Extended site overheads: what each week the job runs long costs, and how to work it out
The laboratory job's finish forecast moves nine weeks later. The cost report still carries the original trailer and staff allowance. The project manager needs to estimate the extended site period without assuming every budget item continues unchanged.
Identify which site resources will continue over the longer period, price their actual expected duration and revise the allowance as the resource plan changes. Separate these time-related costs from work priced by quantity or one-time setup. The SCL Protocol discusses extended time-related site resources, while making recovery subject to contract and cause. Its UK guidance does not establish Canadian entitlement; forecasting the exposure and deciding recovery are separate tasks.
Price the resource plan, not a blanket multiplier
- Confirm the extended period. Use the current schedule review and stated assumptions, identifying the affected phases. Keep the original and revised dates for comparison. Do not translate every activity delay into extra whole-site weeks without checking the completion effect.
- List the continuing resources. Review site staff, accommodation, fencing, temporary services and booked equipment with their owners. Confirm whether insurance or other charges actually increase with time before including them. Remove items that finish or return before the extended period.
- Price each component on its charging basis. Identify salary allocation, rental period, utility allowance and any return or cancellation condition. Convert to a weekly planning rate only where that is useful and supported; retain the underlying invoice or agreement.
- Split the period when the plan changes. A full crew and two trailers may be needed initially, followed by a smaller closeout presence. Price those stages separately. A single average should not conceal a resource release that can be planned now.
- Check the forecast for overlap. Compare the extension allowance with existing remaining costs, event codes and replacement-work prices. Include the incremental exposure once. Keep head-office costs separate for the company's adviser to assess rather than adding an unexplained percentage.
- Retain records for the commercial review. Link actual charges and resource dates to the relevant event and schedule evidence. Send notice and recovery questions through the contract process. A forecast weekly allowance is not automatically the amount recoverable from the owner.
Common mistakes
- Extending one-time mobilization costs as though they recur weekly.
- Keeping equipment in the allowance after its planned return.
- Adding the same site-staff cost in both an event total and the extended-period line.
Checklist
Support each added week
- Completion effect and assumptions.
- Resources actually expected to remain.
- Charging basis and release dates.
- Different stages priced separately.
- Overlap with existing allowances removed.
- Actual records retained for review.
Check your understanding
The job runs nine weeks longer, but a trailer is needed for only six. Should its weekly rate be multiplied by nine?
