Concurrent Delay — Attribution and Entitlement

Understanding Concurrent Delay in Construction Projects

Concurrent delay is one of the most complex and debated concepts in construction law and delay analysis. In simple terms, concurrent delay occurs when two or more delay events overlap in time, with at least one attributable to the employer and another to the contractor.

Despite its frequent occurrence in construction projects, concurrent delay is often misunderstood, oversimplified, or incorrectly applied. The correct assessment of concurrent delay requires careful analysis of causation, contractual provisions, and applicable legal principles.

The Core Problem with Concurrent Delay

The challenge with concurrent delay lies in identifying causation and entitlement where multiple delay events interact.

The “classic” scenario of concurrent delay involves:

• Two independent delay events
• Occurring at the same time
• Each delaying project completion by the same duration
• One event attributable to the employer and one to the contractor

This is often referred to as true concurrent delay.

However, in practice, concurrent delay is rarely this clear-cut. More commonly:

• Delay events only partially overlap
• One delay is dominant over another
• The critical path shifts during the project

The real difficulty in concurrent delay analysis is evidential. Construction projects rarely maintain sufficiently detailed contemporaneous records to demonstrate precisely what would have occurred “but for” each delay event. This makes concurrent delay disputes highly technical and often dependent on expert analysis.

Legal Principles Governing Concurrent Delay

Concurrent Delay and Extension of Time (EOT)

The leading authority on concurrent delay under English law is Henry Boot Construction v Malmaison Hotel.

In this case, Rupert Jackson (then HHJ Dyson) established a key principle:

Where there is concurrent delay, and one cause is a Relevant Event while the other is not, the contractor is entitled to an Extension of Time (EOT).

This means:

• Concurrent delay does not eliminate EOT entitlement
• The employer cannot rely on contractor delay to deny time relief for employer-caused delay

This principle protects contractors from being unfairly penalized in cases of concurrent delay.

Concurrent Delay and Prolongation Costs

While concurrent delay generally preserves EOT entitlement, the position on financial recovery is more restrictive.

In Multiplex v Honeywell, the court confirmed that:

• During periods of concurrent delay,
• The contractor is typically not entitled to recover prolongation costs

This is because:

• The contractor’s own delay is contributing to the same period of delay
• Therefore, cost recovery is not justified for that overlapping period

This distinction between time entitlement and cost entitlement is critical in any concurrent delay analysis.

SCL Protocol Approach to Concurrent Delay

The Society of Construction Law Delay and Disruption Protocol (2nd Edition, 2017) provides structured guidance on concurrent delay.

Under Core Principle 10:

• In cases of true concurrent delay:
  • The contractor is entitled to EOT
  • Neither party recovers prolongation costs

This reflects a balanced approach, ensuring that concurrent delay does not unfairly benefit or penalize either party.

Practical Application of Concurrent Delay Analysis

For Contractors

When dealing with concurrent delay, contractors should:

• Assert EOT entitlement for employer-caused delay, even where concurrent delay exists
• Focus on identifying periods where:
  • Employer delay is dominant, or
  • Employer delay is the sole cause

These periods offer the strongest basis for recovering both:

• Time (EOT)
• Prolongation costs

A strategic approach to concurrent delay claims is essential to maximize entitlement.

For Employers and Contract Administrators

Employers must approach concurrent delay with analytical rigor.

Key considerations include:

• Simply alleging concurrent delay is insufficient
• The employer must demonstrate that:
  • Contractor delay independently delayed completion
  • The same delay would have occurred regardless of employer events

Without clear programme evidence, arguments based on concurrent delay are unlikely to succeed.

Risks Associated with Concurrent Delay

Contractor Risks

• Failure to properly document concurrent delay events
• Loss of EOT entitlement due to weak evidence
• Inability to recover prolongation costs

Poor management of concurrent delay can result in the entire delay being attributed to the contractor.

Employer Risks

• Ignoring employer-caused concurrent delay
• Failure to grant EOT where required
• Exposure to “time at large”

If concurrent delay is not properly recognized, the employer may lose the right to impose liquidated damages, significantly increasing financial exposure.

Mitigation Strategies for Concurrent Delay

Effective management of concurrent delay requires a proactive and structured approach:

During Project Execution

• Maintain detailed contemporaneous records
• Regularly update the construction programme
• Identify and track all delay events

During Delay Analysis

• Assess concurrent delay on a period-by-period basis
• Identify dominant and critical delay events
• Apply consistent delay analysis methodologies

In Dispute Situations

• Engage delay analysis experts
• Use programme-based techniques (e.g., time impact analysis)
• Align analysis with the Society of Construction Law Protocol

A disciplined approach significantly improves outcomes in concurrent delay disputes.

Conclusion: Concurrent Delay Requires Precision and Strategy

Concurrent delay is not simply a technical concept — it is a decisive factor in determining time and cost entitlement in construction projects.

While the legal principles governing concurrent delay are relatively well established, their application depends heavily on:

• Project records
• Programme analysis
• Contractual interpretation

The key takeaway is clear:

• EOT entitlement is generally preserved in concurrent delay
• Prolongation cost entitlement is significantly restricted

Contractors and employers who understand and properly manage concurrent delay are far better positioned to avoid disputes, protect their contractual rights, and achieve fair project outcomes.