Floor Flatness and Levelness Testing: ASTM E1155 Standards and Procedures

Floor flatness and levelness testing is critical for concrete construction quality, determining whether your concrete floors meet specification requirements. Too often, concrete testing focuses only on the plastic state and 28-day breaks. Testing for air, slump, temperature, and casting cylinders is just the start.

Depending on your application, additional concrete testing is needed for project success. Placed concrete isn't only part of the structure but also the foundation for other trades to make the space habitable. Floor flatness and levelness testing are two of the critical measurements needed for project success.

What is Floor Flatness and Floor Levelness Testing?

Floor flatness testing determines both Floor Flatness (FF) and Floor Levelness (FL) values in general accordance with ASTM E1155. This standard for flatness testing has been around since the early 1980s and has gone through many modifications over the years. ASTM E 1155 establishes the methodology for measuring and reporting these critical concrete floor surface characteristics.

During the last three decades of the previous century, these values were measured using a 10-foot straight edge across the concrete surface. Repeatability of the test became a point of contention. As construction equipment and technologies progressed, construction precision increased and lessons were learned. More accurate measurements were needed, which led to the development of modern floor flatness testing equipment and refined ASTM 1155 procedures.

Understanding Floor Flatness vs. Floor Levelness

What is Floor Flatness (FF)?

Floor flatness is based on a statistical analysis of slope changes along a specified distance. The slope changes are calculated every 12 inches. In today's market there are pieces of equipment capable of reading the slope changes every inch or so. Essentially, FF is the "bumpiness" measurement along the concrete surface. Think about it as the number to determine if you will spill your coffee in the morning if you were to drive on it. The scale of measurement is fairly linear and typically ranges from 0 to 100. Higher FF numbers indicate flatter floors.

What is Floor Levelness (FL)?

Floor Levelness, although the determination of the values is calculated in a similar manner, this value relates more to the slope or inclination of the concrete surface. This value is critical in slabs-on-grade. For elevated slabs, the FL values could be deceiving as elevated slabs could be sloped in one or more directions.

Additionally, elevated slabs could experience small deformations depending on the support type, during the hardening/curing process of the concrete. Post-tensioned slabs will show different FL behavior than a slab on a metal deck or a lightweight concrete slab. Understanding levelness is just as important as flatness testing for overall floor quality.

ASTM E1155 Standard Requirements and Compliance

ASTM E1155 establishes the testing protocol for floor flatness and levelness testing. The standard, also referred to as ASTM E 1155 or ASTM E1155, specifies how measurements should be taken, calculated, and reported. Compliance with ASTM 1155 is typically required by project specifications.

Critical Timing and Compliance Requirements

FF and FL numbers are important for the concrete structure quality, acceptance and future use. The FF and FL values must be taken within 72 hours of the concrete placement. Coordination between the concrete contractor and the testing laboratory is critical for compliance with ASTM E1155.

Omnant provides the contractor with the flexibility of remotely scheduling floor flatness testing with the laboratory to measure both FF and FL values. Both values vary on a scale of 0 to 100. Typical FF and FL numbers depending on the application are tabulated in ACI 302.

Why Floor Flatness and Levelness Matter

The FF and FL of the floor is important for user comfort, proper drainage, and critical for flooring contractors. Carpet, tile, and other floor covering installers rely on the FF and FL numbers to install flooring materials properly.

Can you imagine skating for the Stanley Cup (NHL) on bumpy ice? Or trying to get a 3-point shot to win the Larry O'Brien Trophy (NBA) on a tilted court? Just like athletes need consistent playing surfaces, your construction projects need reliable, flat floors to function properly.

Modern Applications Requiring Flatness Testing

As technology has evolved, the use of structures has changed considerably over the last decade. Many warehouses are automated these days. Automated equipment requires, in some cases, superflat floors. These measurements are an area of development in the current standards and our industry partners continue to work together to establish the boundaries and requirements for this type of construction materials testing.

Floor levelness and flatness specifications are becoming more stringent as automated material handling systems, robotic equipment, and precision manufacturing operations become more common. What was acceptable floor flatness 20 years ago may not meet today's requirements for advanced logistics facilities and high-tech manufacturing spaces.

How Omnant Simplifies FF/FL Testing

Modern floor flatness and levelness testing uses specialized equipment that measures elevation changes at precise intervals across the concrete surface. This equipment must be properly calibrated and maintained to ensure accurate FF and FL readings that comply with ASTM E1155 requirements.

Currently, our Omnant users benefit from our easy-to-use platform to keep track of the equipment's calibrations, maintenance, and usage. Since these are very precise measurements, it requires precise, calibrated, and well-maintained equipment.

These tests also need patience and a very strong neck! Some manufacturers provide their own reporting tool as part of the equipment purchase, and Omnant is able to integrate custom forms of reporting to meet your clients' needs. Omnant simplifies the process from an easy scheduling to ensuring the equipment is ready to provide 24/7 access to the reports.

Regardless of your project complexity, Omnant is here to make sure your testing operations are accurate, precise, consistent, reliable, and profitable. Schedule a free Omnant demo today!