A necessary evil is something unpleasant or unwelcome that has to be accepted in order to achieve a particular result.
It is not a technical term, but it is often used informally on construction projects to describe costs or activities that add nothing visible to the finished building yet cannot be avoided. Clients sometimes see preliminaries, temporary works, traffic management or contingency allowances this way. Part of the quantity surveyor’s job is to explain why these costs are needed and to make sure they are reasonable, properly scoped and not duplicated elsewhere in the price. Typical examples include:
- site set up, welfare facilities and security
- temporary works such as scaffolding, propping and shoring
- statutory approvals, surveys and inspections
Related terms: preliminaries, temporary works, contingency.
