24 Aug Planning Building Work Around Existing Trees: What You Need to Know
Mature trees can add character, privacy and environmental value to a property. However, they can also create additional considerations when planning an extension, basement, new structure or major landscaping project.
Building near a tree does not automatically mean it needs to be removed. Most trees growing close to properties cause no damage, but their roots, water demand and legal status should be assessed before designs are finalised or excavation begins.
Early surveys and careful planning can help protect the tree, safeguard your property and reduce the risk of delays, redesigns and unexpected structural problems.
Why Trees Matter During Building Work
Tree roots absorb water and nutrients, anchor the tree and often extend much further than the visible canopy. The Royal Horticultural Society advises that roots can spread as far as three times the height of a tree, meaning the area requiring assessment may be larger than expected.
Construction can affect trees through:
- Excavation for foundations, drainage and services
- Soil compaction from machinery or stored materials
- Changes to ground levels
- Root cutting or damage
- Alterations to natural drainage
Trees may also affect buildings indirectly. On shrinkable clay soils, roots can draw moisture from the ground during dry periods, causing the soil to contract. This can contribute to movement beneath shallow or vulnerable foundations.
Arrange a Tree Survey Early
Trees should be assessed before the building footprint and foundation design are confirmed.
An arboricultural survey can record the location, species, size, condition and expected lifespan of trees on or near the site. This may include neighbouring trees where their roots or canopies could be affected by the proposed work.
The survey can also identify the tree’s Root Protection Area: the space around it where roots and soil should normally be protected from excavation, compaction and other construction activity.
Involving an arboriculturist early gives your architect, engineer and contractor the information needed to develop a practical design.
Check Whether Trees Are Protected
Before pruning branches, cutting roots or removing a tree, check whether it is protected by a Tree Preservation Order.
Consent from the local planning authority is normally required before carrying out work to a protected tree, unless an exemption applies. Trees within conservation areas may also be protected, and the council may need six weeks’ notice before certain work begins.
Planning permission for a building project should not be treated as automatic approval for unrelated tree work. Planning conditions may also require specific protection measures or inspections during construction.
Checking these requirements at the start can prevent delays, enforcement action and changes to the construction programme.
Design Around the Site Conditions
Once the trees and ground conditions are understood, the proposed design can be reviewed properly.
This may affect:
- The position or size of the structure
- Foundation type and depth
- Drainage and service routes
- Machinery access
- Ground levels and hard landscaping
- Material storage areas
Soil type is particularly important. Buildings on clay-rich ground may require deeper or specially designed foundations to account for nearby vegetation. Older properties may also have shallower foundations that are more vulnerable to ground movement.
Depending on the site, suitable solutions may include deeper foundations, piling, ground beams or carefully controlled excavation.
Protect Roots During Construction
A suitable design will only be effective if the agreed protection measures are followed on site.
Root Protection Areas should be clearly marked before machinery and materials arrive. Protective fencing, ground protection systems and defined access routes may be required.
Protected areas should not be used for:
- Parking vehicles
- Storing soil or building materials
- Mixing concrete
- Lighting fires
- Discharging chemicals or contaminated water
- Excavating trenches without approval
Everyone working on the project should understand the tree protection plan, including builders, subcontractors and delivery drivers.
Plan Drainage and Services Carefully
Drainage should form part of the early site assessment.
Roots do not normally break into sound drains, but they may enter through existing cracks or defective joints. New drainage trenches can also damage important roots if routes are not planned carefully.
Where possible, services should be positioned outside protected rooting areas. If this is not practical, specialist installation methods may be needed to reduce excavation and disturbance.
Existing drains should also be inspected where structural movement is suspected. Leaking drainage, poor ground conditions and inadequate foundations can all contribute to cracking, so a nearby tree should not automatically be assumed to be the cause.
Avoid Removing Trees Without Advice
Removing a tree may appear to be the simplest solution, but it can create additional risks.
On clay soils, a mature tree may have affected moisture levels for many years. Removing it can allow the ground to absorb more water and expand, potentially contributing to heave beneath foundations.
Professional advice can help establish whether a tree is genuinely causing damage and whether pruning, monitoring, root management or structural work would be more appropriate.
The Association of British Insurers reported that insurers supported almost 9,000 UK households with subsidence damage during the first half of 2025. Claims totalled £153 million, with an average payout of more than £17,000. These figures highlight the importance of assessing vegetation, drainage, soil and foundations together.
Plan Early and Build with Confidence
Existing trees do not have to prevent you from extending or improving your property. However, they should be considered from the earliest design stages.
A professional survey, suitable foundation design, clear protection measures and careful site planning can reduce risk and help the project run smoothly. Where roots present a genuine concern, a properly designed tree root barrier may provide an effective alternative to removing the tree.
How U&M Group Can Support Your Project
At U&M Group, we understand that building around existing trees requires a site-specific approach.
We support homeowners, developers and property professionals with thorough site planning and specialist tree root management. Our services include professionally designed and installed tree root barriers, which can help redirect root growth away from buildings, drainage systems, driveways and other vulnerable areas.
With more than 20 years’ experience in root barrier installation, we aim to provide practical solutions that protect properties while helping preserve valuable, mature trees wherever possible.
Contact us today for specialist advice on tree root barriers, site planning, piling, underpinning and structural solutions.