Finished Concrete Floor Flatness

F numbers were developed in the 1980s to provide a systematic quantitative way to indicate the flatness and levelness of a concrete floor.

Finished concrete floor flatness.

Specifically joints and cracks curl making the floor less flat with the passage of time. Due to concrete shrinkage and slab curling ff fl numbers diminish with time. Material tolerances are in section 2 including the location tolerance for reinforcing bars which varies depending on the thickness of the concrete member. Concrete contractor pours the concrete and finishes it to the specified floor flatness requirement as stated in aci 117 specification for tolerances for concrete construction and materials the f.

Both numbers are dimensionless and the higher the number the more accurate the floor construction. This method worked quite well for decades. Ff flatness is most affected by the finishing operation. 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 and levelness testing the complete. Rejecting floors based on one sample measurement line concrete international jul pp. 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. Fl levelness is most affected by forming and strike off.

The fallacy of the straightedge method was the location of the measurement. This was measured by laying a 10 foot straightedge on the finished floor and measuring the greatest gap below the straightedge. Tom klemens the dipstick tool is the typical measurement taken for flatness the morning after concrete is placed. For the concrete contractor flatness is specified as an ff number and levelness as an fl number.

Floor flatness levelness one of the things that distinguishes a high tolerance floor is its f number requirement. 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. The higher the f number the flatter or more level the floor. This applies to floors that will receive finishes such as wood quarry tile carpet or sheet vinyl products.

American concrete institute aci 301 16 specifications for structural concrete. Aci staff 2008 concrete q a.