Prime cost contract
Prime cost contracts (such as JCT PPC 11) are sometimes called cost plus contracts or cost reimbursement contracts.
Prime cost contracts are used where an early or immediate start on site is required even though design information is not complete.
This method of procurement is not generally recommended, but it can be useful under particular circumstances where an immediate start on site is necessary (for example for urgent alteration or repair work, or if there has been a building failure or a fire, requiring immediate reconstruction or replacement of a building so that the client can continue to operate their business).
Tendering proceeds based on an outline specification, any drawings and an estimate of costs. The contractor is paid the prime cost (the actual cost of labour, plant and materials) and a fee for overheads and profit. The fee can be agreed by negotiation or by competition, and may be a lump sum (which it may be possible to adjust if the actual cost is different from the estimate), or a percentage of the prime cost (which it may be possible to revise if the client changes the nature of the works).
Other basis for payment are possible, including combinations of lump sum and percentage fees. For example, it might be possible to fix some elements of overheads whilst applying a percentage to other elements and to profit.
This is a high risk form of procurement for the client as they are reliant on the contractor working efficiently and procuring sub-contracts economically. Sub contracts may be procured competitively, but there may be little incentive for the contractor to secure or select economic bids. Some of these difficulties can be mitigated if a partnering relationship has been established between the client and the contractor.
NB: Some people consider that a cost reimbursable contract or cost plus contract is one in which the client takes all the risk, whereas a prime cost contract is one in which the cost of the works packages (the prime cost) are reimbursed but the main contractor takes a risk on staffing, overhead costs and profit which might be tendered on a fixed price.
[edit] Related articles
Featured articles and news
Buildings that changed the future of architecture. Book review.
The Sustainability Pathfinder© Handbook
Built environment agency launches free Pathfinder© tool to help businesses progress sustainability strategies.
Government outcome to the late payment consultation, ECA reacts.
IHBC 2025 Gus Astley Student Award winners
Work on the role of hewing in UK historic conservation a win for Jack Parker of Oxford Brookes University.
Future Homes Building Standards and plug-in solar
Parts F and L amendments, the availability of solar panels and industry responses.
How later living housing can help solve the housing crisis
Unlocking homes, unlocking lives.
Preparing safety case reports for HRBs under the BSA
A new practical guide to preparing structural inputs for safety cases and safety case reports published by IStructE.
Male construction workers and prostate cancer
CIOB and Prostate Cancer UK encourage awareness of prostate cancer risks, and what to do about it.
The changed R&D tax landscape for Architects
Specialist gives a recap on tax changes for Research and Development, via the ACA newsletter.
Structured product data as a competitive advantage
NBS explain why accessible product data that works across digital systems is key.
Welsh retrofit workforce assessment
Welsh Government report confirms Wales faces major electrical skills shortage, warns ECA.
A now architectural practice looks back at its concept project for a sustainable oceanic settlement 25 years on.
Copyright and Artificial Intelligence
Government report and back track on copyright opt out for AI training but no clear preferred alternative as yet.
Embedding AI tools into architectural education
Beyond the render: LMU share how student led research is shaping the future of visualisation workflows.
Why document control still fails UK construction projects
A Chartered Quantity Surveyor explains what needs to change and how.
Inspiration for a new 2026 wave of Irish construction professionals.
New planning reforms and Warm Homes Bill
Take centre stage at UK Construction Week London.























Comments
For small alternation project of 8 storey building, what is the advantage of using prime cost contract?
Unless an immediate start is needed - for example if there is some danger or urgency, it is difficult to see what the advantage would be over a traditional contract.