The SCL Delay and Disruption Protocol Explained: A Practical Guide to Proving Time and Cost Claims in Construction
Ask ten engineers on any delayed project to explain why the completion date slipped, and you will get ten different, equally sincere answers. Ask ten lawyers to translate those answers into a valid extension of time (EOT) or prolongation cost claim, and most of those claims will collapse the moment they are tested. The Society of Construction Law Delay and Disruption Protocol — universally known as the SCL Protocol — exists precisely to close that gap. It is the most widely cited methodology in the world for analysing construction delay and disruption, referenced by tribunals, adjudicators, and forensic experts from London to Dubai to Kuala Lumpur. In our experience advising contractors and employers on FIDIC-based and domestically governed construction contracts, the single biggest predictor of whether a time or money claim survives scrutiny is not the strength of the underlying facts — it is whether the claim was built on a defensible, Protocol-consistent method from the outset. This article explains what the SCL Protocol actually says, where it sits alongside FIDIC and other international standards, how it interacts with domestic contracting practice in jurisdictions such as Iran, and how Claimetrix applies it in live disputes.
1. What the SCL Protocol Is, and Why It Decides Cases Long Before Any Tribunal Convenes
1.1 A short history: from the 2002 Protocol to the 2017 Second Edition
The Society of Construction Law (SCL), a UK-based professional body dedicated to the study and application of construction law, first published the Delay and Disruption Protocol in October 2002. The first edition was a response to a genuine industry problem: delay and disruption claims were being prepared and assessed using wildly inconsistent methods, producing inconsistent — and often indefensible — results. A limited update, Rider 1, followed in 2015 to address the misuse of Time Impact Analysis in practice. In February 2017, the SCL published the Second Edition, which superseded both earlier documents and remains the current, authoritative version referred to throughout this article. The Second Edition expanded the guidance from a single preferred delay-analysis method to six recognised methodologies, modernised the treatment of concurrent delay in light of English case law, and restructured the guidance around twenty-two Core Principles — the backbone discussed in Section 2 below.
1.2 What the Protocol is not: guidance, not law, not a contract
A recurring misunderstanding — even among experienced project engineers — is treating the SCL Protocol as if it were binding law or an automatically incorporated contract term. It is neither. The Protocol itself states plainly that it does not have contractual force unless the parties expressly incorporate it, in whole or in part, into their contract. Its authority instead comes from something more durable: it is the closest thing the international construction industry has to a consensus statement of good practice, drafted by a working party of barristers, solicitors, quantity surveyors, and delay experts, and refined through nearly two decades of real dispute experience. Because of that consensus status, English courts and international tribunals have repeatedly referred to the Protocol's Core Principles when reasoning about concurrent delay, the prevention principle, and the proper basis for extending time — most notably in the concurrent-delay jurisprudence that runs from Walter Lilly & Co Ltd v Mackay [2012] EWHC 1773 (TCC) through to North Midland Building Ltd v Cyden Homes Ltd [2018] EWCA Civ 1744, discussed further in Section 2.4. In practical terms, this means a delay analysis that departs from Protocol methodology without good reason starts every dispute at a credibility disadvantage — even where it is not contractually mandated.
1.3 The recurring pattern we see in practice
Across the delay and disruption files handled by our team on EPC, infrastructure, and industrial projects, the same structural weaknesses appear again and again — and almost none of them are about the underlying facts of the delay. They are about how the claim was built. The chart below summarises the root causes we most frequently identify when a time or cost claim under-performs at expert review, adjudication, or arbitration.
Source: internal Claimetrix review of delay and disruption files across infrastructure and industrial projects. Figures are indicative and issues frequently co-occur within a single claim.
1.4 Why engineers and lawyers read the same programme differently
A planning engineer looking at an updated Primavera P6 file asks: which activities slipped, and why? A construction lawyer looking at the same file asks: whose risk was that, under which clause, and was notice given in time? Both questions are legitimate, and both are necessary — but neither, on its own, produces a claim that survives scrutiny. The SCL Protocol's real contribution is a shared vocabulary that lets both professions interrogate the same programme data and reach a joint, defensible conclusion. This is precisely why the Protocol structures its guidance around Core Principles rather than a rigid set of calculation rules: it is written to be read by both audiences at once. Later sections of this article are deliberately organised the same way — the technical mechanics of each methodology are explained alongside the legal question each is meant to answer, since in our experience a report that only satisfies one of the two audiences rarely survives contact with the other side's expert.
| Programme fact | Engineering question | Legal question |
|---|---|---|
| An activity finishes 14 days late | Was the activity on the critical path when the delay occurred? | Was the cause of the delay an employer risk, a contractor risk, or a neutral event under the contract? |
| The overall completion date slips by 30 days | Which contemporaneous programme update first showed the slippage, and through which path? | Was notice given within the contractual period, and does the delay meet the EOT entitlement test? |
| Two delay events overlap in time | Do both events independently drive the critical path during the overlap (true concurrency), or does only one? | Does the contract's concurrency clause follow the Protocol default, or displace it? |
2. The Twenty-Two Core Principles: What the Protocol Actually Says
The heart of the Second Edition is a set of twenty-two Core Principles, grouped below by subject area. They are not drafted as strict rules but as a coherent, internally consistent framework for how time and money claims should be identified, analysed, and valued.
| Subject area | Core Principles | What it governs |
|---|---|---|
| Programme & contemporaneous analysis | 1, 4, 11 | Maintaining a properly logic-linked baseline and regularly updated programme; analysing delay as it happens rather than adopting a "wait-and-see" approach; the diminishing reliability of analysis performed long after the delay event. |
| Extension of time (EOT) | 2, 3, 5, 6, 7 | The purpose of EOT (relieving the contractor from liquidated damages, not a reward); the entitlement test; the contractual notice and procedural steps; the effect of granted EOT; and incremental review as impacts unfold. |
| Float & criticality | 8, 9 | How float is identified on the programme and, absent an express contractual term to the contrary, how it is treated as a shared project resource rather than owned exclusively by either party. |
| Concurrent delay | 10, 14 | The effect of true concurrent delay on entitlement to time (Principle 10) and separately on entitlement to prolongation compensation (Principle 14) — two distinct questions the Protocol deliberately does not conflate. |
| Compensation, mitigation & acceleration | 12, 13, 15, 16, 19, 20, 21, 22 | The link (or lack of it) between an EOT and a right to money; early completion and its effect on compensation; the duty to mitigate; constructive and directed acceleration; valuation of variations; the basis, relevance of tender allowances, and time period for calculating prolongation costs. |
| Global claims & disruption | 17, 18 | The Protocol's cautious approach to composite/global claims that do not link cause to effect, and the separate treatment of disruption (productivity loss) as distinct from delay to completion. |
2.1 Extension of time: purpose, test, and procedure
Under the Protocol, an EOT exists for one purpose only: to relieve the contractor of liability for liquidated damages for the period of delay caused by an employer risk event, and to establish a new contractual completion date. It is not compensation, and it is not a discretionary grace period. The entitlement test asks a single, focused question: did the relevant employer-risk event reduce the contractor's ability to complete by the then-current contract completion date? The Protocol also insists that EOT assessment follow the contract's own procedural machinery — notices, particulars, and time bars — and that, where full impact cannot yet be measured, awards be made incrementally and revised upward (but not normally downward) as actual effects become known. This is precisely the mechanism embedded in FIDIC's Sub-Clause 8.5 (2017 Red Book) / Sub-Clause 8.4 (1999 Red Book) and the corresponding claims procedure in Sub-Clause 20.2, where a contractor that fails to give notice within the contractual period risks losing an otherwise valid entitlement altogether — a strict, condition-precedent approach upheld in English and international jurisprudence.
2.2 Float: who owns the cushion?
Float — the amount of time an activity can be delayed without affecting the completion date — is one of the most contested resources on any programme. The Protocol's position, reflected in Core Principles 8 and 9, is that float belongs to the project, not to either party, unless the contract expressly says otherwise. In practice this means an EOT is only justified once an employer-risk event has consumed all the float on the affected path and is genuinely threatening the completion date — not merely eating into a contingency the contractor built into its own programme. This single principle is frequently the deciding factor in disputes where a contractor claims an EOT for a delay that, on the programme, never actually reached the critical path.
2.3 Concurrent delay: the single most litigated principle
Concurrent delay arises where an employer-risk event and a contractor-risk event each independently and simultaneously cause critical delay to completion. The Protocol's Core Principle 10 states that, where true concurrent delay is established, the contractor's own concurrent delay should not reduce the extension of time otherwise due from the employer-risk event. Core Principle 14 then draws the crucial distinction for money: while the contractor may still receive the time, it should generally not receive prolongation compensation for the concurrent period, since it would have incurred those costs regardless of the employer's event. This split — time without money during genuine concurrency — is one of the most frequently misunderstood (and most frequently litigated) points in international construction disputes. English case law has both applied and, through freedom of contract, permitted parties to contract around this default position: Walter Lilly & Co Ltd v Mackay [2012] EWHC 1773 (TCC) confirmed the "but-for" test for true concurrency and awarded the contractor its EOT despite concurrent contractor delay, while North Midland Building Ltd v Cyden Homes Ltd [2018] EWCA Civ 1744 confirmed that parties are free to draft a clause expressly excluding EOT relief during concurrent delay — a reminder that the Protocol is a default position, displaceable by clear contract drafting.
| Scenario | Default SCL Protocol position | Common contractual variation |
|---|---|---|
| True concurrent delay (both events independently critical) | EOT granted in full; prolongation cost apportioned or excluded for the concurrent period | Some bespoke amendments (e.g., following Cyden Homes-style drafting) exclude EOT entirely during concurrency, shifting full time risk to the contractor |
| Sequential, not truly concurrent delay | Ordinary "but-for" causation analysis applies; no special concurrency treatment | Generally unchanged, though poorly drafted clauses sometimes conflate sequential and true concurrency |
| Pacing (contractor slows non-critical work in response to an employer delay) | Not treated as culpable contractor delay if reasonably and contemporaneously evidenced | Frequently disputed where contemporaneous records of the pacing decision are absent |
2.4 Global claims: why the Protocol — and most tribunals — discourage them
A global (or composite) claim asserts a single lump-sum entitlement for an overall loss without linking each individual causative event to its specific time or cost effect. Core Principle 17 discourages this practice, favouring claims that establish cause and effect event by event, even where that requires more analytical effort. While some courts have softened a once-absolute hostility to global claims where individual linkage is genuinely impracticable, the Protocol's guidance — and our own experience defending and attacking such claims — is unambiguous: a claim that cannot show which specific event caused which specific day of delay or dollar of loss is inherently vulnerable to a "knock-out" defence, in which the responding party need only prove that some part of the alleged cause was outside the employer's responsibility to defeat the entire claim.
2.5 Disruption vs delay: a distinction engineers often miss
Delay affects the completion date; disruption affects productivity — the efficiency with which resources perform work, whether or not that work sits on the critical path. A crew forced to work out of sequence, in cramped conditions, or with repeated stop-start interruptions may suffer real, compensable productivity loss even on a project that finishes on time. Core Principle 18 requires disruption to be proven on its own terms, separately from any delay analysis, and the Protocol's preferred method — where records permit — is the measured mile approach: comparing labour or plant productivity during an unimpacted reference period against productivity during the disrupted period, on comparable scopes of work. Where a genuine measured mile is unavailable, the Protocol recognises alternative methods (industry studies, earned value, and other analytical techniques) but consistently ranks them below a well-evidenced measured mile in terms of reliability.
2.6 Mitigation and acceleration: the contractor's duty, and the employer's alternative
Core Principle 15 confirms that a contractor claiming an EOT remains under an ordinary duty to mitigate the effects of employer-risk delay — though critically, the Protocol does not require the contractor to take extraordinary or unbudgeted measures beyond what a reasonably prudent contractor would do in the circumstances. This is distinct from acceleration (Core Principle 16), which arises where either party takes deliberate steps to recover lost time rather than simply absorb it as an EOT. The Protocol distinguishes two forms: directed acceleration, where the employer instructs the contractor to accelerate — usually against additional payment — and constructive acceleration, where the employer wrongly withholds an EOT that was genuinely due, and the contractor accelerates at its own cost to avoid exposure to liquidated damages it should never have faced. Constructive acceleration claims are notoriously difficult to prove, precisely because they require the same rigorous, event-by-event delay analysis discussed throughout this article — first to establish that the EOT should have been granted, and only then to quantify the cost of accelerating around the employer's refusal.
- A logic-linked baseline programme, reviewed and accepted early Without an accepted baseline, every later analysis has to first fight over what the "as-planned" position even was.
- Contemporaneous, periodic programme updates covering the disputed period Gaps in the update history are the single most common reason a chosen method has to be abandoned mid-analysis.
- Event-by-event causation, not a single narrative summary Each day of delay claimed should trace back to a specific, dated, evidenced cause.
- Explicit treatment of concurrency, not silence A report that never mentions concurrent contractor-side events invites the other side to raise it first, on its own terms.
- A clear link from the technical finding to the specific contract clause relied upon A finding that "the critical path moved by 21 days" is not yet a claim; it becomes one only once tied to the EOT and notice provisions actually in the contract.
The five items above form the checklist our team applies to every delay report before it leaves the office — whether we are preparing it for a client or reviewing an opposing expert's report for a weakness to challenge.
3. The Six Delay Analysis Methodologies
Unlike its predecessor, the Second Edition does not prescribe a single "correct" method. Instead, it sets out six recognised delay-analysis methodologies and directs practitioners to select the one best suited to the contract terms, the purpose of the analysis, and — critically — the quality and completeness of the available programme records.
| Method | Perspective | How it works | Best suited to / key limitation |
|---|---|---|---|
| Impacted As-Planned | Prospective | Inserts delay events into the original baseline programme to model their theoretical effect on completion | Useful early, low-data situations; ignores actual progress and re-sequencing, so least persuasive after the fact |
| Time Impact Analysis (TIA) | Prospective, contemporaneous | Inserts a fragnet for the delay event into the contemporaneous updated programme at the time the event occurred, to show its live impact on the then-current completion date | The Protocol's recommended method during project execution, provided reliable periodic updates exist |
| Time Slice / Snapshot Windows | Retrospective | Divides the project into windows using successive contemporaneous programme updates and traces the actual critical path through each window | Strong where good-quality periodic updates exist throughout the project |
| As-Planned vs As-Built Windows | Retrospective | Compares planned and as-built logic within defined windows to identify critical delay in each period | Effective where updates are incomplete but as-built records are reliable |
| Retrospective Longest Path | Retrospective | Identifies the longest continuous path of as-built activities working backward from actual completion | Useful where updated programmes are poor or absent, relying instead on robust as-built data |
| Collapsed As-Built (Modified As-Built) | Retrospective, "but-for" | Removes ("collapses") delay events from the as-built programme to model the completion date that would have resulted without them | Powerful for isolating a specific event's effect, but highly sensitive to logic assumptions and data quality |
4. Available Solutions: International Standards, Domestic Practice, and the Optimal Path Forward
The SCL Protocol does not exist in isolation. Employers, contractors, and their advisers navigating a live delay dispute typically draw on three layers of guidance: established international standards and institutions, the domestic contracting and dispute-resolution framework that actually governs the project, and — where the first two leave gaps — a bespoke, blended methodology tailored to the specific contract and evidentiary record.
4.1 International solutions
| Standard / body | Issuing organisation | Focus | Relationship to the SCL Protocol |
|---|---|---|---|
| SCL Delay & Disruption Protocol | Society of Construction Law (UK) | Comprehensive guidance on delay, disruption, EOT, and compensation | The primary reference framework discussed throughout this article |
| AACE RP 29R-03 Forensic Schedule Analysis | AACE International | A more granular technical taxonomy of delay-analysis methods, widely used by US-trained forensic schedulers | Substantially overlapping methodology; often used alongside the Protocol to cross-check method selection |
| RICS "Extensions of Time" guidance (the "Black Book") | Royal Institution of Chartered Surveyors | Practical guidance for quantity surveyors assessing EOT entitlement | A quantum-focused companion to the Protocol's more technical delay methodology |
| FIDIC Conditions of Contract (Sub-Clauses 8.5 & 20.2, 2017 Red/Yellow/Silver Books) | FIDIC | The contractual EOT and claims-notice machinery most international projects actually operate under | The Protocol supplies the analytical method; FIDIC supplies the binding procedural and substantive rules the analysis must serve |
| IBA Rules on the Taking of Evidence, Art. 5 | International Bar Association | Governs the role, independence, and duties of party-appointed delay experts in international arbitration | Frames how a Protocol-based delay report should be prepared and presented as expert evidence |
| Dispute Adjudication/Avoidance Boards (DAB/DAAB) | FIDIC-administered | Standing, project-embedded panels for real-time resolution of delay and other disputes | A procedural forum in which Protocol-consistent delay analysis is regularly tested and relied upon |
4.2 Domestic and regional practice
In many jurisdictions where our team operates — Iran and the wider MENA region among them — domestic general conditions of contract and standard forms were drafted before internationally recognised delay-analysis methodologies became standard practice, and typically remain silent on which method should be used to assess EOT entitlement. Iran's own General Conditions of Contract (Publication No. 4311) is a case in point: it establishes the contractual right to an extension of time and the broad categories of excusable delay, but it does not mandate — or even mention — a specific analytical methodology such as Time Impact Analysis or Windows Analysis. In the absence of such a requirement, outcomes vary considerably depending on the training and inclination of whichever expert or adjudicator ultimately reviews the claim, and court-appointed technical experts under Article 257 of the Civil Procedure Code, however competent in general civil-works valuation, are not always trained in forensic schedule analysis specifically.
| Gap | Practical consequence | Common remedy |
|---|---|---|
| No mandated delay-analysis method in domestic general conditions | Inconsistent outcomes across similar disputes; unpredictability for both employers and contractors | Voluntary adoption of Protocol-consistent methodology (typically TIA or Windows Analysis) in the claim submission itself |
| Court/tribunal-appointed experts without specialist forensic scheduling training | Findings that may not withstand technical challenge from a party-appointed delay expert | Independent party-appointed expert review submitted alongside, or in response to, the official expert opinion |
| Limited institutional recognition of "delay analyst" as a distinct discipline | Quality of analysis depends heavily on individual track record rather than a recognised qualification | Reliance on internationally credentialed practitioners (e.g., AACE PSP/CFCC holders) and demonstrable case history |
| Short, document-limited site visits by officially appointed experts | Conclusions reached without full engagement with the updated programme history | Pre-assembly of an indexed, cross-referenced evidence bundle before the expert visit |
4.3 Claimetrix's recommended, blended approach
Neither the international standards nor domestic practice, taken alone, resolves the problem. Our approach is to treat the SCL Protocol as the analytical backbone of every delay or disruption claim, while adapting its presentation to the procedural and evidentiary expectations of whichever domestic or contractual forum will actually decide the dispute. In practice, this means running Protocol-consistent Time Impact Analysis or Windows Analysis wherever the underlying programme data supports it, but writing the resulting report in a form that a domestic court-appointed expert, an arbitral tribunal, or a FIDIC Dispute Board can each independently follow and test — with every finding traced back to a specific contract clause, a specific programme update, and a specific contemporaneous record.
| Stage | When | Action | Effect |
|---|---|---|---|
| Diagnose | During project execution | Periodic review of the updated programme to flag emerging critical-path deviations and open a contemporaneous record for each candidate delay event | Shrinks the gap between when a delay occurs and when it is formally documented |
| Model | Once an event's significance is confirmed, or ahead of formal proceedings | Selection and execution of the SCL Protocol method best matched to the available records, run by a team combining planning/scheduling and contract-law expertise | Produces an analysis that is simultaneously technically rigorous and legally defensible |
| Defend | At expert conferral, adjudication, or arbitration | Direct participation of the delay analyst in hearings, responding in real time to challenges from the opposing expert or tribunal | Materially improves the rate at which the analysis survives cross-examination and expert challenge |
5. Claimetrix Services and Track Record in SCL Protocol-Based Delay and Disruption Analysis
Claimetrix combines dedicated planning and scheduling specialists with construction-contract lawyers within a single delivery team — precisely the pairing the SCL Protocol assumes but which is rarely found together in-house on either the employer or contractor side. The services below are the direct output of that combination.
| Service | Description | Deliverable |
|---|---|---|
| Preliminary entitlement assessment | Rapid review of the contract, programme, and correspondence to establish whether a credible basis for an EOT or disruption claim exists | Entitlement assessment memorandum with preliminary event classification |
| Full SCL Protocol-based delay analysis | Execution of the delay-analysis method best matched to available records (TIA, Windows Analysis, Collapsed As-Built, and others), by a combined planning/legal team | Delay expert report with supporting programme model |
| Disruption / productivity loss analysis | Measured-mile and alternative productivity-loss analysis to quantify disruption independently of any completion-date effect | Disruption report with productivity baseline and loss calculation |
| Review and challenge of opposing/official expert reports | Independent reconstruction of the programme model to identify technical weaknesses in a court-appointed or opposing expert's delay opinion | Technical-legal critique report and formal objection submission |
| Expert presence at hearings, conferral, and arbitration | Direct attendance of the Claimetrix delay analyst to defend the analysis and respond to opposing experts or tribunal questions, including joint expert conferral ("hot-tubbing") | Hearing minutes and technical defence notes |
| Real-time delay monitoring and documentation systems | Design and implementation of periodic programme-monitoring procedures and contemporaneous delay-event documentation, before disputes arise | Monitoring procedure, standard record templates, and technical team training |
| Specialist training | Structured courses and workshops on delay analysis, the SCL Protocol, and construction claims management for engineering and legal teams | Training programme with applied case-study materials |
5.1 Representative experience
- Upgrading multiple in-progress delay submissions from narrative descriptions to fully modelled Time Impact Analyses, with a direct, measurable improvement in employer acceptance rates.
- Identifying and substantiating true concurrent delay on an industrial project where the employer's initial position had attributed an entire overlapping delay period to the contractor alone.
- Attending official expert-panel site visits to respond directly to technical objections raised against the submitted programme model.
- Designing and deploying a periodic programme-monitoring procedure for an industrial employer, aimed at flagging critical-path deviation before it hardens into a formal dispute.
Before the other side's expert opinion becomes the record, complete your team
Every delay or disruption claim that enters expert review, adjudication, or arbitration without an independent, Protocol-consistent analysis behind it starts one step behind. Claimetrix is ready to review your contract, programme, and correspondence, and deliver a preliminary entitlement assessment before your next notice deadline.
Request a Case Review6. Frequently Asked Questions
What exactly is the SCL Delay and Disruption Protocol?
It is a guidance document, first published in 2002 and now in its Second Edition (2017), produced by the UK Society of Construction Law to set out good practice for analysing and assessing delay and disruption in construction projects — covering extension-of-time entitlement, concurrent delay, disruption, global claims, and six recognised delay-analysis methodologies.
Is the SCL Protocol legally binding on my contract?
No, not unless the parties expressly incorporate it into the contract. It is not law and not a standard-form contract. Its influence instead comes from its status as a widely accepted statement of good practice, which courts, arbitral tribunals, and forensic experts routinely reference when assessing the credibility of a delay analysis.
Which delay-analysis method should I use for my project?
The Second Edition deliberately does not name a single preferred method. The right choice depends on the contract's requirements, the purpose of the analysis (prospective vs retrospective), and — most importantly — the completeness and reliability of the project's baseline and periodically updated programmes. Time Impact Analysis is generally recommended for prospective, real-time assessment where reliable contemporaneous updates exist.
What is "true" concurrent delay, and does it destroy my extension-of-time claim?
True concurrent delay exists only where an employer-risk event and a contractor-risk event each independently and simultaneously cause critical delay to completion. Under the Protocol's default position, genuine concurrent delay does not reduce the extension of time otherwise due — though it will usually limit or exclude the contractor's entitlement to prolongation costs for that same period. Some contracts expressly override this default, so the governing contract clause must always be checked first.
What is the difference between a delay claim and a disruption claim?
A delay claim concerns the effect of an event on the completion date, via the critical path. A disruption claim concerns lost productivity or efficiency in performing the work, which can occur even on activities with float or on a project that ultimately finishes on time. The two are analysed separately, using different methods — delay analysis for the former, and typically a measured-mile productivity comparison for the latter.
Why does the Protocol discourage "global claims"?
Because a global claim seeks a single lump-sum entitlement without linking each specific causative event to its specific time or cost effect, it is inherently exposed: a responding party can often defeat the entire claim simply by showing that some part of the alleged cause falls outside its responsibility. The Protocol strongly favours claims that establish cause-and-effect on an event-by-event basis, even where more analytical effort is required.
Who owns float on the programme — the contractor or the employer?
Under the Protocol's default position, float belongs to the project as a shared resource, not to either party individually, unless the contract expressly states otherwise. An extension of time is generally only justified once an employer-risk event has consumed the available float on the affected path and is genuinely threatening the completion date.
Does the SCL Protocol apply if my contract is FIDIC-based?
Yes, in practice it usually does, though indirectly. FIDIC's Sub-Clauses 8.5 and 20.2 (2017 editions) set out the binding notice, particulars, and procedural requirements for an EOT claim, but they do not prescribe a delay-analysis methodology. The SCL Protocol is the standard most commonly used to satisfy that analytical gap on FIDIC-governed projects internationally.
What happens where domestic contract conditions, such as Iran's General Conditions of Contract, are silent on delay-analysis methodology?
In that gap, outcomes vary by whichever expert or adjudicator reviews the claim, since there is no mandated method to anchor the analysis. The practical remedy is to voluntarily present the claim using a Protocol-consistent methodology (typically Time Impact Analysis or Windows Analysis), giving the reviewing expert or tribunal a recognised, internationally tested framework to test the analysis against, rather than leaving the assessment to an unstructured narrative review.
Can an employer use the SCL Protocol too, or is it only a contractor's tool?
Both sides use it, and should. Just as a contractor needs a Protocol-consistent analysis to substantiate an EOT claim, an employer needs an equally rigorous independent analysis to test that claim — rather than relying solely on an officially appointed expert's opinion, which may not be built on forensic schedule-analysis training specifically.
When should a delay analyst be engaged — before or after a dispute arises?
Ideally, before a formal dispute crystallises, through periodic programme monitoring and contemporaneous documentation of delay events as they occur. An analysis built on records created at the time of the event carries far greater evidentiary weight than one reconstructed months later. Engaging an analyst only once proceedings are imminent is still valuable, but it is the second-best option.
Is planning software such as Primavera P6 enough to prepare a delay claim on its own?
No. Scheduling software is a modelling tool, not a substitute for the legal analysis of causation, entitlement, and contractual procedure. The software's output must be interpreted and connected to the contract's specific terms and notice requirements by someone trained in both disciplines; otherwise, a technically accurate model can produce a report with no legal traction whatsoever.
What is the difference between mitigation and acceleration under the Protocol?
Mitigation is the contractor's ordinary duty to take reasonable steps to limit the effect of an employer-risk delay — it does not require extraordinary or unbudgeted measures. Acceleration is a separate, deliberate effort to recover lost time rather than absorb it as an EOT, and comes in two forms: directed acceleration (instructed and usually paid for by the employer) and constructive acceleration (undertaken by the contractor at its own cost because the employer wrongly withheld an EOT that was actually due).
Can a contractor recover the cost of accelerating the works?
Yes, in two situations. Directed acceleration is normally compensated under the instruction that ordered it. Constructive acceleration can also be recovered, but only where the contractor first proves that an EOT was genuinely due and wrongly refused or not granted in time — which means a constructive acceleration claim depends entirely on the same rigorous delay analysis described throughout this article.
References
- Society of Construction Law, Delay and Disruption Protocol (2nd Edition, February 2017) — SCL.
- AACE International, Recommended Practice No. 29R-03, Forensic Schedule Analysis — AACE International.
- RICS, Extensions of Time — RICS Practice Information, UK 1st Edition, November 2014 — RICS.
- FIDIC Conditions of Contract (2017 Red/Yellow/Silver Books) — Sub-Clauses 8.5 and 20.2 — FIDIC.
- IBA Rules on the Taking of Evidence in International Arbitration (2020) — Article 5, Party-Appointed Experts — International Bar Association.
- Walter Lilly & Co Ltd v Mackay [2012] EWHC 1773 (TCC).
- North Midland Building Ltd v Cyden Homes Ltd [2018] EWCA Civ 1744.
- General Conditions of Contract, Publication No. 4311, Plan and Budget Organization of Iran.
- Civil Procedure Code of Iran — Article 257 (court-appointed technical experts).
- Claimetrix — Construction Claims and Delay Analysis Services.
Disclaimer: This article is for general analytical and educational purposes and does not constitute legal or technical advice for any specific project or dispute. Standards, editions, and case law referenced above may be superseded or updated; the current, applicable version should always be verified before reliance in any live matter.
