A whitepaper on how FF and FL measurements are used in constructions.
The F-Number system is a statistical method of evaluating horizontal concrete surfaces for
flatness and levelness. The Face Company, in conjunction with ACI Committee 117, developed
the basis for the system through the use of a patented continuous Profileograph machine. For a
typical random traffic industrial or other similar floor slab there are two F-Numbers used to
evaluate the floor flatness and levelness, FF and FL; respectively. FF (flatness) is most affected by
the finishing operation. FL (levelness) is most affected by forming and strike-off. Both numbers
are dimensionless and the higher the number the more accurate the floor construction.