Normal floor placing and finishing practices leave some variations in the finished surface in the form of small bump and dip waves. The location, length, and amplitude of these waves are determined in part by the construction methods and equipment used. A floor contractor can use flatness measurements taken during construction to fine-tune placing and finishing methods for better compliance with the owner's flatness requirements.

WAVINESS INDEX BASED ON MULTIPLE CHORD LENGTHS

Floor flatness is best ensured by specifying and using the Waviness Index tolerancing method as defined by ASTM E 1486. The Waviness Index is calculated using the same data used to calculate F-numbers. It is a measure of deviations from the midpoints of imaginary chords as a computer moves the chords along a floor-elevation profile survey line.