With the wealth of theoretical and practical information available today, every contractor should be able to produce, economically, a thoroughly efficient floor in full accordance with a client's wishes. Essentially, performance is governed by three aspects: good design, correct choice of concrete mix, and , above all, proper finishing techniques. In this article, we shall summarize the available knowledge vital to the construction of a modern concrete floor. The structural requirements for a concrete floor must comply with the local building code. The required thickness will depend on: the nature and frequency of superimposed loads; the strength and quality of the concrete to be used, and the supporting power and uniformity of the subgrade. If any of these factors are disregarded, the resulting floor will be uneconomical to place. If overdesigned, even though the floor will give good service, the initial cost will be excessive. If under designed, the floor will be short-lived or costly to maintain. Corners are the critical points in floor slabs of uniform thickness. Though edges are somewhat less critical, stresses at these points are substantially greater than at the center of the slab. With wheeled traffic, it is then essential to ensure that a load is transferred across joints evenly and that there are no free cantilevered edges on which concentrated loads can be exerted. The problem is especially serious where there is heavy traffic and in situations where excessive shrinkage occurs. Site preparation is also important. A well-drained subgrade is essential. Ideally a floor should be above the external finished grade level and above the highest level of the water table. Perimeter drains laid close to the walls of the building will remove water before it can penetrate the subsoil. Greater attention must be paid to drainage with soils subject to volume change with varying moisture content than with free draining granular materials such as gravels and coarse sands.