What a provisional sum in your tender actually means

A provisional sum is a line in a tender where the builder writes a number they do not stand behind. If the real cost is higher, you pay the difference. There are honest uses for it — a client-selected finish nobody has chosen yet, a service connection the network operator has not priced. What it should not cover is ground conditions, because the builder can go and find out, and you cannot. When you compare tenders, add up the provisional sums first. The cheapest headline number with $400,000 of provisional sums under it is not the cheapest tender; it is the one with the most unknowns pointed at you.