Prime Cost sums in construction (PC or PC sums) is a sum in the contract to provide an idea of the basic cost/price of some material or items for pricing the tender. Most of the time, for the material items, which are with a range of a price (like Tiles, Sanitary fitting, Light fittings, etc.) to price bid on an equal basis.

It is a sum provided for work or services to be executed by a nominated subcontractor, a statutory authority or public undertaking or for materials or goods to be obtained from an approved supplier.

The main contractor is eligible to get his mark up and attendance costs to the above allowance.

Benefits of allowing Prime cost sums also later on client or consultant can make certain changes of the specification changes to the prime cost items without causing any variations.

Actual cost may be higher or lower than the allowed Prime cost sum, and in such cases, the contractor is required to provide all the relevant cost details with supportive documents & justify this actual cost.

Summary:

A PC sum is an allowance/money provision.
It is provided for getting work or materials from a nominated subcontractor or supplier.
Main Contractor is eligible for Profit Mark up or attendance costs.
PC Sums are added items like; tiles, sanitary items, lighting fixtures, etc., to get an idea of the price of such particular material or item to be priced by the tenderer.
It is provided for a certain element of the works that are not adequately described, or such details can not be given at the tender stage for tenderers to price accurately.