With the UK construction industry about to enter its traditional two-week shutdown, clients with slipping programmes often look for one last lever:
Pay the contractor an acceleration fee to work over Christmas.
On paper it seems simple: Two lost weeks + extra labour = recovered programme.
In practice? I’ve rarely seen it deliver meaningful time savings unless it is structured properly, contractually robust, and monitored with absolute clarity.
Christmas acceleration is full of traps:
- Site conditions are less productive.
- Labour supply is limited – and expensive.
- Supply chain availability is greatly reduced.
- Supervision levels drop.
- Quality issues increase.
And critically: if you don’t define what “acceleration” actually means, you’ll pay for effort rather than outcomes.
The Mistake: Paying for Activity Instead of Results
I’ve seen many projects fall into this: They agree a lump-sum premium for Christmas working, with no baseline, no clear methodology, and no measurable outputs.
Come January, the contractor says: “We tried, but due to supply issues, access constraints, and reduced staff, we couldn’t get as much done as planned.”
And the client discovers:
There was no obligation to deliver anything specific.
Acceleration became a best endeavours exercise, not a contractual commitment.
RICS guidance on programme and commercial control is clear on this point: Any change to methodology or sequence must be measurable, evidenced, and linked to defined deliverables. (Source: RICS “Managing the Programme”, RICS Project Management Guidance Note.)
The Fix: Treat Acceleration Like a Mini-Contract in Its Own Right
Acceleration should be approached with the same discipline as procurement.
Here’s a model I’ve seen work:
1. Start with a clear baseline
You can’t measure acceleration unless you know:
- The current planned completion date
- Critical path activities
- Remaining float (if any)
- What specific activities are causing delay
Without this, any discussion on acceleration is not productive.
2. Define the acceleration strategy
Before you talk money, ask the contractor:
- What exactly will you do differently?
- How will this reduce the programme?
- What risks do you foresee?
- What labour, supervision and management will be on site?
- Which supply chain members have confirmed availability?
- How does this impact quality assurance?
If they can’t answer these in detail, then acceleration is a gamble.
3. Attach the programme gain to clear, measurable outputs
Good practice is to agree:
- A revised, contractually binding programme
- A detailed method statement
- Output-based milestones
- KPIs for labour levels, supervision, inspections
- Interim deliverables (e.g., “screed complete by 22 Dec”)
If the outputs aren’t met, then the acceleration fee is reduced, withheld, or re-negotiated.
4. Define payment as “pay for results”, not “pay for trying”
There are two commercially robust models:
Option A: Lump-sum for guaranteed programme gain
The contractor gets the fee only if the agreed reduction is achieved. This aligns incentives perfectly.
Option B: Targeted milestone payments
Release the fee in tranches only when milestone outputs are verified.
If they fail to deliver, the client retains the value.
This is consistent with RICS commercial management principles: payment must be tied to verified progress, not assumptions. (Source: RICS Quantity Surveying Practice Guidance – Valuation of Variations.)
5. Ensure Quality Control Doesn’t Collapse
A rushed Christmas push can lead to:
- Hidden defects
- Failed inspections
- Rework in January
If the contractor is accelerating, their QA regime must accelerate too.
Get this documented and resourced. No shortcuts.
6. Robust Monitoring
Daily records. Daily sign-offs. Daily labour return sheets. Daily programme tracking.
A loose approach here is how clients end up paying for bodies on site, not for progress.
When Christmas Acceleration Does Work
In my experience, it delivers when:
- The supply chain is genuinely available
- The contractor produces a credible methodology
- There is a clear line of sight to reducing the critical path
- The client sets firm outputs
- Payments are tied to results
- Quality and supervision are maintained
- Records are watertight
Get these right, and acceleration can buy you real programme certainty. Get them wrong, and you’ll come back in January having spent money for very little gain.
Final Thought: Don’t Let Christmas Panic Drive Bad Decisions
Panic buys rarely deliver value.
If the project needs acceleration, treat it with the same discipline you’d apply to procurement, cost control, or risk management.
The client’s leverage is strongest before the acceleration is agreed. Once you’ve signed it, you’re relying entirely on goodwill and supervision.
And goodwill doesn’t shift a critical path.
Need Help?
Need some help with accelerating your programme? Send us an email at info@ethoseq.co.uk.
General Disclaimer
This article provides general guidance based on industry best practice, including RICS principles. It should not be relied upon as formal advice. Project specifics vary, and clients should seek independent professional or legal advice before acting on any of the topics discussed.
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