Most experts consider concrete the ideal material for a tennis court. Aside from the periodic repainting of the playing lines, a reinforced concrete court require little maintenance. Above all the true, even surface assures a consistency accurate bounce of the ball. A well constructed tennis court begins with the subgrade. It must be thoroughly and uniformly compacted and free from soft, spongy areas or deleterious materials. It is general practice to lay two concrete slabs 4 inches thick, separated by an expansion joint placed under the net. The expansion joint should be 1 inch thick, and a similar joint should be placed between courts if they are constructed side by side. Reinforcement may be either wire mesh or reinforcing bars.