CONCRETE CONSTRUCTION has devoted many pages of editorial to floor flatness over the years, and for good reason. If a contractor delivers a floor that does not meet the specified flatness, chances are good he will end up in court, possibly spending thousands of dollars on litigation, which could put his business in jeopardy. On the flip side, a successful floor contractor that meets the floor specifications can find his business growing rapidly.
However, man does not achieve flatter floors alone.
In an effort to guarantee that contractors deliver flatter floors, two national flooring associations, the National Wood Flooring Association, Chesterfield, Mo., and the Flooring Contractors Association, West Bloomfield, Mich., jointly endorsed Position Statement #6, “Division 3 versus Division 9 Floor Flatness Tolerances,” written by the American Society of Concrete Contractors, St. Louis. In a prebid meeting, this Position Statement can be introduced to address changes that will occur in a concrete slab between the pouring and the time when the floor covering is applied.
According to the Position Statement, concrete contractors (recognized as Division 3) and flooring contractors (Division 9) measure floor flatness differently. Additionally, floor flatness changes over time due to curling. Because of its unpredictable nature, curling makes it almost impossible to determine what the flatness of a slab may be once it is time to install the floor coverings.
What are the differences between Division 3 and Division 9 specifications?
Division 3 specifications for concrete floor flatness include FF requirements and tolerance measurements based on ASTM E 1155-96, “Standard Test Method for Determining FF Floor Flatness and FL Floor Levelness Numbers.” Division 9 specifications for concrete floors set to receive a floor covering, typically provide FF requirements in terms of allowable gap under an unleveled straightedge. There is no ASTM procedure for this measurement.
This joint Position Statement finds the concrete contractors and flooring contractors as allies, both seeking a common solution to a problem that has cost both parties countless dollars in rework. In the past, concrete and flooring contractors were often at odds due to the incompatibility of floor flatness tolerances.
The concrete and flooring contractors agreed that it is necessary for the floor owner to provide a bid allowance, established by the designer and based upon the floor coverage requirements. This allowance would be used for the grinding and patching necessary to close the gap between Division 3 and Division 9 tolerances. Any unused allowance money returns to the owner.
If you are interested in learning more about the Position Statement, visit www.ascconline.org.