Finished Concrete Floor Flatness

Floor flatness and levelness testing the complete.

Finished concrete floor flatness. 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. Both numbers are dimensionless and the higher the number the more accurate the floor construction. Tom klemens the dipstick tool is the typical measurement taken for flatness the morning after concrete is placed. Ff flatness is most affected by the finishing operation.

Due to concrete shrinkage and slab curling ff fl numbers diminish with time. 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. This was measured by laying a 10 foot straightedge on the finished floor and measuring the greatest gap below the straightedge. This applies to floors that will receive finishes such as wood quarry tile carpet or sheet vinyl products.

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 levelness one of the things that distinguishes a high tolerance floor is its f number requirement. The higher the f number the flatter or more level the floor. F numbers were developed in the 1980s to provide a systematic quantitative way to indicate the flatness and levelness of a concrete floor.

This method worked quite well for decades. Aci staff 2008 concrete q a. The ffnumber relates to the rate of change of the elevation of a concrete floor over a 12 interval. 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.

Specifically joints and cracks curl making the floor less flat with the passage of time. Material tolerances are in section 2 including the location tolerance for reinforcing bars which varies depending on the thickness of the concrete member. The fallacy of the straightedge method was the location of the measurement. For the concrete contractor flatness is specified as an ff number and levelness as an fl number.

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. Fl levelness is most affected by forming and strike off.