Concrete Floor Flatness And Levelness

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Concrete floor flatness and levelness. Concrete floor slab flatness and levelness traditionally allowable tolerances of concrete floor slabs were determined by checking the slab surface with a 10 foot straightedge. History of concrete floor flatness and floor levelness traditionally concrete floors were specified to have a deviation of less than 1 8 over 10 feet. Floor flatness levelnessone of the things that distinguishes a high tolerance floor is its f number requirement.

What does a specification for a floor flatness of 1 8 inch in 10 feet equal in f numbers. Common tolerances were 1 8 inch or 1 4 inch in 10 feet. There is a difference between the two.

The number system and the measuring method were the basis for astm e1155 standard test method for determining ff floor flatness and fl floor levelness numbers which was developed in collaboration. For concrete slabs receiving resilient floor covering therefore it is most important to describe limits of floor flatness. In practice ff and fl values generally fall between 12 and 45.

When explaining this to my customers i often use a pool table as an example. Although there are no direct equivalents between f numbers and straightedge tolerances aci 302 construction of concrete floors and slabs gives the following table of approximate values. The scale is linear so that relative flatness levelness of two different floors will be in proportion to the ratio of their f numbers.

F numbers were developed in the 1980s to provide a systematic quantitative way to indicate the flatness and levelness of a concrete floor. The higher the f number the flatter or more level the floor. This was measured by laying a 10 foot straightedge on the finished floor and measuring the greatest gap below the straightedge.

Floor flatness f f controls the bumpiness of the floor surface and is primarily affected by the finishing operations after screeding including restraightening and power floating. Aci 117 begins by defining what the tolerances mean in terms of such things as bowing deviation flatness and levelness and provides drawings to help explain these terms. This method worked quite well for decades.