Contingencies in construction
Contingencies are downside risk estimates that make allowance for the unknown risks associated with a project.
Typically, contingencies refer to costs, and are amounts that are held in reserve to deal with unforeseen circumstances. However, they may also refer to other aspects of the project, for example, the programme may include a contingency where it is important that a specific completion date is achieved.
A contingency may also refer to part of a contingency plan, which is a plan that can be enacted to mitigate project risks, such as adverse weather, an industrial dispute, supplier failure, and so on.
Monetary contingencies are typically referred to in relation to the overall client for a project. However, other parties in the supply chain are also likely to include contingencies in their cost planning.
While it is advisable for clients to hold a contingency, they might no wish to share this information with the rest of the project team, who may see a contingency as a license to exceed the budget in the knowledge that the client has a reserve that can be spent.
Contingencies are often expressed in terms of percentages. The percentage contingencies applied are at their greatest in the early stages of the project when there are the greatest number of possible risks. But they can then be reduced as better particulars about the project become available and some risks have passed or been overcome.
An example of how a contingency might be reduced during a project is set out below:
- At the preliminary business plan stage, total cost estimates might include a 15% contingency.
- In the elemental cost plan this might reduce to 10% of fees and construction costs.
- On awarding the contract, 5% of the contract value might be included as contingency in the cost plan.
In addition to a contingency, the client is likely to hold retention. Retention is a percentage (often 5%) of the amount certified as due to the contractor on an interim certificate, that is deducted from the amount due and retained by the client. The purpose of retention is to ensure that the contractor properly completes the activities required of them under the contract. Retention can also be applied to nominated sub-contractors, and the main contractor may also apply retention to domestic sub-contractors.
[edit] Related articles on Designing Buildings
Featured articles and news
We're expanding our collaborative mission by launching DB Intelligence, an exclusive market research advisory panel. Built environment professionals can now get paid to share their expertise on industry trends, products and services.
Panel members receive direct financial incentives for participating in research projects like short surveys, 1-2-1 interviews and focus groups. Register today to shape the future of the construction sector.
Building Control Independent Panel final report
A precis of a key report led by Dame Hackitt with full recommendations and link to the government response.
Guide to ISO 19650 for Architecture Firms (2026)
A user gives their low down.
A UK training and membership provider for mould remediation professionals.
Building Safety recap April, 2026
A short and longer run-through of the month, with links to further information and sources.
CIAT May 2026 briefing.
Independent NSI and BAFE study exploring how organisations are changing the way they buy fire safety services.
From medieval scribes to modern word art.
ECA welcomes crackdown on late payment and push for clean energy, whilst CIOB seek fixed cladding removal timeframes.
Cyber Security in the Built Environment
Protecting projects, data, and digital assets: A CIOB Academy TIS.
Managing competence in the built environment
ITFG publishes new industry guide on how to meet the ICC principles.
The UK's campaign to reduce noise pollution: Mythbusting, articles and topic guides.

















