Concrete Slab Finishes and the Use of F-number System

Matthew Stuart, P.E., S.E., F.ASCE

Course Outline

The F-number system is used today to specify and evaluate the levelness and flatness of both slab-on-grades and elevated slabs. This one hour online course covers a basic understanding of the need for and the derivation of the F-number system used to specify and determine slab levelness and flatness.

This course includes a multiple choice quiz at the end.

Learning Objective

At the conclusion of this course, the student will:

• Develop an understanding of the F-number system;
• Understand the association between recommended F-numbers and floor profile designations; and
• Both understand and develop project specifications used to establish and control concrete floor slab levelness and flatness during construction.

Course Introduction

Because of the inherent inadequacies of the straightedge specifications historically used in the construction industry a new system to control concrete floor slab flatness and levelness was developed. The new method was made possible through the development of equipment that was able to accurately and systematically quantify the levelness and roughness of slabs. ACI Committee 117 in turn established a system to evaluate the data from the testing equipment. This method is referred to as the Face Floor Profile Numbers or F-number system and is used today to specify and evaluate the levelness and flatness of both slab-on-grade and elevated concrete slab construction.

Course Content

The course content is contained in the following PDF file:

If you have trouble reading any of the material on line, it is recommended that the course material be printed out for better resolution.

Course Summary

The F-number system established by ACI 117 should be used in lieu of the old straightedge specification for the construction of concrete floor slabs. Two distinct and separate F-numbers are used for specifying floor flatness (roughness) and levelness (tilt or slope) for slabs subject to either random or defined traffic patterns.  ASTM E 1155 is the industry standard for testing of random traffic floors. The ASTM E 1486 test procedure can be used to determine the Waviness Index for either random or defined traffic floor slabs. F-numbers are measured in the field typically using either a Dipstick (for random traffic floors) or a profilometers (for defined traffic floors). Project specifications should provide for a remedy for out-of-tolerance floor slabs.

Effective F-Number Specification by Allen Face, FACI, President, Allen Face & Associates. Reprint courtesy of L&M Construction Chemicals Concrete News Winter 2005 (Volume 5, Number 2).