Waste is where flooring estimates quietly go wrong in both directions. Too little and your crew runs short mid-install; too much and your bid carries material the job never needed. The fix is calculating waste by material and pattern, not by habit.
Broadloom carpet with a pattern repeat behaves nothing like 24×24 carpet tile. Plank direction changes LVT waste from room to room. Sheet vinyl in a healthcare corridor with welded seams and flash cove needs a very different factor than the same product in an open retail floor.
Room geometry matters as much as material. Long narrow corridors, angled walls and small chopped-up rooms all push waste up in ways a flat percentage never captures. A good takeoff calculates cuts against actual room dimensions.
As a rule of thumb: modular tile in open areas runs lean, patterned broadloom and diagonal layouts run heavy, and anything with seam-welding or coving deserves its own line. When in doubt, calculate — do not assume.