The class of local surface regularity of a directly finished base or levelling screed, if used, should be selected from those given in Table 5 according to the use of the floor. In making this selection, account should be taken of the type and thickness of the wearing screed or flooring to be applied and the standard of surface regularity required of the finished floor.
The highest standard (SR1) should be used where a thin flooring is to be applied and where the minimum irregularity is required of the finished floor, e.g. for a television studio. Conversely, the lowest standard (SR3) may be selected where a thicker type of wearing surface is applied and where the regularity of the finished floor is not a significant factor.