A self propelled laser guided screed can routinely create fl numbers of about 35 and higher.
Ff 35 floor flatness.
F f 25 f l 20 moderately flat.
Concrete strengths rebar average rebar weights welded wire mesh pan slabs slab flatness and f numbers.
Minimum subfloor flatness using astm e1155 ff sof f or a 10 3m.
Ff fl numbers have the following floor flatness classifications.
Ff25 fl20 moderately flat ff35.
F f and f l tolerances shall be tested in accordance with astm e 1155.
Floor flatness variation from surface plane bumpiness f l floor levelness variation from horizontal plane pitch.
They describe a concrete slab s flatness ff and.
F numbers provide architects and contractors a method of determining the flatness and levelness of a concrete floor slab.
Flatness is a measure of how bumpy the floor s finished surface is.
Concrete slab flatness slab flatness the degree of a slab s flatness is expressed by two numbers the ff and the fl together these are the f numbers they are the face floor profile numbers developed by allen face from 1978 to 1987.
F f this number is used to indicate the flatness of a random traffic floor.
The f f value is primarily a result of how good the finisher was at working the.
Actual overall f numbers shall be calculated using.
F f is measured as the curvature of the floor over a 2 foot interval.
F l specified overall value 25 minimum local value 18 c.
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.
To quantify floor flatness using f numbers you begin by measuring the elevation differences d between points on the floor that are 1 foot apart along a straight line.
F f f l numbers have the following floor flatness classifications.
Take a grid of 2 foot intervals over the entire floor and put the values through an equation and you get the f f value as an indication of the waviness of the floor.
What does a specification for a floor flatness of 1 8 inch in 10 feet equal in f numbers.
However it also advises that the selection of the proper ff fl tolerances for a new project is best made by measurement of a similar satisfactory existing floor.
They are calculated using the standards set forth in astm e1155 which is the standard test method for determining f f floor flatness and f l floor levelness numbers the american concrete institute indicates acceptable ranges for flatness and levelness in aci 302 1 guide.
A self propelled laser guided screed can routinely create f l numbers of about 35 and higher.
