Lower uncertainty
New construction with a known substrate and finalized product can be more predictable.
Higher uncertainty
Renovations over unknown adhesives, old patching or moisture-sensitive slabs carry more discovery risk.
Separate risks
It is often clearer to carry specific allowances for known uncertainties and a smaller general contingency than one large unexplained percentage.
Update the budget
As testing and investigation reduce uncertainty, convert allowances into contractor scope rather than leaving them as permanent padding.
Commercial flooring decisions depend on the actual substrate, moisture conditions, traffic, cleaning regime, accessibility requirements, fire/building rules, manufacturer instructions and local code. This site is for planning and comparison, not installation instructions.