A Deed of Variation, or DoV for short, is a formal legal document used to change the terms of an existing contract. In the context of the UK construction industry, it is most commonly used to amend building contracts after they have been executed. These amendments can relate to the scope of works, project timelines, financial arrangements, or the responsibilities of the parties involved. A key feature of a deed is that it does not require consideration, something of value exchanged, to be enforceable. This makes it useful when only one party is providing a benefit or when changes are agreed without additional payment.
Application in UK Construction Projects
In construction, numerous situations can arise where a deed of variation is appropriate. For example, after signing a JCT (Joint Contracts Tribunal) or NEC (New Engineering Contract), the client and contractor may agree that the original design requires significant changes, or that the programme needs to be extended. While minor variations are often managed through standard variation instructions or compensation events, a deed of variation is used when the change is substantial or when the contract explicitly requires a formal deed.
Deeds of variation are especially important in:
- Design and build contracts
- Public procurement projects
- Large infrastructure schemes
These environments often require strict legal certainty and audit trails to ensure compliance and accountability.
Legal Requirements
To be valid, a deed of variation must meet specific legal criteria:
- It must be in writing.
- It must clearly state that it is a deed.
- It must be executed properly: signed by authorised parties and witnessed (or sealed, depending on the organisation).
- It must be delivered as a deed, which generally means all parties have signed and dated it.
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Advantages of a Deed of Variation
The main benefits of using a deed of variation in construction include:
- Clarity – providing a clear, written record of agreed changes.
- Enforceability – even without consideration, the deed is legally binding.
- Risk management – helping prevent disputes over verbal or informal agreements.
This makes it a useful tool when adapting a project to changing circumstances, while still protecting the legal interests of all involved.
Risks and Considerations
Despite its benefits, a poorly drafted deed can create ambiguity or unintentionally override important terms in the original contract. It may also result in parties waiving rights or obligations without realising it. For this reason, deeds of variation should always be carefully prepared, ideally with the input of legal professionals and Commercial Managers.
