Daywork is a method of valuing work on the basis of the labour, plant and materials actually used, plus agreed percentages, typically used where work cannot sensibly be measured or priced in advance.
Its currency is the daywork sheet: a dated record of who worked, for how long, with what plant and materials, ideally signed by the supervising party at the time. Unsigned or late sheets are where daywork value goes to die.
Photographs and daily records that corroborate the resources claimed make daywork accounts hard to argue with; their absence makes them easy to cut.