Which Preliminaries and Time-Related Overheads Can You Recover?

When a project is delayed by an event the Employer is responsible for, the money is in the preliminaries. The direct cost of the delayed work is usually modest; it is the site establishment ticking over week after week - the staff, the accommodation, the plant, the facilities - that drains the margin. But a prolongation claim is not a licence to sweep your entire prelims schedule into a claim and multiply by the weeks of delay. Only the costs that are genuinely time-related, and that you can actually evidence, will survive. Get the distinction wrong and a strong entitlement collapses on valuation.

Time-Related Versus Fixed and Value-Related Prelims

The single most important distinction in any prolongation claim is between time-related preliminaries and everything else. Time-related prelims are costs that accrue with the passage of time on site - you incur them every week the project runs, so if the project runs longer, they cost more. Fixed prelims, by contrast, are one-off costs incurred regardless of duration: mobilisation and demobilisation, setting up the site compound, a one-time design fee. Extending the programme does not increase them, so they do not belong in a prolongation claim.

Value-related prelims are the third category and the one that trips contractors up most. These are costs that scale with the volume or value of work rather than with time - certain insurances, some bonds, testing costs tied to quantities. A delay that does not add work does not add these costs, so claiming them as prolongation is wrong. The discipline is to go through the prelims schedule and label each item time-related, fixed, or value-related before you build any claim. Only the time-related column is prolongation territory, and being rigorous about that classification is what makes the rest of the claim credible.

Site Management and Supervision Staff

Site staff are usually the largest recoverable item. Where a project manager, site agent, engineers, quantity surveyors, and supervisors are retained on the project for the extended period because the works are still running, their prolonged cost is a classic time-related preliminary. The claim is valued on the actual cost of keeping those people on the project for the additional period - salaries, on-costs, accommodation and subsistence where applicable - not on a notional rate plucked from the tender.

The evidential trap is proving that the staff were actually there, actually working on this project, and were retained because of the delay rather than for reasons of your own. This is where site records earn their keep: organisation charts, timesheets, site diaries, and payroll records that place named individuals on the project across the prolonged weeks. A claim that asserts a management team stayed on without the records to prove who was present and when is the easiest thing for an assessor to discount. The contemporaneous records that make or break a delay claim are exactly these.

Accommodation, Facilities and Site Establishment

The running cost of the site establishment is squarely time-related and usually recoverable for the prolonged period. Site offices, welfare and canteen facilities, stores, hoarding and fencing maintenance, and the utilities and services that keep the compound running all accrue weekly. If the compound has to stand for additional weeks because the works are delayed, the additional hire, running, and servicing costs of that establishment are the meat of a prolongation claim alongside the staff.

Care is needed on two fronts. First, distinguish the one-off establishment costs - the initial setup and eventual removal, which are fixed - from the ongoing weekly running costs, which are the recoverable part. Second, value the extended period on what was actually incurred, using hire invoices, utility bills, and rates schedules for the prolonged weeks, not on the tendered weekly allowance which may bear little relation to reality. The tender figure sets expectations; the actual cost records substantiate the claim. Where the two diverge, it is the evidenced actual cost that an assessor will accept.

Plant, Scaffolding and Site Transport

Plant is recoverable when it is genuinely time-related and genuinely idle or retained because of the delay - and this is one of the most contested lines. Standing tower cranes, hoists, site accommodation units, welfare units, and general site plant that must remain on site through the prolonged period can be claimed for that period. The essential distinction is between plant that is time-related, sitting there because the site is still open, and plant whose cost is tied to the volume of work it performs, which is not prolongation.

The valuation question is whether to claim on hire cost or on a lower standing rate. Externally hired plant that continues to be paid for at hire rates through the delay is straightforward to evidence from invoices. Owned plant is harder: you are claiming the cost of it being tied up on this project rather than earning elsewhere, and assessors will scrutinise whether it was truly retained by the delay or would have sat idle anyway. Records showing the plant on site, its hire or internal rate, and the reason it could not be released are what turn a plant claim from an assertion into a recovery.

A Line-by-Line View of Recoverability

It helps to see the categories side by side, because the recoverability of any given item depends entirely on which bucket it falls into rather than on its label in the bill.

Prelim item | Typical category | Recoverable in prolongation Site management and supervision staff | Time-related | Yes, for the prolonged period with records Site offices and welfare running costs | Time-related | Yes, ongoing running cost only Standing cranes, hoists, site plant | Time-related | Yes, if retained due to delay Utilities, security, cleaning | Time-related | Yes, for the extended weeks Mobilisation and demobilisation | Fixed | No, unaffected by duration Initial site setup and final clearance | Fixed | No, one-off cost Quantity-based insurances and testing | Value-related | No, scales with work not time

The table is a starting point, not a verdict. Any of these can shift category depending on how your contract prices them and how the delay actually affected your site, which is why the classification exercise has to be done against your specific prelims schedule and your specific facts rather than from a generic list.

Records, Causation and Building a Claim That Holds

Recoverability is only half the battle; the other half is causation. It is not enough to show that a cost is time-related and that it was incurred - you must connect it to the specific delaying event the Employer is responsible for, and to a period of critical delay that entitles you to compensation. Prolongation is paid for the period of Employer-caused critical delay, valued at the cost actually incurred in that period, which is why the assessment window matters as much as the cost itself. Claiming your average weekly prelims across the whole overrun, regardless of who caused what, is the error that sinks otherwise good claims. For the full picture of what genuinely qualifies, see what is a prolongation claim and what actually qualifies.

The through-line is evidence. Timesheets, site diaries, plant and hire records, payroll, invoices, and progress records are what convert a theoretically recoverable cost into money actually paid. Contractors lose recoverable prelims not because the entitlement was weak but because they cannot prove who was on site, what plant stood, and why the delay caused it. Assembling and presenting that evidence into a claim that an assessor cannot easily discount is precise, specialist work, and it is exactly what our cure service is built to deliver when the money on the line justifies getting it right.

Frequently Asked Questions

What is the difference between time-related and fixed preliminaries?

Time-related preliminaries accrue with the passage of time on site - staff, site accommodation running costs, standing plant, utilities - so a longer programme costs more of them, which is why they are the basis of a prolongation claim. Fixed preliminaries are one-off costs incurred regardless of how long the job runs, such as mobilisation, demobilisation, and initial site setup. Extending the programme does not increase fixed costs, so they are not recoverable as prolongation. There is also a value-related category - costs that scale with the volume of work rather than time - which is likewise not prolongation.

Can I claim my whole prelims schedule for the delay period?

No, and trying to is a common way to lose an otherwise good claim. Only the genuinely time-related items are recoverable, and only for the period of Employer-caused critical delay, valued at the cost actually incurred. Fixed costs like mobilisation and value-related costs like quantity-based insurances do not belong in the claim. The correct method is to classify each line of your prelims schedule as time-related, fixed, or value-related, then evidence the actual cost of the time-related items across the specific prolonged period rather than applying an average weekly rate to the whole overrun.

How do I value prolonged site staff - tender rates or actual cost?

Actual cost, evidenced. Prolongation compensates you for the real cost of retaining site management and supervision on the project for the additional period, so you value it on actual salaries, on-costs, and associated expenses for the named individuals who were genuinely there. Tendered rates set expectations but are frequently discounted by assessors because they may not reflect what was actually incurred. Support the figure with organisation charts, timesheets, site diaries, and payroll records that place specific people on the project across the prolonged weeks, and that show they were retained because of the delay.

Is idle or standing plant recoverable in a prolongation claim?

It can be, if it was genuinely time-related and retained on site because of the delay rather than for your own convenience. Standing cranes, hoists, and site accommodation that must remain through the prolonged period are recoverable for that period, valued on hire cost for externally hired items or a defensible internal rate for owned plant. The scrutiny falls on causation: an assessor will ask whether the plant was truly tied up by the Employer-caused delay or would have sat idle anyway. Records showing the plant on site and the reason it could not be released are essential.

What records do I need to support a preliminaries claim?

The records that prove presence, cost, and causation. For staff: organisation charts, timesheets, site diaries, and payroll placing named people on the project. For establishment and plant: hire invoices, utility bills, rates schedules, and logs showing what stood and for how long. For causation: progress records and programmes linking the extended period to the specific Employer delay. Contemporaneous records created as the work happened carry far more weight than anything reconstructed later. Most lost prolongation money is lost not on entitlement but on the inability to evidence who and what was on site, and why.

Classify every prelim correctly, prove it with contemporaneous records, and tie it to the Employer's delay - anything less leaves recoverable money on the table.

Note: This article is general information on prolongation and preliminaries recovery and is not legal advice; recoverability depends on your specific contract, prelims pricing, and the facts of the delay.