Provisional sum (and prime cost / PC sum)

A provisional sum is an allowance included in a renovation quote or contract for work that isn't fully designed or priced yet — a placeholder figure (e.g. 'provisional sum for tiling' before you've chosen the tile, or for works behind a wall that can't be seen). It is not a fixed price: once the work is specified or uncovered, the provisional sum is reconciled to the actual cost, so the final bill can go up or down against it. A closely-related term is a prime cost (PC) sum, an allowance for a supply item (e.g. the sanitaryware or the kitchen) whose exact product hasn't been selected. Why this matters when comparing renovation quotes: a quote that looks cheap may be loaded with provisional/PC sums, meaning large parts aren't actually fixed and could rise — so you compare how much of each quote is firm versus allowance, and pin down as much as possible before signing (see contract payment terms). A finishing and fit-out contractor should be transparent about which items are provisional and why.