A floor is level or flat? Does it matter? Would you know?

Poor floor flatness and/or levelness could impact your build project with unwanted consequences. The levelness of the floor in a warehouse, for example, will limit how high pallets can be stacked. If you need to lay very large format tiles then the substandard flatness of the screed could cause massive headaches for the tilers with further maintenance problems down the line.

Irregularities in the sub-floor may cause waviness and sloping areas, which will affect drastically the quality of a construction project. Indicating deviations over short distances from a 2m straight edge laid flat on the floor, flatness (surface regularity) is most affected by finishing techniques. Levelness (departure from datum), on the other side, relates to measurements over long distances and is most influenced by the formwork setup.

Departure from Datum

A flat floor may not be level but could pass the Surface Regularity test

Different environments call for different flatness and levelness specifications. Whilst surface regularity classes are divided into SR1 (maximum deviation of 3mm), SR2 (maximum deviation of 5mm), and SR3 (maximum deviation of 10mm), deviations from datum level should not exceed ±15 mm to be satisfactory. Greater accuracy is required in projects involving thin flooring, such as wooden and tile flooring, in the vicinity of door openings, along walls, and in areas where a finer flatness and levelness tolerance is imperative (e.g. specialised industrial settings, hospitals, television studios, etc.).

Screed fails surface regularity test

A level floor will pass the departure from datum test, but will need to be tested for Surface Reguarity as well

In a construction project, the architect or the engineer must specify the maximum flatness and levelness deviation permitted. In some projects, a maximum flatness and levelness deviation of 10mm from a 2m straight edge and 15mm from datum, respectively, may be acceptable; in others, contractors must carry out a series of tests (e.g. laser level surveying and “straight edge” method) to deliver nearly perfectly flat and level substrates, with deviations that do not exceed 2 or 3mm.

Flat and level floors play a very important role in the overall serviceability of an area. With invaluable experience in screed systems and testing, BuilderScreed can offer comprehensive screeding solutions to companies operating throughout the South East England. Regardless of the industry sector, be it logistics, warehousing, manufacturing, or retail, we can help all our clients get a perfectly flat and level sub-floor for improved performance and productivity.

Professional advice is just a few clicks away
Our experts understand the issues most builders are facing right now, and have created a guide to help you gain an in-depth insight into the key screeding processes and technologies. Learn more and receive 6 further tips sent directly to your inbox.

BuilderScreed is a division on CSC Screeding Ltd