Answered: NEC ECS: How should you assess the cost of delay under option C?

They are largely right.

See the detail of the SSCC : i.e. site management people who on site longer are paid at cost with uplift (percentage for WA overheads). Accommodation is within Equipment. General construction plant, which will be on-site longer as a result of prolongation is within Equipment  etc.

Some costs though will be within the percentage for WA overheads so you need to look at what is within that percentage to avoid double payments.