Tree Roots, Clay & Ground Movement in Chichester

Major Causes of Ground Movement in Chichester

1. Tree Root Spread

Mature trees are common across Chichester, especially:

• Oaks in Bosham, Fishbourne & Apuldram
• Beech & sycamore in Lavant & Goodwood
• Willow near waterways around Hunston & Donnington

Tree roots can:

• Lift patios from below
• Displace retaining walls
• Crack driveways
• Absorb moisture, causing clay soils to shrink

When combined with poorly built sub-bases and drainage, even relatively small root systems can cause noticeable settlement or heave.

2. Clay Soil Shrink–Swell Cycle (Tangmere, Oving)

Clay expands when wet and contracts when dry, causing:

• Patios to lift in winter
• Driveways to crack in summer
• Walls to rotate or separate from footings
• Steps and paths to drift out of alignment

These movements are often amplified where trees are drawing moisture from the same clay band that supports your hard landscaping.

3. Sandy Soil Movement (Bosham, Fishbourne)

These soils drain well but do not provide natural lateral stability unless reinforced. Without geogrids or proper edge restraint, paths and new terraced garden areas can gradually spread and sink over time.

4. Chalk Cavities (Lavant, Goodwood)

Chalk is generally stable but may develop small voids or weaken when oversaturated. Thorough compaction and correctly designed drainage routes are essential to avoid localised collapse under patios and driveways.

How We Stabilise Ground for Landscaping

1. Deeper Excavations Around Trees

We dig past root zones where possible and install a fresh structural layer with a compacted Type 1 or Type 3 sub-base. Where roots are protected or too large to remove, we adapt the design rather than simply paving over the problem.

2. Root Barriers

Installed vertically to prevent lateral root spread into patios or driveways, particularly near boundary trees or willows close to waterways.

3. Type 3 Sub-Base on Clay

Type 3 aggregate allows drainage while maintaining structural integrity on clay soils, especially when combined with appropriate falls and edge details.

4. Geogrid Reinforcement for Weak or Sandy Ground

Especially useful in Bosham, Fishbourne and Apuldram, where sandy or made ground needs extra tensile strength beneath porcelain or sandstone paving.

5. Land Drains & French Drains

Used to control moisture movement around clay zones and to intercept water before it saturates sub-bases or foundations. These are designed alongside broader garden drainage strategies.

6. Concrete Strengthening for Retaining Walls

Includes:

• Rebar-reinforced footings
• RSJ steel systems for sleeper walls
• Drainage membranes and weep holes behind walls

This is particularly important where level changes and tree roots work together to push and rotate structures.

7. Full Mortar Installation for Patios

Prevents individual slabs from rocking as the ground shifts slightly. For porcelain, we always use full-bed mortar and priming slurry to minimise the risk of tiles debonding if the sub-base moves a little.

Recognising Signs of Root or Soil Movement

• Raised or uneven patio slabs near tree lines
• Driveway dips or bulges over old roots or soft spots
• Cracks in retaining walls or garden steps
• Surface water pooling in new areas after rain
• Soil pulling away from structures during very dry weather
• Steps lifting on one side, especially near hedges or trunks

Area-Specific Considerations

• Bosham: Coastal root systems + sandy movement on sloping plots
• Fishbourne: Tree-heavy, moisture-rich ground near the harbour edge
• Lavant: Chalk + sloping terrain where drainage paths matter
• Tangmere: Heavy clay shrink–swell behaviour beneath patios and drives
• Oving: Mixed soils → more unpredictable movement patterns
• Hunston / Donnington: Soft ground near waterways and ditches

Areas We Cover

Chichester · Bosham · Fishbourne · Lavant · Tangmere · Oving · Donnington · Hunston · Westhampnett · Goodwood · Apuldram · South Downs villages

Concerned About Ground Movement?

We assess root influence, soil behaviour and foundation depth to design long-lasting landscaping solutions, often tying tree-root management into planning rules for level changes and retaining walls where necessary.

Book a Site Assessment

Frequently Asked Questions About Tree Roots & Ground Movement

Can I build a patio close to a mature tree?

Yes, but the design needs to allow for roots and future movement. We typically adjust the layout, use root-friendly construction details and sometimes install barriers so the patio can move slightly without cracking or being lifted by large roots.

Do I need to remove trees before installing a new patio?

Not always. In many Chichester gardens we retain trees for shade and character while carefully managing root zones. We only recommend removal when the tree is unsafe, causing structural damage or clearly incompatible with your planned layout.

Will cutting tree roots damage the tree?

Cutting major roots can destabilise or stress a tree, especially on one side. Minor root trimming is often fine if planned carefully, but larger cuts should be assessed on a case-by-case basis and may require input from a tree surgeon or arboriculturist.

How far can clay movement travel from a tree?

On shrinkable clay, moisture changes can extend well beyond the canopy line — sometimes up to the mature height of the tree. That’s why we always look at the bigger picture around the property, not just the immediate patio footprint.

Chichester Landscaping Knowledge Hub

Explore all of our in-depth landscaping guides for Chichester · Bosham · Fishbourne · Lavant · Tangmere · Oving · Donnington · Hunston · Apuldram · Goodwood · Westhampnett · South Downs villages:

Start a Conversation