The construction method for a floor will significantly affect the success or otherwise of achieving the flatness and levelness specification, but the vital element is the skill of the labour used. In normal circumstances with very good workmanship only the long strip method will achieve the FM1 standard of surface regularity. Other construction techniques with their own intrinsic benefits can be used to achieve other flatness classification standards.
Joints
Users of floors are becoming increasingly aware of the many issues that need addressing when the design and detailing of a new floor are being considered. Joints are a major discussion area and sometimes the need to minimise or eliminate formed joints may be more important than a floor's flatness and levelness. This is particularly so in areas of intensively trafficked free movement, such as floors used by heavily loaded pallet trucks with small hard wheels. The use of post-tensioning or a steel fibre concrete design may also be considered as these can avoid the need for any joints. The choice of the construction method must take into account the relevant factors, such as joints and the degree of flatness achievable, in order to decide on the method best suited for a particular project.
Construction techniques
many surveys of free movement areas of floors by specialist survey firms have found that most of those constructed using Laser Screed large area pour systems achieved compliance with FM 2, Property IV column B, in over 98% of the overall area surveyed. It is unfortunate therefore, but not unexpected, that where a free movement area surface did not quite fully satisfy the required tolerances, the owner or user has sometimes insisted on remedial work to correct even extremely small defects. Such corrections are probably unnecessary as the defects are unlikely to adversely affect the operations on the floor under free movement traffic. The end user needs to be informed of the expected compliance of each construction method and then make a judgement of the method to use based upon his surface regularity needs.
Adding a dry shake finish during construction is likely to make the FM limits more difficult to achieve. Dry shake finishes applied by machine are less likely to affect the surface tolerances achieved. Where a coloured dry shake finish is to be specified, the specifier should be aware of the need to use a construction technique and flooring contractor with a good track record in achieving surface regularity tolerances. Grinding a coloured finish to correct flatness errors can cause colour differences which may be unacceptable to the end user.