← All guides · Rules & boundary law · Updated October 2026

Hedge roots and clay shrinkage in Gravesend: the common law nuisance duty before you plant or remove

The question most people don't ask until the cracking starts: if your boundary hedge is drawing moisture from shrinkable clay beneath your neighbour's foundations, are you liable? On shrinkable clay soils, the answer can be yes. A line of caselaw running from a 1967 Privy Council decision to a 2001 House of Lords ruling has hardened into a settled common law nuisance duty: if you know, or ought to know, that your hedge poses a foreseeable risk of root-related subsidence damage to a neighbouring structure, you are required to act. Understanding that duty before you plant a new hedge close to a boundary, or before you advise a client on renovating a mature one, is the starting point.

What the law says

The measured duty of care: Goldman v Hargrave and Leakey

The legal framework for root nuisance sits entirely in common law, not statute. The foundational authority is Goldman v Hargrave [1967] 1 AC 645, decided by the Privy Council on appeal from Australia. A tree on Goldman's land was struck by lightning and caught fire; he had it felled but left it to burn itself out rather than extinguishing it; the fire revived and spread to Hargrave's neighbouring property. The Privy Council held that a landowner owes neighbours a "measured duty of care" in respect of hazards arising naturally on the land, including living vegetation. The duty is not strict: it is calibrated to what is reasonable given the landowner's means and the actual risk. But it exists, and it is triggered by knowledge of the hazard.

The Court of Appeal confirmed the principle applies in England in Leakey v National Trust [1980] QB 485. Earth and debris from a natural mound on the Trust's land had for years slid down and damaged Leakey's cottage. The court held that once a landowner knows of a natural hazard with foreseeable potential to damage a neighbour's land, the duty to take reasonable steps to abate it arises. Ignorance of the hazard is a defence only until the point at which it ought reasonably to have been known: a hedge planted beside the boundary of a Victorian terrace on shrinkable clay, left untended for decades as roots spread deeper, creates a foreseeable risk that the hedge owner is taken to know.

Root desiccation of clay: Delaware Mansions

The case that directly addresses tree and hedge roots desiccating clay beneath a building is Delaware Mansions Ltd v Lord Mayor and Citizens of the City of Westminster [2001] UKHL 55. Roots from a plane tree on the highway had desiccated the clay subsoil beneath a residential block in Westminster, causing subsidence damage. The House of Lords held that this was an actionable nuisance. The key principle from that decision is:

• Knowledge and opportunity: once the responsible authority (or landowner) has been notified of the encroaching roots and given a reasonable opportunity to abate the nuisance, and fails to do so, the claimant is entitled to carry out the necessary remediation work and recover the reasonable cost. Failure to notify does not automatically defeat the claim, but notification is the cleaner route to recovery.

The Delaware Mansions decision was given in the context of a highway authority's tree, but the principles it confirms from Goldman and Leakey apply equally to a private landowner's hedge. A claimant seeking damages for subsidence caused by a neighbour's boundary hedge on shrinkable clay would be working with those same authorities.

What the High Hedges regime does not cover

Part 8 of the Anti-Social Behaviour Act 2003 gives local councils the power to resolve disputes about high hedges that are blocking light or outlook. It is a statutory complaint procedure with a fee set by the council. It is important to understand what it does not cover: the Act and its statutory guidance make clear that councils cannot deal with problems caused by roots. Gravesham Borough Council considering a high-hedge complaint has no power under Part 8 to order root work, award compensation for subsidence damage, or require a hedge to be removed on grounds that its roots threaten a neighbour's foundations. The statutory route for root damage is a civil claim in nuisance, not a high-hedge complaint. This is a common misunderstanding, and it matters: submitting a high-hedge complaint when the real problem is subsidence from roots wastes time and the complaint fee, and does not resolve the underlying liability position.

Step-by-step: the legal position from planting to complaint

Step 1: Identify whether you are on shrinkable clay

Clay soils that shrink in dry weather and swell when wet are the ones that cause root-related subsidence. Some parts of the borough have clay-rich ground and others sit on chalk, sand or gravel, so the only reliable way to know is a site investigation, the British Geological Survey's maps for your address, or advice from a structural engineer. If your hedge sits on shrinkable clay and a neighbour's building lies close to the hedge line, the conditions for root desiccation subsidence are physically present.

Chalk and free-draining soils do not shrink in the same way, so the same hedge beside a building on chalk presents a different physical risk from the same species beside a building on clay.

Step 2: Know which species extract the most moisture

Not all plants draw the same amount of water from the soil. Large, fast-growing plants draw the most, and a hedge that is allowed to grow tall draws more than one kept tightly clipped. NHBC guidance rates water demand by species, and for hedges the biggest single variable is usually how large the plant is allowed to grow.

When I look at a hedge near an older terrace, the species and age of the hedge are part of the first look. A thick privet boundary that has been there for decades, with roots that have had time to reach a footing, is a different proposition to a newly planted native hedge in the same spot.

Step 3: Before planting a new hedge close to a boundary on clay, check proximity to buildings

Risk generally rises as the distance between a plant and a building falls below the plant's mature height, but the real answer depends on the soil, the species and the foundations. This is a practical screening idea, not a legal bright line. If a building is close to the planting line on shrinkable clay, get advice from a structural engineer or an arboricultural consultant before planting.

A root barrier is sometimes used as a precaution when planting near a building. It does not make the risk disappear and is no substitute for distance, but it can show that you took reasonable steps at the outset.

Step 4: If you receive a complaint about subsidence, act on it promptly in writing

The Delaware Mansions principle establishes that notification of a root nuisance, followed by opportunity to remedy and failure to do so, is the route to full cost recovery for the claimant. This means the risk to you as the hedge owner is not resolved by silence after a complaint. If a neighbour writes to you claiming that your boundary hedge is causing subsidence damage and asking you to cut roots or remove the hedge, that letter starts the clock running on your opportunity to respond.

The appropriate response is not to ignore the letter or simply say you dispute it. The measured duty of care requires that you take the complaint seriously, investigate whether the risk is foreseeable given the location and species, and take reasonable steps proportionate to your means if it is. A written reply acknowledging the complaint and explaining what steps you are taking or commissioning protects you from the most damaging part of the Delaware Mansions position: the scenario where a court finds that you were notified, given a reasonable opportunity to act, did nothing, and are therefore liable for all the remediation costs the claimant incurred.

Step 5: Before removing an established hedge on clay, consider the risk of heave

Why clay soils matter

Clay-rich soils shrink in dry summers and swell back in wet winters, with the greatest movement in the upper couple of metres. Older houses on shallow foundations sit entirely within that layer, which is why they are the ones most often affected.

Insurers and surveyors treat the proximity of established trees and hedges to buildings on shrinkable clay as a risk factor, and subsidence claims rise in drought years. Newer houses built to current foundation standards are generally at lower risk than older ones.

Where the soil is chalk, sand or gravel, the risk profile changes with it.

What "reasonable steps" means in practice

The Goldman and Leakey cases calibrate the duty to what is reasonable given the landowner's means and the nature of the hazard. This is not a strict liability standard: you are not automatically liable for every crack caused by every root near your boundary. What the cases require is that, once the risk is known or ought reasonably to be known, you do not simply ignore it.

In practice, across the range of jobs I encounter in Gravesend and Northfleet, "reasonable steps" typically means one or more of the following, depending on the specific situation:

• Annual or biennial hard cutting of the hedge to reduce its active leaf area and therefore its moisture demand, particularly through dry summers. A hedge cut to 1.5 metres and kept tightly clipped extracts significantly less soil moisture than the same species left to grow to 3 metres.
• Root pruning at the boundary line to intercept lateral root growth before it crosses beneath a footing. This is a specialist operation and should be assessed before any significant root disturbance, since severing major structural roots close to the base of a hedge can destabilise stems and create a wind-throw risk.
• Commissioning an arboricultural consultant's report to assess root extent and condition if a neighbour's complaint is documented and credible. The cost of a report is manageable; the cost of defending a subsidence claim without one is not.
• Staged removal where the hedge presents a sustained, documented risk and less invasive management has not resolved it, with a structural engineer's advice on heave risk beforehand.

None of these steps requires you to spend money you cannot afford. The measured duty of care is calibrated to your means, not to an absolute standard. But it does require you to engage with the problem in good faith rather than deny it.

Sources: Goldman v Hargrave [1967] 1 AC 645 (Privy Council); Leakey v National Trust for Places of Historic Interest or Natural Beauty [1980] QB 485 (Court of Appeal); Delaware Mansions Ltd v Lord Mayor and Citizens of the City of Westminster [2001] UKHL 55 (House of Lords, judgment at parliament.uk); Anti-Social Behaviour Act 2003, Part 8, section 66(1) (legislation.gov.uk); Wildlife and Countryside Act 1981, section 1 (legislation.gov.uk); Town and Country Planning (Tree Preservation) (England) Regulations 2012; Building Research Establishment, "Soils and vegetation: assessing the potential for swelling and shrinkage" (BRE Digest 240); National House-Building Council (NHBC) Standards Chapter 4.2 (Building near trees); Association of British Insurers, subsidence guidance for mortgage lenders (abi.org.uk); British Geological Survey, GeoIndex, soil shrinkability mapping for north Kent (bgs.ac.uk).