Delay & Disruption Analysis

Section 1

Purpose

Note on JCT editions: JCT has published the 2024 Edition. This guidance cites JCT SBC/Q 2016 clause references; the commercial and payment mechanisms are substantively unchanged in the 2024 edition, but specific clause references should be verified against the contract edition in use on any given project.

Delay and Disruption Analysis is the technical and financial assessment of the time and cost impacts of employer-caused or force majeure events on the contractor's programme and resources. It underpins both extension of time (EOT) claims (for delay) and loss and expense/prolongation claims (for financial impact). The analysis must be methodologically sound, based on contemporaneous records, and clearly distinguish between employer-caused delay and contractor-caused delay (or concurrent delay).

RICS Ascertaining Loss and Expense (2nd ed., July 2024) and RICS Extensions of Time (1st edition, November 2014, effective 10 February 2015; reissued July 2024 as RICS practice information) establish the professional framework for delay and disruption analysis in England & Wales. The Society of Construction Law (SCL) Delay and Disruption Protocol (2nd ed., 2017) is the industry-recognised methodology guide — adjudicators, arbitrators, and courts routinely refer to it when assessing delay claims.

The distinction between delay (impact on programme, recoverable as EOT) and disruption (impact on productivity, recoverable as loss and expense) is critical: they are separate entitlements with different methodologies and different evidence requirements. A contractor who conflates the two, or who claims disruption without a valid EOT, will have both elements challenged.

Section 2

Key Principles

RICS Extensions of Time (1st edition, November 2014, effective 10 February 2015; reissued July 2024 as RICS practice information): Relevant Events (JCT Clause 2.29) entitle the contractor to EOT; the extension is to the Completion Date, not to the programme; concurrent delay (both parties at fault) is not generally compensable in England & Wales (Malmaison approach).
RICS Ascertaining loss and expense (RICS practice information, UK, 2nd edition, July 2024): prolongation costs require (i) a Relevant Matter — an independent money entitlement, not conditional on an extension of time, since the list of Relevant Matters is not the same as the list of Relevant Events; (ii) compliance with the contractual notice and information requirements; (iii) actual loss — time-based or resource-based; (iv) a causal link; (v) substantiation. Emden formula for head office overhead: (H/100 × C/P) × T.
SCL Delay and Disruption Protocol (2nd ed., 2017): recommends contemporary delay analysis (Prospective/Time Impact Analysis) over retrospective methods where possible; critical path analysis (CPA) should be based on the accepted baseline programme.
Concurrent delay: where both employer and contractor delays are concurrent (both occurring simultaneously), English law generally does not award EOT or L&E for the employer's delay element (Henry Boot v Malmaison Hotel [1999]).
Disruption: separate from delay — disruption is the impact on productivity caused by an employer event (e.g. repeated late instructions, restricted access); quantified using a measured mile approach (comparison of actual productivity vs planned/undisrupted productivity).
Prevention principle: if the employer causes delay without an available EOT mechanism, the time for completion becomes 'at large' and LADs are unenforceable (Multiplex v Honeywell [2007]).

Section 3

Practical Application

Step 1

Establish the baseline programme: the accepted/agreed contract programme (with a valid critical path); this is the benchmark against which delay events are measured; the baseline programme must be the contractor's approved programme, not their tender programme.

Step 2

Identify delay events: map each delay event to a Relevant Event (JCT) or Compensation Event (NEC4); confirm the event is within the employer's risk sphere; document the cause, start and end dates, and the affected activities.

Step 3

Apply the appropriate delay analysis methodology: Time Impact Analysis (prospective — most reliable); As-Built vs As-Planned (retrospective — useful for overview); Windows Analysis (hybrid — good for complex concurrent delay scenarios). Use the SCL Protocol guidance to select the most appropriate method for the complexity of the project.

Step 4

Assess concurrent delay: identify all contractor-caused delays occurring in the same period as the employer-caused delay event; document the concurrent periods; apply the Malmaison principle (neither party compensated for the concurrent period in English law).

Step 5

Quantify the prolongation costs for the EOT period: assemble time-related preliminaries records (site establishment costs, supervision, plant); calculate the time-related cost per week; multiply by the agreed EOT period.

Step 6

For disruption claims: calculate the planned productivity rate from the baseline programme; calculate the actual productivity rate from contemporaneous records; the difference is the measured productivity loss; multiply by the labour cost to calculate the disruption cost.

Step 7

Prepare the delay and disruption analysis report: include the baseline programme; delay event narrative; delay analysis methodology and results; EOT entitlement conclusion; prolongation/disruption quantum; supporting evidence cross-referenced.

Section 4

Common Mistakes to Avoid

Treating an extension of time as a precondition to loss and expense, or assuming that an extension of time automatically carries a money entitlement. Both are wrong. Relevant Matters (money) and Relevant Events (time) are separate lists: an EOT granted for a Relevant Event that is not a Relevant Matter gives no loss and expense, and a Relevant Matter can found a loss and expense claim — for example disruption without critical delay — with no EOT at all. The real gateways are a Relevant Matter, compliance with the contractual notice provisions, causation and substantiation.
Using the tender programme (not the accepted contract programme) as the baseline — the tender programme is often the contractor's wishful thinking; the baseline must be the accepted programme that reflects the actual contract period.
Failing to identify concurrent delay — ignoring concurrency exposes the employer to payment of prolongation costs for periods where the contractor's own delay was equally operative.
Relying on global claims (claiming a total cost without a causal link to specific events) — global claims are inherently weak and are routinely rejected by adjudicators and courts unless all the events can be linked to a single cause.
Conflating delay (programme impact) with disruption (productivity impact) — they require separate analysis and separate evidence; combining them in a single undifferentiated claim weakens both.

Section 5

APC Competency & Quick Reference

Conflict Avoidance, Management and Dispute Resolution Procedures Level 3 — delay analysis methodology, EOT, prolongation, disruption
Contract Practice Level 3 — Relevant Events, Relevant Matters, concurrent delay, prevention principle

What is the Malmaison approach to concurrent delay and how does it apply in English law?

The Malmaison approach (Henry Boot v Malmaison Hotel [1999]) provides that where the contractor is entitled to an EOT for a Relevant Event and the contractor's own delay is concurrent, the contractor is entitled to the EOT but not to loss and expense for the concurrent period. This is the prevailing English law approach. It differs from the US approach (which may grant EOT for both events) and the Scottish approach.

What is the measured mile approach to disruption analysis?

The measured mile compares the contractor's productivity during a disrupted period against their productivity during an undisrupted period (the 'measured mile'). For example: if the contractor installed 50 bricks/hour in the undisrupted period but only 35 bricks/hour in the disrupted period, the 15 bricks/hour shortfall is the disruption loss. The measured mile is only valid if the two periods are genuinely comparable (same trade, similar conditions, similar specification).

What is the Emden formula and when should it be used for head office overhead recovery?

Emden formula: (H/100 × C/P) × T. H = head office overhead %; C = contract sum; P = contract period (weeks); T = extension period (weeks). It is used when actual head office overhead costs attributable to the project cannot be directly evidenced. The SCL Protocol and RICS Ascertaining Loss and Expense (2nd ed.) recommend using actual cost where possible; Emden is appropriate only where actual cost cannot be established. Hudson's formula (using tendered overhead %) is an alternative.

Section 6

Dispute & Claims Checklist

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Task

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Baseline programme (accepted contract programme) identified and verified

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Delay events mapped to Relevant Events / Compensation Events

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Delay analysis methodology selected per SCL Protocol guidance

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Concurrent delay periods identified and Malmaison principle applied

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Prolongation costs assessed: time-based prelims for EOT period

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Disruption costs assessed using measured mile or alternative method

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Delay and disruption analysis report prepared with full evidence cross-referencing

Section 7

CPD Learning Outcomes

Apply delay analysis methodologies from the SCL Delay and Disruption Protocol (2nd ed., 2017) to identify, programme, and quantify the impact of employer-caused delay events on the contractor's Completion Date.
Apply the Malmaison concurrent delay principle and distinguish between delay (EOT entitlement) and disruption (productivity loss), using the measured mile or comparable method for disruption quantification.
Calculate prolongation costs using actual cost or the Emden formula, establishing a clear causal link between the EOT-entitling event and each element of the claimed prolongation cost.

Section 8