← All Insights

Building Quotes

Provisional Sums Explained: How Building Quotes Hide Real Costs

Simple guide explaining provisional sums in building quotes, with examples and practical tips for homeowners.

TL;DR A provisional sum is an estimated allowance for work that cannot be fully priced when the quote is prepared. It is not a fixed price. If the real cost ends up higher, you usually pay more. Provisional sums are common and not automatically a problem—but too many of them, or vague low allowances, can make a quote look far cheaper than the likely real cost. Simple Explanation Think of a provisional sum as a “best guess allowance” inside the quote. The builder is saying: “We know this part of the job is coming, but we cannot price it exactly yet.” Common Examples Provisional sums often appear for: excavation rock removal drainage retaining walls piering site levelling external service works some finish items where details are unresolved Why They Matter A quote with low provisional sums c…