Finished Concrete Floor Flatness

Ff flatness is most affected by the finishing operation.

Finished concrete floor flatness.

Material tolerances are in section 2 including the location tolerance for reinforcing bars which varies depending on the thickness of the concrete member. The ffnumber relates to the rate of change of the elevation of a concrete floor over a 12 interval. Specifically joints and cracks curl making the floor less flat with the passage of time. Aci staff 2008 concrete q a.

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. Floor flatness and levelness testing the complete. Floor flatness levelness one of the things that distinguishes a high tolerance floor is its f number requirement. The fallacy of the straightedge method was the location of the measurement.

This method worked quite well for decades. This was measured by laying a 10 foot straightedge on the finished floor and measuring the greatest gap below the straightedge. For the concrete contractor flatness is specified as an ff number and levelness as an fl number. F numbers were developed in the 1980s to provide a systematic quantitative way to indicate the flatness and levelness of a concrete floor.

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. 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. 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. Tom klemens the dipstick tool is the typical measurement taken for flatness the morning after concrete is placed.

Due to concrete shrinkage and slab curling ff fl numbers diminish with time. American concrete institute aci 301 16 specifications for structural concrete. This applies to floors that will receive finishes such as wood quarry tile carpet or sheet vinyl products. Rejecting floors based on one sample measurement line concrete international jul pp.

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.