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
Guidance notes to prepare for April ERA changes
From the Electrical Contractors' Association Employee Relations team.
Significant changes to be seen from the new ERA in 2026 and 2027, starting on 6 April 2026.
First aid in the modern workplace with St John Ambulance.
Ireland's National Residential Retrofit Plan
Staged initiatives introduced step by step.
Solar panels, pitched roofs and risk of fire spread
60% increase in solar panel fires prompts tests and installation warnings.
Modernising heat networks with Heat interface unit
Why HIUs hold the key to efficiency upgrades.
Reflecting on the work of the CIOB Academy
Looking back on 2025 and where it's going next.
Procurement in construction: Knowledge hub
Brief, overview, key articles and over 1000 more covering procurement.
Sir John Betjeman’s love of Victorian church architecture.
Exchange for Change for UK deposit return scheme
The UK Deposit Management Organisation established to deliver Deposit Return Scheme unveils trading name.
A guide to integrating heat pumps
As the Future Homes Standard approaches Future Homes Hub publishes hints and tips for Architects and Architectural Technologists.
BSR as a standalone body; statements, key roles, context
Statements from key figures in key and changing roles.
ECA launches Welsh Election Manifesto
ECA calls on political parties at 100 day milestone to the Senedd elections.
Resident engagement as the key to successful retrofits
Retrofit is about people, not just buildings, from early starts to beyond handover.
Plastic, recycling and its symbol
Student competition winning, M.C.Esher inspired Möbius strip design symbolising continuity within a finite entity.
Do you take the lead in a circular construction economy?
Help us develop and expand this wiki as a resource for academia and industry alike.
Warm Homes Plan Workforce Taskforce
Risks of undermining UK’s energy transition due to lack of electrotechnical industry representation, says ECA.
Cost Optimal Domestic Electrification CODE
Modelling retrofits only on costs that directly impact the consumer: upfront cost of equipment, energy costs and maintenance costs.























