Allowance

Allowances fill the gaps that exist at every estimate stage: the design shows a pump but not yet its foundations, a route but not yet its supports. The estimator carries a judged amount — a percentage on the measured quantities or a lump figure per item — so the estimate reflects the whole expected scope, not just the drawn part. As design matures, allowances are progressively replaced by measured quantities, and watching that replacement is one of the cleanest indicators of estimate maturity.

The distinction from contingency is definitional and worth policing: an allowance covers a known, specific item awaiting detail and sits inside the base estimate; contingency covers the unspecified residual uncertainty and sits on top of it. When allowances and contingency both quietly cover the same growth, the estimate is padded twice; when each assumes the other covers it, the growth is covered by neither. Every allowance should be listed, justified and closed out by name — an allowance nobody can enumerate is just contingency hiding in the base.