Case law and guidance publications for:

Delay and disruption - the distinction

Quantification of loss caused by delay:

- Preliminaries

- Off-site / head-office overheads and profit

Quantification of loss caused by disruption:

- What is disruption

- Causes of disruption

- Proving disruption

- Methods of calculating disruption costs

Global claims for delay and/or disruption:

- What is a global claim?

- Are global claims permissible

- Proving a global claim

- Proof of causation

- Apportionment

- Obligation to prove causation


Delay and disruption – the distinction

Bell BCI Company v United States, Fed CL No 03-1613C (2006) at 4

“There is a distinction between (1) a “delay” claim and (2) “disruption” or cumulative impact claim. Although the two claim types often arise together in the same project, a “delay” claim captures the time and cost of not being able to work, while a “disruption” claim captures the cost of working less efficiently than planned”

Delay and Disruption Protocol (2nd ed, Society of Construction Law, 2017) paragraph 18.1

“Disruption (as distinct from delay) is a disturbance, hindrance or interruption to a Contractor’s normal working methods, resulting in lower efficiency. Disruption claims relate to loss of productivity in the execution of particular work activities. Because of the disruption, these work activities are not able to be carried out as efficiently as reasonably planned (or as possible). The loss and expense resulting from that loss of productivity may be compensable where it was caused by disruption events for which the other party is contractually responsible.”

Van Oard UK Ltd v Allseas UK Ltd [2015] EWHC 3074; RWE Npower PLC v Alstom Power Ltd (2009) WL 5641217

The courts are sometimes faced with combined claims for loss and expense due to delay and disruption which can require separation.


Quantification of loss caused by delay: preliminaries / site overheads

Approaches to assess delayed preliminaries / site overheads

The following six approaches can be used:

  1. Global pro-rata approach;

  2. Planned versus actual approach;

  3. Modified planned versus actual approach;

  4. Weighted average delay rate approach;

  5. Delay rate per-day approach; and

  6. Resource-by-resource ‘but for’ approach.

Refer to article DD19 'Quantifying delay costs - preliminaries - approaches to assess a contractor's entitlement' in blog page of the DD Quantum Expert website. 

Relevant case law and guidance publications

Williams v Strait 728 F Supp 12 (DCC 1990) at [28]

The court held that a contractor which did not demonstrate when each piece of equipment arrived at and left site was unable to recover the additional hire costs.

“This court finds that although [the contractor] is not required to prove with accuracy the amount of damages, it failed to establish a reasonable estimate for such items. [The contractor] omits a crucial element in its damage calculations for these items, namely when each piece of equipment arrived and left the site. Moreover, it is quite possible that these same items were used in some other aspect of the construction subsequent to the steel frame collapse. It is unclear from the evidence presented that these items were used solely for the purpose of the erection of the structural steel frame.”

Shore & Horwitz Construction Co Ltd v Franki of Canada Ltd [1964] SCR 589 (CanSC)

During a period of delay, plant and equipment may lie idle. The loss to the contractor in this situation may be the hire charges if the contractor hired the plant and equipment.

Alfred McAlpine Homes North Ltd v Property and Land Contractors Ltd (1995) 76 BLR 59

The contractor may own the idle plant and equipment. In this situation, the contractor must demonstrate that it lost the opportunity to hire out the affected plant and/or equipment for the period for which the claim is being made.

If the contractor is unable to prove that it lost the opportunity to hire out the claimed plant and/or equipment, its claim will be based on factors such as loss of interest on idle capital, maintenance and/or depreciation.

Sunley (B) & Co Ltd v Cunard White Star Ltd [1940] 1KB 740

Plant was owned by the contractor and the costs in relation to its delay claim for plant was limited to the “depreciation costs”.

Laburnum Construction Corporation v United States 163 Ct 339 (1964)

The fair rental value of contractor-owned equipment which stood idle because of employer-caused delays was held to be the correct basis for a claim for damages. It was held that the value should be reduced by 50% due to there being no wear and tear.

McAlpine Homes North Ltd v Property and Land Contractors Ltd (1995) 76 BLR 59 at 92

If the contractor owned the plant and therefore does not incur a hire charge, it is not correct to claim loss and expense by reference to hire charge rates.

Ascon Contracting Ltd v Alfred McAlpine Construction Isle of Man Ltd 1999 WL 1610677


Quantification of loss caused by delay: off-site overheads / head office overheads & profit

Thiess Watkins White Construction Ltd v Commonwealth of Australia (1998) 14 BCL 61

The court said that clause 35.4 of the contract referred to the contractor’s entitlement to ‘extra costs incurred’. The court considered that this refers to extra costs incurred by reason of delay as distinct from a ‘loss’ where the effect of the delay is that other work cannot be undertaken, and the contractor’s income is less. The court said that only the former are extra costs incurred. The latter is a loss (of opportunity) that did not fall under the definition of ‘extra cost’.

McAlpine Homes North Ltd v Property and Land Contractor Ltd (1995) 76 BLR 59 at 82

“… but modern office arrangements permit the recording of the time spent by managerial staff on particular projects.”

JF Finnegan Ltd v Sheffield City Council (1988) BLR 124 at 143

“It is generally accepted that, on principle, a contractor who is delayed in completing a contract due to the default of his employer, may properly have a claim for head office or off-site overheads during the period of delay, on the basis that the workforce, but for the delay, might have had the opportunity of being employed on another contract which would have had the effect of funding the overheads during the overrun period.”

Whittal Builders Co Ltd v Chester-le-Street DC

Whittal Builders applied the principle in JF Finnegan.

McAlpine Homes North Ltd v Property and Land Contractor Ltd (1995) 76 BLR 59

“The theory is that because the period of delay is uncertain and thus (the contractor) can take no steps to reduce its head office expenditure and other overhead costs and cannot obtain additional work there are no means whereby [the contractor] can avoid incurring the continuing head office expenditure, notwithstanding the reduction in turnover as a result of the suspension or delay to the progress of the work.

…If [the contractor’s] overall business is not diminished during the period of delay so that whether, for example, as a result of an increase in the volume of work on the contract in question arising from variations etc, … there will be a commensurate contribution towards the overheads which offsets any supposed loss, or if, as a result of other work, there is no reduction in overall turnover so that the costs of the fixed overhead continues to be met from other sources, there will be no loss attributable to the delay… this aspect is brought out in the comparable proposition that [the contractor] has to show that there were no means of reducing the unrecovered cost of the fixed overheads in the circumstances in which he found himself as a result of the events giving rise to the delay. Where [the contractor] is busy and is taking on work all the time it will probably not be possible to demonstrate the effect to which I have referred. Furthermore, it has to be borne in mind that as certain overheads are incurred through thick and thin, so [the contractor’s] head office staff may not always be constantly occupied because of, for example, the seasonal or cyclical nature of business in the construction industry.”

Sunley (B) & Co Ltd v Cunard White Star Ltd [1940] 1KB 740

The contractor must demonstrate, whether basing its calculation of loss on actual loss or by using a formula approach, that actual loss has been suffered, that is, the contractor must show that there has been a loss and that there was other work available which it would have secured but for the delay.

Hudson / Eichleay / Emden formulae[2]

None of the following formulae properly calculates actual loss and therefore should not be a contractor’s first choice.

Hudson formula

  • Ellis-Don Ltd v Parking Authority of Toronto (1987) 28 Build LR 98 at 124, 127

  • Beechwood Development Co (Scotland) Ltd v Stuart Mitchell [2001] Scot CS30

  • JF Finnegan Ltd v Sheffield City Council (1988) 43 BLR at 22 and 127

Eichleay formula

  • Eichleay Corporation ASBC No 5183 60-2 BCA 2,688 at [13,573]; affd Eichleay Corporation 61-1 BCA 12,894

  • Berley Industries Inc. v City of New York 45 NY 2d 685 (1978)

  • Capital Electric Co v United States 729 F 2d 743 (1984)

Emden Formula

  • Crown Office Chambers, Emden’s Construction Law (Lexis Nexis, subscription service)

Sunley (B) & Co Ltd v Cunard White Star Ltd [1940] 1KB 740 (CA)

For a contractor to make out a claim for loss of profit successfully, it will need to show that it could have used the lost income profitably.

Walter Lilly & Co Ltd v DMW Developments Ltd [2012] EWHC 1773 (TCC); [2012] BLR 503

Even if the contractor at the time is making a loss, the further loss incurred as a result of the delay would be recoverable.

In Walter Lilly, the court held that the use of a formula, supported by evidence of the lost opportunity, was a way to establish loss of profit. However, the court considered that to prove loss of profit, including loss of head office overheads, the contractor had to show that, on the balance of probabilities, that if there had been no delay it would have secured the work which would have contributed to the overheads and/or would have generated a profit and that the loss would not have been sustained.


Quantification of loss caused by disruption: what is disruption?

On construction projects, changes impact progress in many ways. Courts in the US have distinguished between “discrete” and “cumulative” types of impact on the progress of construction projects. 

Triple “A” South ASBCA 46866; 94-3 BCA 27,194 135 523 at [19]

"Local [or direct] disruption refers to the direct impact that changed work has on other unchanged work going on around it. Conceptually, for the purposes of this appeal “cumulative disruption” is the disruption which occurs between two or more change orders and basic work and is exclusive of that local disruption that can be ascribed to a specific change. It is the synergistic effect … of changes on the unchanged work and on other changes."

The timing and quantification of the impact of a change is difficult to measure and “measuring the impact of multiple, intertwined changes is even more difficult because there can be a compounding and amorphous effect… only becoming apparent in the late stages of a project when work cannot be completed on time.” 

Appeal of George Hayman Const. Co., E.N.G.B.C.A. No 4541, 85-1 B.C.A. (CCH) || 17847, at 89356, 1985 WL 16440 (Corps Eng’rs B.C.A. 1985) 

"It is generally recognised that certain conditions at construction job sites can prevent laborers from performing their tasks at a normal level of efficiency and that, therefore, the contractor will have to pay more to accomplish the same amount of work than he could reasonably have expected. A variety of causes may produce this result…

Proof of the amount of recovery for labor inefficiency is usually difficult and often somewhat speculative…"

Appeal of Centex Bateson Const. Co., Inc., V.A.B.C.A. No 4613, V.A.B.C.A. No. 5162, 99-1 B.C.A. (CCH) || 30153, 1998 WL 853085 (Veterans Admin. B.C.A. 1998), decision aff’d, 250 F.3d 761 (Fed. Cir. 2000): 

"Impact costs are additional costs occurring as a result of the loss of productivity; loss of productivity is also termed inefficiency. Thus, impact costs are simply increased labour costs that stem from the disruption to labor productivity resulting from change in working conditions caused by a contract change. Productivity is inversely proportional to the man-hours necessary to produce a given unit of product. As is self-evident, if productivity declines, the number of man-hours of labor to produce a given task will increase. If the number of man-hours increases, labor costs obviously increase."


Quantification of loss caused by disruption: causes of disruption

Delay and Disruption Protocol (2nd ed, Society of Construction Law, 2017), Guideline Part B: Guidance on Core Principles, [18.2]

“Disruption events can have a direct effect on the works by reducing productivity (such as piecemeal site access different from that planned, out of sequence works or design changes). They can also lead to secondary consequences on the execution of the works, for example through crowding of labor or stacking of trades, dilution of supervision through fragmented work gangs, excessive ovetime (which can lead to fatigue), repeated learning cycles and poor morale of labour which can further reduce productivity.”

AACE Recommended Practices: AACA International Recommended Practice No.25R-03: Estimating lost Labor Productivity in Construction Claims: TCM Framework: 6.4 – Forensic Performance Assessment (AACE, 2004), PP3-7

  • Absenteeism;

  • Acceleration (directed or constructive);

  • Adverse, or unusually severe, weather;

  • Availability of skilled labour;

  • Variations, ripple impact, cumulative impact of multiple changes, and rework;

  • Competition for labour;

  • Labour turnover;

  • Crowding of labour, or trade stacking;

  • Defective engineering, engineering recycle, or rework;

  • Dilution of supervision;

  • Excessive overtime;

  • Failure to co-ordinate trade contractors, subcontractors, or vendors;

  • Fatigue;

  • Labour relations and labour management factors;

  • Learning curve;

  • Material, tools and equipment shortages;

  • Over-manning;

  • Poor morale of labour force;

  • Project management factors;

  • Out-of-sequence work;

  • Rework and errors;

  • Schedule compression;

  • Site, or work area access restrictions;

  • Site conditions; and

  • Untimely approvals or responses.


Quantification of loss caused by disruption: proving disruption

McAlpine Humberon v McDermott International (1992) 58 BLR 1 at 28

The court said that the need for a retrospective and disectional reconstruction via expert evidence on an almost daily basis – analysing every drawing, technical query, and weld procedure to demonstrate whether a contractor had been disrupted by additional drawings – was “just what the case required”.

Walter Lilly & Co Ltd v DMW Developments Ltd [2012] EWHC 1773 (TCC); [2012] BLR 503 at 490

The court said that there is no set way to prove these elements and it is open to contractors to prove them with whatever evidence will satisfy the tribunal to the requisite standard of proof. However, even if such evidence is given, it is still necessary to assess the amount of disruption and the financial impact of that disruption.

The court accepted an approach that involved listing the relevant events relied upon, describing what additional or extended resources were deployed, and linking them to the causes of delay or disruption relied on. All the additional or extended resources were costed in an analysis which picked up allocations of time for staff and resources at particular times and applied to those allocations costs which were obtained from the contractor’s computerised record keeping system. The contractor also made allowances for its own inefficiencies.

Tate & Lyle Food and Distribution Ltd v Greater London Council [1982] 1 WLR 149

Do not apply an arbitrary percentage to labour costs.

Aerospace Publishing Ltd v Thomas Water Utilities Ltd (2007) 110 Con LR (CA)

Management staff may also experience disruption, e.g. where staff is diverted from normal duties. To prove the extent of disruption to management, it will be necessary to keep records of time spent on the project.

In Aerospace Publishing, the Court of Appeal concluded that a claim may fail on the basis that evidence that could be expected to be advanced was not advanced, which would have included evidence that the disruptive event caused disruption to the business.


Quantification of loss caused by disruption: the methods - overview

The measured mile method (continuous baseline)

Delay and Disruption Protocol (2nd ed, Society of Construction Law, 2017) Guidance Part B, Guidance on Core Principles

“Measured mile analysis: This compares the level of productivity achieved in areas or periods of the works impacted by identified disruption events with productivity achieved on identical or like activities in areas or periods of the works not impacted by those identified disruption events…”

Clark Concrete Contractors, Inc v General Services Administration GSBCA 14340; 99-1 BCA 30

“a measured mile analysis compares work performed in one period not impacted by events causing loss of productivity with the same, or comparable work performed in another period that was impacted by productivity-affected events.”

The baseline productivity method (intermittent baseline)

In summary, this method is similar to measured mile except:

  1. Calculate the baseline based on a subset of high-production work periods rather than use periods of good productivity.

A leading cause of a court rejecting a measured mile analysis is that the work performed in the undisrupted periods is not comparable. Conversion factors based on earned value concept are used to alleviate comparable problems.

Because calculating the baseline productivity does not require a continuous period of un-impacted work, the baseline productivity method is applicable to a wider range of project scenarios than the traditional measured mile method, even where a project is disrupted from the outset or throughout thereafter.

Total cost methods

Total unit cost method: costs incurred during the impacted and un-impacted periods are divided by the completed units of work. Deduct the non-labour costs. The difference in labour cost per unit installed should reflect the impact on labour productivity.

Total labour cost method: subtract the labour cost in the tender and in any change orders and claim settlements from the total labour cost expended. 

Project comparison studies

Comparable work method: there are two forms:

  1. Comparison of productivity in the impacted and un-impacted periods on the same project; and

  2. Comparison of productivity in the impacted period with productivity in an un-impacted period carried out by another contractor.

Comparable project method: comparison of productivity for a task on one project with the productivity of a same or similar task on another project. This method should only be used as a gauge.

General and speciality industry studies

Employs data from specific studies, e.g. could be used a gauge or a sense check or for future estimating purposes as a guide.

System dynamic modelling

A graphical illustration of a project which aims to simulate project performance as it is being built. Then the modelling simulates how the project would have been built had there been no changes.

Earned value analysis

The total number of hours estimated to complete a task comprises the “earned hours” and those hours are earned once the task is completed. The earned hours may be different to the actual hours. If the estimate of hours is correct, then the difference between the earned hours and actual hours, in theory at least, is the resultant positive or negative impact on productivity.


Global claims for delay and / or disruption

What is a global claim?

A contractor may decide to claim the net difference between actual and planned costs and allege that the difference was caused by the cumulative effect of events for which the employer is liable and which gives the contractor an entitlement to additional time and/or payment.

John Holland Pty Ltd v Hunter Valley Earthmoving Co Pty Ltd [2002] NSWSC 131 at [12]

The term “global claim” is used to describe a claim which does not readily permit the individual identification of each of its component parts.

Are global claims permissible?

A court will not deny a claim for damages on the ground that it is difficult to establish the exact amount of damages. However, a contractor will have to establish how the loss was caused.

Nauru Phosphate Royalties Trust v Matthew Hall Mechanical & Electrical Engineers Pty Ltd [1994] VicRp 67; [1994] 2 VR 386

The court expressed the view that it may be permissible to maintain a composite delay/disruption claim, that is a global claim, where it was impossible or impractical to identify a specific nexus between each of the alleged events and the particular delay/disruption caused.

John Holland Construction & Engineering Pty Ltd v Kvaerner RJ Brown Pty Ltd (1996) 8 VR 681

The decision in Nauru should not be taken as allowing for leniency.

In John Holland v Kvaerner, the court allowed a “total cost” claim where it was impracticable to disentangle that part of the loss which was attributable to each head of claim, and that this situation was not created by the conduct of the contractor.

Proving a global or total cost/time claim

If all the events causing loss have been demonstrated by the contractor as being the liability of the employer, then the courts do not always demand that the contractor demonstrates its additional costs/loss on a cause-by-cause basis.

Walter Lilly & Co Ltd v DMW Developments Ltd [2012] EWHC 1773 (TCC); [2012] BLR 503

The court emphasised that a mechanistic approach should not be adopted and that it is open to contractor’s to prove their claim with whatever evidence will satisfy the tribunal and the requisite standard of proof. There is no set way for contractors to prove their claim.

John Doyle Construction Ltd v Laing Management (Scotland) Ltd [2002] Scot CS110

“… However, if all the events are events for which [the employer] is legally responsible, it is unnecessary to insist on proof of which loss has been caused by each event”.

It is therefore essential to show that the contractor is not responsible for any of the alleged causes of loss. In reality, this is difficult.

Wunderlich Contracting Co v United States 351 F 2d 956; 173 Ct Cl 180 (1965) at 968; 199

The calculation of loss need not be exact, as long as the contractor has satisfied the burden of establishing the fundamental facts of liability, causation and resultant loss.

J Crosby & Sons Ltd v Portland Urban District Council (1967) 5 BLR 121 at 133, 136, 162; and

London Borough of Merton v Stanley Hugh Leach Ltd (1985) 32 BLR 51

J Crosby & Sons was followed by London Borough of Merton which involved a claim in which the employer argued that all the delay claimed was due to the contract administrator’s instructions. The court held that if loss and expense is incurred due to several reimbursable events which all contributed to the disruption costs incurred by the contractor, it was an artificial exercise to apportion those additional costs to each of the causative events.

However, the court did say:

“Implicit in the reasoning of Donaldson J was first that a rolled up award can only be made in a case where the loss or expense attributable to each head of claim cannot in reality be separated, and, secondly, that a rolled up award can only be made where apart from that practical impossibility the conditions which had to be satisfied before an award can be made have been satisfied in relation to each head of claim.

John Holland Construction & Engineering Pty Ltd v Kvaerner RJ Brown Pty Ltd (1996) 8VR 681 at [25]

“Where the loss is caused by a breach of contract, causation for the purposes of a claim for damages must be determined by the application of common sense to the logical principles of causation.”

Proof of causation

John Holland Construction & Engineering Pty Ltd v Kvaerner RJ Brown Pty Ltd (1996) 8VR 681 at [15]

It will be necessary for the contractor to demonstrate that the scope and cost of the work not affected by the alleged breach was reasonable.

Downer Connect Pty Ltd v McConnell Dowell Constructors (Aust) Pty Ltd [2008] VSC 77 at [34]

It will be necessary for the contractor to show that its tender price was reasonable.

Ipex ITG Pty Ltd v Melbourne Water Corporation (No3) [2006] VSC 83; Ipex ITG Ltd (receivers and managers appointed) v Melbourne Water Corporation [2012] VSCA 169;

The plaintiff claimed the difference between the cost of the labour and the quantity of labour agreed to be provided. However, the argument did not establish a true basis for the damages claimed in that there was no evidence that the work could have been carried out by the agreed resources had there been no breach. This was upheld by the appeal court.


Apportionment in relation to a global claim involves apportioning part of the global loss claimed to the causative events for which the employer can be held responsible.

John Doyle Construction Ltd v Laing Management (Scotland) Ltd [2004] Scot CS 141

This case concerned a global claim for concurrent delay. The court considered that evidence adduced during proceedings could possibly lead to a basis for an award of a lesser sum than was being claimed on a global basis. The court drew on the law in relation to contributory negligence and contribution as an analogy to apportionment of loss in relation to a global claim.

The court also considered that a contractor should be able to recover part of its loss and expense in a situation where the employer or architect was culpable and considered that the practical difficulties of carrying out an apportionment exercise should not prevent this.

Banabelle Electrical v New South Wales [2005] NSWSC 714

Where contractors globally combine claims for breach of contract with claims under the contract, the claim may fail because there may be different methods to assess entitlement and/or loss. The claim in Banabelle Electrical v New South Wales failed for this reason.

Obligation to prove causation

Mainteck Services Pty Ltd v Stein Heurtey SA [2014] NSWCA 184

The NSW Court of Appeal confirmed that Australian courts require proof of causation in the context of a global claim, but that courts recognise that a contractor may advance a global claim where it is impractical to disentangle the composite loss attributable to a series of causes and that situation was not brought about by the contractor.

The Court of Appeal formed the view that it is unlikely that a global claim will succeed if other causally significant events exist for which the defendant is not responsible. The Court of Appeal declined to follow John Doyle in which the court said it was possible in some cases to apportion loss between the causes.

John Holland Construction & Engineering Pty Ltd v Kvaerner RJ Brown Pty Ltd (1996) 8 VR 681

The court dealt with an application to strike out pleadings which succeeded. The claim was that the alleged breaches had caused all of the contractor’s losses calculated by reference to the difference between the tender estimate and the actual costs. The court said that the mere difficulty of estimating the damages flowing from a breach was not sufficient to deny relief to a plaintiff but said:

“But even in such a case, the plaintiff must identify the loss alleged to have been suffered and which cannot be quantified and how it is that this loss was caused by the breach.”

Having identified the claim as a global claim the court said:

“The logic of such a claim is this:

  1. the contractor might reasonably have expected to perform the work for a particular sum, usually the contract price;

  2. the proprietor committed breaches of contract;

  3. the actual reasonable cost of the work was a sum greater than the expected cost.

The logical consequence implicit in this is that the proprietor's breaches caused that extra cost or cost overrun. This implication is valid only so long as, and to the extent that, the three propositions are proved and a further unstated one is accepted; the proprietor's breaches represent the only causally significant factor responsible for the difference between the expected cost and the actual cost. In such a case the causal nexus is inferred rather than demonstrated… The unstated assumption underlying the inference may be further analysed. What is involved here is two things: first, the breaches of contract caused some extra cost; secondly, the proprietor's cost overrun is the extra cost… [The second aspect] involves an allegation that the breaches of contract were the material cause of all the contractor's cost overrun. This involves an assertion that, given that the breaches of contract caused some extra cost, they must have caused the whole of the extra cost because no other relevant cause was responsible for any part of it.”

Laing Management (Scotland) Ltd v John Doyle Construction Ltd [2004] BLR 295

It is accordingly clear that if a global claim is to succeed, whether it is a total claim or not, the contractor must eliminate from the causes of his loss and expense all matters that are not the responsibility of the employer.

Irene Henderson Ltd v Eddie Mair Ltd [2012] CSOH 66 at 97

This is equivalent to a “global claim” or “total cost claim” in building law; in such a case, the contractor must eliminate from the causes of his loss and expense all matters that are not the responsibility of the employer – John Doyle Construction Limited v Laing Management (Scotland) Limited 2004 SC 713 at [12] to [14]. In other words, if there is just one possible cause that is not the responsibility of the employers, the contractor's claim must fail. The onus rests on the pursuers to eliminate an alternative.

Quinn v Burch Bros (Builders) Ltd [1966] 2 QB 370; Bonnington Castings Ltd v Wardlaw [1956] AC 613

In a common law jurisdiction, the principles of causation are generally applied in an “all-or-nothing” manner. In the absence of any statutory obligation to apportion, common law courts have generally been inclined not to apportion damages between competing causes.

Adyard Abu Dhabi v SD Marine Services [2011] BLR 384; Walter Lilly & Co Ltd v Mackay [2012] BLR 503

In England and Wales, case law provides that apportionment is not an option in relation to concurrent causes of delay.

John Doyle Construciton Ltd v Laing Management (Scotland) Ltd [2004] Scot CS 141; Ipex ITG Pty Ltd v Melbourne Water Corporation (No3) [2006] VSC 83

John Doyle was cited by the Supreme Court of Victoria in Ipex, but was not in support of apportionment.

McGrath Corporation Pty Ltd v Global Construction Management (Qld) Pty Ltd [2011] QSC 178 at [129]-[132]

However, in McGrath Corporation v Global Construction Management (Qld), the Supreme Court of Queensland referred to the same passage of John Doyle with approval.

Astley v Austrust (1999) 197 CLR 1 at [85]

The Australian High Court said:

“Rarely do contracts apportion responsibility for damage on the basis of the respective fault of the parties. Commercial people in particular prefer the certainty of fixed rules to the vagueness of concepts such as “just and equitable”.