Proper methods of setting and measuring concrete floor construction tolerances are important to owners, vehicle manufacturers, and designers, as well as to floor contractors. When these groups have a realistic understanding of floor tolerances, they can specify flatness in the most cost-effective way.

AVAILABLE METHODS AND EQUIPMENT

The traditional method of specifying floor flatness often led to arguments over interpretation and enforcement. As a result, the ASTM E 1155-87 method using F-numbers was developed several years ago. More recently, ASTM has standardized another method (E 1486-94) called the Waviness Index.

SELECTING A PROPER FLATNESS TOLERANCE

Floor flatness can generally be classified within the following types: superflat; very flat; flat; moderately flat; and conventional. To be practical for specifying floor surfaces, these terms must be defined and magnitudes of allowable deviation established, either in the specifications or by established industry standards.

COMPARING TOLERANCE METHODS

How well do the random-traffic tolerancing methods work? How do they compare to one another? An extensive study was undertaken to answer these questions. A significant number of pairs of lines were rated essentially equally flat by their F-numbers but substantially different from one another by both straightedge and Waviness Index analysis. Based on the results of this study, Waviness Index seems best to evaluate the suitability of floor surfaces for foot and forklift traffic.