Prime cost items and provisional sums

Most building contracts include provision for prime cost items and provisional sums. A prime cost item is an allowance in the contract for the supply of necessary items not yet finally selected, for example taps or door furniture. A provisional sum is an allowance in the contract for the cost of foreseeable necessary work, including the supply of materials not fully described or detailed at the time that the contract commenced, for example joinery items or a service connection.