Source: https://www.quantsurv.com/library/delay-and-disruption Content format: Markdown version of the public page. Content reviewed: 2026-10-11 # Delay, disruption and extra cost: the differences Finishing later, working less efficiently and spending more are different problems. Understanding the distinction helps you explain what happened on your package. by [Jack Butler-Kettle]() ยท About 3 min readShare ## The answer Delay concerns time; disruption concerns how efficiently work is performed. Their financial consequences need separate explanation and evidence. An extension of time does not automatically establish a right to additional money. ## Key differences Scroll across to read all columns. Delay, disruption and additional cost compared | Question | Delay | Disruption | | --- | --- | --- | | What is affected? | The timing of activities or completion | The efficiency of performing work | | Evidence | Programme, progress, event and sequence records | Resource allocations, output and comparable working conditions | | Assessment | Explain the event's effect on the relevant completion obligation | Explain the productivity effect, comparison basis and other causes | | Money | An extension alone does not establish recoverable additional cost | Extra resources alone do not establish recoverable loss | | Overlap | Check time, prolongation costs and separately assessed disruption | Avoid counting costs already included in prolongation or variations | ### Describe the effect on your work Identify the affected activity and event. Explain whether work started later, lasted longer, changed sequence or needed additional resources. A delayed activity may not delay completion. Disrupted work may finish on time through extra labour or changed methods. The [measured-mile example]() shows a productivity comparison and explains why the arithmetic alone does not prove a claim. The [SCL Delay and Disruption Protocol]() offers professional guidance on assessing these matters. It is not legislation and does not replace your contract. ### Check time entitlement separately Read [how an extension of time is calculated]() before treating an interruption as an equal extension. Check [JCT time and money routes]() separately. Keep the agreed programme, revisions and progress records. Explain how the event affected the work that controls your completion date. Identify relevant notices and update obligations. Do not wait for the full financial effect before checking a notice deadline. Separate events attributable to different parties and periods that overlap. Complex causation or competing delays may require specialist programme analysis. ### Build the financial explanation Identify the contractual basis for additional payment before calculating it. Record actual additional site costs and explain why the event caused them. Keep resource and output information if productivity changed. Comparing totals without allowing for different conditions can give a misleading result. The [head office overheads calculator]() compares formulas. It does not establish that overheads were lost or that a period is compensable. [Delay and disruption cost recovery]() brings the event records, programme evidence and financial calculation together into an explained claim. ### Keep records that connect event and effect Save daily labour and plant records, work locations, access restrictions, instructions, photos, deliveries and contemporaneous programme updates. Use an event chronology linking each event to affected activities and supporting files. Explain gaps rather than inventing missing records. See [claims records and evidence]() for a practical structure. This is general learning for the UK construction industry. Check your governing law, contract form and amendments. Statutory procedures differ across England, Wales, Scotland and Northern Ireland. ## Example ### The facts A mechanical subcontractor works in smaller areas than planned because preceding works are incomplete. They add labour and still meet their completion date. ### What happens 1. They record available work areas and daily labour against output. 2. They compare the working conditions with their original plan and identify other possible causes of reduced output. 3. They check their contractual route and explain any claimed additional cost separately from completion delay. ### What this shows The example concerns possible disruption without an assumed extension of time. Additional labour alone does not prove recoverable loss. ## Sources 1. [Delay and Disruption Protocol, 2nd edition, February 2017](). Society of Construction Law. [Browse the Library]()