Ff 35 Floor Flatness

F l specified overall value 25 minimum local value 18 c.

Ff 35 floor flatness. They describe a concrete slab s flatness ff and. Floor flatness variation from surface plane bumpiness f l floor levelness variation from horizontal plane pitch. 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. F numbers provide architects and contractors a method of determining the flatness and levelness of a concrete floor slab.

A self propelled laser guided screed can routinely create fl numbers of about 35 and higher. Flatness is a measure of how bumpy the floor s finished surface is. What does a specification for a floor flatness of 1 8 inch in 10 feet equal in f numbers. 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.

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. Flat 35 25 very flat 45 35. F f 25 f l 20 moderately flat. Concrete strengths rebar average rebar weights welded wire mesh pan slabs slab flatness and f numbers.

F f is measured as the curvature of the floor over a 2 foot interval. F f this number is used to indicate the flatness of a random traffic floor. F f specified overall value 35 minimum local value 24 floor levelness number. 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.

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. Minimum subfloor flatness using astm e1155 ff sof f or a 10 3m. F f f l numbers have the following floor flatness classifications. It recommends that slabs to receive thin set flooring with moderate or heavy traffic have composite flatness and levelness of ff 35 fl 25.

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. The f f value is primarily a result of how good the finisher was at working the. Ff25 fl20 moderately flat ff35. F f and f l tolerances shall be tested in accordance with astm e 1155.