Ff/Fl - Stay flat and level. Stay compliant and efficient.
A quick look around your concrete flooring surface may be all it takes to know your slabs aren’t flat and level. But to know by how much—and whether they’re out of compliance—takes more than a glance. It requires precision measurement performed by expert technicians.
Durable Surfaces measures floor flatness (FF) and floor levelness (FL) for random traffic areas. (For defined traffic areas, such as a Very Narrow Aisle (VNA), we test Fmin). Once testing is complete, we determine how out of tolerance your slabs are and how best to repair, restore and remediate them. Using spot grinding, milling and polishing, we’ll make sure you achieve your target numbers.
Floor Flatness/Floor Levelness (FF/FL) – used to define the Flatness and Levelness of a concrete slab. This measurement usually takes place in random traffic areas.
The acceptable ranges for flatness and levelness are defined in the ACI 302.1, Guide for Concrete Floor and Slab Construction. And the calculations using the standard test method, are defined in the ASTM E1155, Standard Test Method for Determining FF Floor Flatness and FL Floor Levelness number.
The measurements are taken every foot, in multiple perpendicular directions, and must be taken within 72 hours of concrete placement to be certified. Though, the recommendation is immediately after slab has been mechanically finished.
There is an established formula that determines the number of data points and runs needed to provide a certified result for a slab. Each slab pour is considered a localized FF/FL area which is the Minimum Local Value. This number is often lower than the Specified Overall Value to allow for margin of error. Specified Overall Values are the aggregate average of the entire slab.