Dr Giles Biddle and

Dr Martin Dobson

GETTING TO GRIPS WITH GETTING TO GRIPS WITH SUBSIDENCESUBSIDENCE

Dr Martin Dobson

Introduction and background to Introduction and background to subsidence problemssubsidence problems

…when fashion sense was questionableand subsidence became an ‘insured peril’

Our story begins in the 1970s…Our story begins in the 1970s…

…which coincides with the first commercial flight of Concorde on 21 January

It continues in 1976…It continues in 1976…

…with the formation of Apple Computers on 1 April

…with water rationing in Cardiff on 9 August

The long hot summer The long hot summer of 1976 was the of 1976 was the longest recorded longest recorded

in England and Wales in England and Wales since 1727. since 1727.

19761976

19761976

Staines reservoirStaines reservoirFor several weeks For several weeks in July and August, in July and August, large parts of the large parts of the country got no country got no rainfall at all rainfall at all leading to the leading to the drying up of drying up of reservoirs and a reservoirs and a severe drought.severe drought.

19761976

Finally the Labour Finally the Labour government of the government of the time appointed a time appointed a

minister for minister for drought… drought…

……as if on cue the rain began to fall.as if on cue the rain began to fall.

Denis Howell

SUBSIDENCESUBSIDENCE

SUBSIDENCESUBSIDENCE

What kind of damage are we What kind of damage are we talking about?talking about?

0

50

100

150

200

250

300

350

400

450

500

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

Number of claims (1000s)

Cost of claims (£million)

Legal frameworkLegal framework

Case law (common law)

TrespassTrespass

TrespassTrespass

A trespass is the wrongful invasion of another's property.

Every unlawful entry onto another's

property is trespass, even if no harm is

done to the property

Trespassing root (naughty!)

NuisanceNuisance

NuisanceNuisance

Unfortunately trees can’t read!

NuisanceNuisance

A private nuisance is an interference with a person's enjoyment and use of his land.

NegligenceNegligence

A person has acted negligently if he/she has departed from the conduct expected of a reasonably prudent person acting under

similar circumstances

Reasonable ForeseeabilityReasonable Foreseeability

a danger which a reasonable person should anticipate as the result from his/her action or

inaction

Solloway v Hampshire County Council Solloway v Hampshire County Council (1981)(1981)

HCC were appealing against a previous judgement made against them in favour of a home owner Mr B. Solloway.

Subsidence damage had been caused to the house by a Horse Chestnut owned by HCC.

Judgement was made that the encroachment of the tree roots constituted a nuisance and HCC were responsible for damage caused.

However, geological maps showed that whilst the house was on plateau gravel sections of it rested on small pockets of clay which were not shown on geological maps.

The Court of Appeal ruled that the existence of small clay pockets beneath the house was not reasonably foreseeable and hence there was no breach of duty on the part of HCC. The appeal was allowed.

Paterson v Humberside County Council Paterson v Humberside County Council (1995)(1995)

Damage to a house caused by two Lime trees owned by Humberside County Council.

It was noted that although the house had shallow foundations and was thus more susceptible to damage this had no relevance to liability – ‘the tree takes its victim as it find it’

An argument was made on behalf of the plaintiffs that there was no need to establish foreseeability. This was rejected by the judge who said the test for such foreseeability was whether the risk was one which a reasonable person in the defendants position would have regarded as a real risk.

The Council was deemed to know that damage was a ‘real risk’ as it advised householders of safe distances from buildings to plant trees.

Delaware Mansions v Westminster City Delaware Mansions v Westminster City Council Council (1999)(1999)

In 1989 a Plane tree owned by Westminster City Council caused damage to some flats. Engineers recommended underpinning of the flats or removal of the tree. The council refused to remove the tree.

The flats were sold in June 1990 to the second appellant company for one pound. However, their claim for damages was dismissed on the grounds that they could not claim because the damage had occurred before they became the owners.

The plaintiffs appealed and won. "Thus, where there is a continuing nuisance, the owner is entitled to … damages "

"If the council had agreed to remove the tree when asked, the damages would have been very small…the fact that the nuisance existed before the second appellant became the owner is irrelevant".

Jones v Portsmouth City Council Jones v Portsmouth City Council (2002)(2002)

The key issues were whether subsidence had been caused by the defendant’s Plane trees, whether the council were responsible and whether or not the council had been given sufficient notice to abate the nuisance.

The judge ruled that the trees had caused damage and that despite the soil being ‘brick earth’ it was a foreseeably shrinkable soil.

On the matter of reasonable notice to abate the judge said: ‘the fact is that the defendant was notified of the claim before the claimant was committed by contract to the underpinning ’ and therefore ‘the defendant was not deprived of a reasonable opportunity to abate the nuisance’ .

Loftus Brigham v London Borough of Loftus Brigham v London Borough of Ealing Ealing (2003)(2003)

The issue was subsidence caused by either the claimant’s Virginia creeper and/or Wisteria or the defendant’s Plane trees Original ruling - ‘The Claimants need to show that the Defendants’ trees were probably the dominant cause and they have not convinced me that such was established’

On Appeal the ruling was that the proper test was whether the tree roots were the ‘effective and substantial’ cause of the damage or alternatively whether they ‘materially contributed to the damage’.

Raphael v London Borough of Brent Raphael v London Borough of Brent (2007)(2007)

The issue was whether level monitoring only was adequate to establish that subsidence had occurred.

There were no soil, foundation or root investigations. Neither was any crack monitoring carried out.

The secondary issue was which vegetation caused the damage. Was it the claimant’s Wisteria and Cherry or the council’s Plane(s)?

The judge ruled out the claimant’s vegetation as a cause of damage and gave judgement against the council.

CHERRY

PLANE

London Tree Officer’s Association London Tree Officer’s Association

Identify those trees that are most likely to Identify those trees that are most likely to cause subsidence damage and subject cause subsidence damage and subject them to a regular and systematic pruning them to a regular and systematic pruning regime.regime.

Make the identification of the above trees an on goingMake the identification of the above trees an on going process process within the normal tree inspection programme.within the normal tree inspection programme.

Investigate all potential subsidence claims that may implicate Investigate all potential subsidence claims that may implicate trees and take prompt action (i.e. investigate the site and, if trees and take prompt action (i.e. investigate the site and, if appropriate, carry out precautionary pruning). If ground appropriate, carry out precautionary pruning). If ground conditions recover subsequent to precautionary pruning the conditions recover subsequent to precautionary pruning the potential claim may not be lodged. By taking prompt action potential claim may not be lodged. By taking prompt action boroughs can eliminate or mitigate a potential claim.boroughs can eliminate or mitigate a potential claim.

All claims should be assessed and remedial pruning carried out All claims should be assessed and remedial pruning carried out as soon as practically possible, except where the claims are as soon as practically possible, except where the claims are clearly unreasonable or erroneous.clearly unreasonable or erroneous.

Before undertaking further pruning or contemplating tree removal Before undertaking further pruning or contemplating tree removal the authority should insist that the claimant provide adequate the authority should insist that the claimant provide adequate evidence in support of the claim.evidence in support of the claim.

Identify those trees that are most likely to cause subsidence Identify those trees that are most likely to cause subsidence damage and subject them to a regular and systematic pruning damage and subject them to a regular and systematic pruning regime.regime.

Make the identification of the above trees Make the identification of the above trees an on goingan on going process within the normal process within the normal tree inspection programme.tree inspection programme.

Investigate all potential subsidence claims that may implicate Investigate all potential subsidence claims that may implicate trees and take prompt action (i.e. investigate the site and, if trees and take prompt action (i.e. investigate the site and, if appropriate, carry out precautionary pruning). If ground appropriate, carry out precautionary pruning). If ground conditions recover subsequent to precautionary pruning the conditions recover subsequent to precautionary pruning the potential claim may not be lodged. By taking prompt action potential claim may not be lodged. By taking prompt action boroughs can eliminate or mitigate a potential claim.boroughs can eliminate or mitigate a potential claim.

All claims should be assessed and remedial pruning carried out All claims should be assessed and remedial pruning carried out as soon as practically possible, except where the claims are as soon as practically possible, except where the claims are clearly unreasonable or erroneous.clearly unreasonable or erroneous.

Before undertaking further pruning or contemplating tree removal Before undertaking further pruning or contemplating tree removal the authority should insist that the claimant provide adequate the authority should insist that the claimant provide adequate evidence in support of the claim.evidence in support of the claim.

Identify those trees that are most likely to cause subsidence Identify those trees that are most likely to cause subsidence damage and subject them to a regular and systematic pruning damage and subject them to a regular and systematic pruning regime.regime.

Make the identification of the above trees an on goingMake the identification of the above trees an on going process process within the normal tree inspection programme.within the normal tree inspection programme.

Investigate all potential subsidence claims Investigate all potential subsidence claims that may implicate trees and take prompt that may implicate trees and take prompt action (i.e. investigate the site and, if action (i.e. investigate the site and, if appropriate, carry out precautionary pruning). appropriate, carry out precautionary pruning). If ground conditions recover subsequent to If ground conditions recover subsequent to precautionary pruning the potential claim precautionary pruning the potential claim may not be lodged. may not be lodged.

All claims should be assessed and remedial pruning carried out All claims should be assessed and remedial pruning carried out as soon as practically possible, except where the claims are as soon as practically possible, except where the claims are clearly unreasonable or erroneous.clearly unreasonable or erroneous.

Before undertaking further pruning or contemplating tree removal Before undertaking further pruning or contemplating tree removal the authority should insist that the claimant provide adequate the authority should insist that the claimant provide adequate evidence in support of the claim.evidence in support of the claim.

Identify those trees that are most likely to cause subsidence Identify those trees that are most likely to cause subsidence damage and subject them to a regular and systematic pruning damage and subject them to a regular and systematic pruning regime.regime.

Make the identification of the above trees an on goingMake the identification of the above trees an on going process process within the normal tree inspection programme.within the normal tree inspection programme.

Investigate all potential subsidence claims that may implicate Investigate all potential subsidence claims that may implicate trees and take prompt action (i.e. investigate the site and, if trees and take prompt action (i.e. investigate the site and, if appropriate, carry out precautionary pruning). If ground appropriate, carry out precautionary pruning). If ground conditions recover subsequent to precautionary pruning the conditions recover subsequent to precautionary pruning the potential claim may not be lodged. potential claim may not be lodged.

All claims should be assessed and All claims should be assessed and remedial pruning carried out as soon as remedial pruning carried out as soon as practically possible, except where the practically possible, except where the claims are clearly unreasonable or claims are clearly unreasonable or erroneous.erroneous.

Before undertaking further pruning or contemplating tree removal Before undertaking further pruning or contemplating tree removal the authority should insist that the claimant provide adequate the authority should insist that the claimant provide adequate evidence in support of the claim.evidence in support of the claim.

Identify those trees that are most likely to cause subsidence Identify those trees that are most likely to cause subsidence damage and subject them to a regular and systematic pruning damage and subject them to a regular and systematic pruning regime.regime.

Make the identification of the above trees an on goingMake the identification of the above trees an on going process process within the normal tree inspection programme.within the normal tree inspection programme.

Investigate all potential subsidence claims that may implicate Investigate all potential subsidence claims that may implicate trees and take prompt action (i.e. investigate the site and, if trees and take prompt action (i.e. investigate the site and, if appropriate, carry out precautionary pruning). If ground appropriate, carry out precautionary pruning). If ground conditions recover subsequent to precautionary pruning the conditions recover subsequent to precautionary pruning the potential claim may not be lodged. potential claim may not be lodged.

All claims should be assessed and remedial pruning carried out All claims should be assessed and remedial pruning carried out as soon as practically possible, except where the claims are as soon as practically possible, except where the claims are clearly unreasonable or erroneous.clearly unreasonable or erroneous.

Before undertaking further pruning or Before undertaking further pruning or contemplating tree removal the authority contemplating tree removal the authority should insist that the claimant provide should insist that the claimant provide adequate evidence in support of the adequate evidence in support of the claim.claim.

Joint Mitigation ProtocolJoint Mitigation Protocol

May 2008May 2008Aims to:

Speed up the process of claims handling, decision making and mitigation implementation leading to resolution

Recognise the value of trees in the built environment

Provide local authorities with all the investigative evidence required at the beginning of the process.

Joint Mitigation ProtocolJoint Mitigation Protocol

May 2008May 20087 days notify tree owner of damage

14 days after receipt of notification tree owner to supply details of:

- Contact person- Insurer- CAVAT value of tree - low (less than £5,300) medium (£5,300 to £17,500) high (greater than

£17,500).

60 days submission of evidence in support of claim

13 weeks from receipt of the evidence to undertake the mitigation.

ABI DOMESTIC SUBSIDENCE TREE ROOT CLAIMS ABI DOMESTIC SUBSIDENCE TREE ROOT CLAIMS AGREEMENTAGREEMENT

THIRD PARTY LIABILITYTHIRD PARTY LIABILITY

Every insurer subscribing to this Agreement agrees -Every insurer subscribing to this Agreement agrees -

11 that where a claim arises in respect of subsidence that where a claim arises in respect of subsidence and where damage to the building and/or contents has and where damage to the building and/or contents has been caused wholly or partly by tree root encroachment been caused wholly or partly by tree root encroachment the insurer holding the buildings and/or contents the insurer holding the buildings and/or contents insurance for the damaged property undertakes to insurance for the damaged property undertakes to investigate, handle and where appropriate meet the investigate, handle and where appropriate meet the claim on the basis of their policy cover;claim on the basis of their policy cover;

22 not to pursue recovery against the insurers of the owned/tenanted/ occupied property responsible not to pursue recovery against the insurers of the owned/tenanted/ occupied property responsible for the liability of the tree root encroachment regardless of whether the damage has been caused wholly or partly for the liability of the tree root encroachment regardless of whether the damage has been caused wholly or partly as a result of the tree root encroachment;as a result of the tree root encroachment;

33 that in the event of there being a recurrence of damage or no reasonable preventative measures that in the event of there being a recurrence of damage or no reasonable preventative measures being taken by the person/persons who have liability for the tree root encroachment this Agreement will have no being taken by the person/persons who have liability for the tree root encroachment this Agreement will have no effect in regard to any subsequent claim.effect in regard to any subsequent claim.

44 that this Agreement will have no bearing or consideration in any uninsured loss claim which may be that this Agreement will have no bearing or consideration in any uninsured loss claim which may be pursued against the person/persons having a potential liability for the tree root encroachment". pursued against the person/persons having a potential liability for the tree root encroachment".

ABI DOMESTIC SUBSIDENCE TREE ROOT CLAIMS ABI DOMESTIC SUBSIDENCE TREE ROOT CLAIMS AGREEMENTAGREEMENT

THIRD PARTY LIABILITYTHIRD PARTY LIABILITY

Every insurer subscribing to this Agreement agrees -Every insurer subscribing to this Agreement agrees -

11 that where a claim arises in respect of subsidence and where damage to the building and/or that where a claim arises in respect of subsidence and where damage to the building and/or contents has been caused wholly or partly by tree root encroachment the insurer holding the buildings and/or contents has been caused wholly or partly by tree root encroachment the insurer holding the buildings and/or contents insurance for the damaged property undertakes to investigate, handle and where appropriate meet the contents insurance for the damaged property undertakes to investigate, handle and where appropriate meet the claim on the basis of their policy cover;claim on the basis of their policy cover;

22 not to pursue recovery against the insurers of the not to pursue recovery against the insurers of the owned/tenanted/ occupied property responsible for the owned/tenanted/ occupied property responsible for the liability of the tree root encroachment regardless of liability of the tree root encroachment regardless of whether the damage has been caused wholly or partly whether the damage has been caused wholly or partly as a result of the tree root encroachment;as a result of the tree root encroachment;

33 that in the event of there being a recurrence of damage or no reasonable preventative measures that in the event of there being a recurrence of damage or no reasonable preventative measures being taken by the person/persons who have liability for the tree root encroachment this Agreement will have no being taken by the person/persons who have liability for the tree root encroachment this Agreement will have no effect in regard to any subsequent claim.effect in regard to any subsequent claim.

44 that this Agreement will have no bearing or consideration in any uninsured loss claim which may be that this Agreement will have no bearing or consideration in any uninsured loss claim which may be pursued against the person/persons having a potential liability for the tree root encroachment". pursued against the person/persons having a potential liability for the tree root encroachment".

ABI DOMESTIC SUBSIDENCE TREE ROOT CLAIMS ABI DOMESTIC SUBSIDENCE TREE ROOT CLAIMS AGREEMENTAGREEMENT

THIRD PARTY LIABILITYTHIRD PARTY LIABILITY

Every insurer subscribing to this Agreement agrees -Every insurer subscribing to this Agreement agrees -

11 that where a claim arises in respect of subsidence and where damage to the building and/or that where a claim arises in respect of subsidence and where damage to the building and/or contents has been caused wholly or partly by tree root encroachment the insurer holding the buildings and/or contents has been caused wholly or partly by tree root encroachment the insurer holding the buildings and/or contents insurance for the damaged property undertakes to investigate, handle and where appropriate meet the contents insurance for the damaged property undertakes to investigate, handle and where appropriate meet the claim on the basis of their policy cover;claim on the basis of their policy cover;

22 not to pursue recovery against the insurers of the owned/tenanted/ occupied property responsible not to pursue recovery against the insurers of the owned/tenanted/ occupied property responsible for the liability of the tree root encroachment regardless of whether the damage has been caused wholly or partly for the liability of the tree root encroachment regardless of whether the damage has been caused wholly or partly as a result of the tree root encroachment;as a result of the tree root encroachment;

33 that in the event of there being a recurrence of that in the event of there being a recurrence of damage or no reasonable preventative measures being damage or no reasonable preventative measures being taken by the person/persons who have liability for the taken by the person/persons who have liability for the tree root encroachment this Agreement will have no tree root encroachment this Agreement will have no effect in regard to any subsequent claim.effect in regard to any subsequent claim.

44 that this Agreement will have no bearing or consideration in any uninsured loss claim which may be that this Agreement will have no bearing or consideration in any uninsured loss claim which may be pursued against the person/persons having a potential liability for the tree root encroachment". pursued against the person/persons having a potential liability for the tree root encroachment".

ABI DOMESTIC SUBSIDENCE TREE ROOT CLAIMS ABI DOMESTIC SUBSIDENCE TREE ROOT CLAIMS AGREEMENTAGREEMENT

THIRD PARTY LIABILITYTHIRD PARTY LIABILITY

Every insurer subscribing to this Agreement agrees -Every insurer subscribing to this Agreement agrees - 11 that where a claim arises in respect of subsidence and where damage to the building and/or contents has been caused wholly or that where a claim arises in respect of subsidence and where damage to the building and/or contents has been caused wholly or

partly by tree root encroachment the insurer holding the buildings and/or contents insurance for the damaged property undertakes to investigate, partly by tree root encroachment the insurer holding the buildings and/or contents insurance for the damaged property undertakes to investigate, handle and where appropriate meet the claim on the basis of their policy cover;handle and where appropriate meet the claim on the basis of their policy cover;

22 not to pursue recovery against the insurers of the owned/tenanted/ occupied property responsible for the liability of the tree root not to pursue recovery against the insurers of the owned/tenanted/ occupied property responsible for the liability of the tree root encroachment regardless of whether the damage has been caused wholly or partly as a result of the tree root encroachment;encroachment regardless of whether the damage has been caused wholly or partly as a result of the tree root encroachment;

33 that in the event of there being a recurrence of damage or no reasonable preventative measures being taken by the person/persons that in the event of there being a recurrence of damage or no reasonable preventative measures being taken by the person/persons who have liability for the tree root encroachment this Agreement will have no effect in regard to any subsequent claim.who have liability for the tree root encroachment this Agreement will have no effect in regard to any subsequent claim.

44 that this Agreement will have no bearing or that this Agreement will have no bearing or consideration in any uninsured loss claim which may be consideration in any uninsured loss claim which may be pursued against the person/persons having a potential pursued against the person/persons having a potential liability for the tree root encroachment". liability for the tree root encroachment". Provided that:Provided that:(i)(i) Immediate notice shall be given to the other Immediate notice shall be given to the other insurer by the insurer to whom the claim is notified, insurer by the insurer to whom the claim is notified, together with copies of all relevant reports (including together with copies of all relevant reports (including covering letters) from loss adjusters, engineers, covering letters) from loss adjusters, engineers, surveyors and the like.surveyors and the like.

Subsidence risk assessmentSubsidence risk assessment

SRA developed by the Arboricultural Association in 1998 in response to requests by the mortgage

and insurance industry

Withdrawn in 2001 as it didn’t accurately predict subsidence risk

Subsidence risk assessmentSubsidence risk assessment

Subsidence risk assessmentSubsidence risk assessment

Subsidence risk assessmentSubsidence risk assessment

SRA developed by Royal and Sun Alliance

TreeRAT

Subsidence risk assessmentSubsidence risk assessment

6th September 2006 –new subsidence risk model, Arborisk™, for Greater London (woo hoo!)

Aerial photography and Infoterra’s lidar1 height data has been used to establish the proximity of trees to properties, as well as the height and canopy size – from which the current and future size of the root zone can be determined.

With this tree root zone data and soil type data, also included, the model can quickly produce accurate (?) subsidence risk assessments for individual properties.