What happens if the work overruns?
It depends entirely on your contract. A standard form contract sets a completion date and provides for extensions of time only for defined reasons — weather, client variations, unforeseen ground conditions. Without a contract specifying dates and a variations process, there is very little you can do.
Some overrun causes are legitimate and a fair contract allows for them: exceptional weather, ground conditions nobody could have foreseen, delays caused by the client's own changes, or late decisions on materials. A standard form contract handles these through a formal extension of time, so the completion date moves for a recorded reason rather than quietly slipping.
Client variations are the largest single cause of overrun, and they are usually invisible while they happen. Each change of mind after work has started has a time cost as well as a money cost. Insisting that every variation is confirmed in writing with both a price and a time implication before it is carried out is the most effective protection — and it protects the builder equally.
Where a project overruns without a legitimate cause, a standard form contract may provide for liquidated damages: a pre-agreed sum per week of delay. These are only enforceable if written into the contract at the outset and set at a genuine estimate of your loss. This is a strong argument for using a proper contract rather than a quote and a handshake, and for agreeing a realistic completion date rather than an optimistic one.
More on this in living through the works, or see all 42 questions.
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