How Flat is Your Floor? Let’s Talk High-Rise in DTLA

Fenagh is currently working on an exciting high-rise development at 5th and Olive in the heart of Downtown Los Angeles with our coast to coast trade partner Suffolk Construction. As each level of the building is constructed, one of our field engineers is responsible for ensuring the quality of slab flatness and levelness. Last week we were onsite to record slab readings 22 stories above Pershing Square.

For the testing, Senior Technician Edgar Robles was onsite to perform the FF/FL testing using a Dipstick device. In today’s age of technology there are many ways to record this data, in Fenagh’s case, we prefer the Dipstick method which is an older method but yields more accurate results versus its automated counterparts.

When performing the testing, he moved across the slab slowly and in a straight line as he took his readings. In order to remain straight, he will use string or reference points to guide him, since variations in his line will effect the end result. As he moves along the slab, it’s important to remove all debris from the line which will alter the results if not properly addressed.

Understanding Floor Flatness and Levelness

F-numbers provide architects and contractors a method of determining the flatness and levelness of a concrete floor slab. They are calculated using the standards set forth in ASTM E1155, which is the Standard Test Method for Determining FF Floor Flatness and FL Floor Levelness Numbers. FL numbers provide information about the concrete Floor Levelness. Levelness depicts how closely the finished floor matches the intended slope indicated in the design documents.

Elevation differences are measured every 10-feet within 72 hours after the concrete is placed and those measurements are entered into a calculation to determine floor levelness (FL). FF numbers depict the Floor Flatness, or how close to planar the floor is. In other words, Floor Flatness is a statistical measurement of how wavy or bumpy a concrete floor is and takes into account the amplitude (height of the waves) and the wavelength (horizontal distance between waves). Elevation differences are taken every foot within 72 hours after the concrete is placed and a formula determines the FF measurement. As with FL, the measurements are linear and higher numbers represent a flatter floor.

Have a project that requires Floor Flatness and Levelness? Fenagh is your service provider, call us today!

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