7249 4954
Email: info@rectorysurveyors.co.uk
Rectory Surveyors are experts in building and surveying, friendly and experienced, with a high degree of professionalism for all your surveying requirements. Learn more >
T: 020 7249 4954
E: info@rectorysurveyors.co.uk
