The foundations or subsurface for tennis courts have a considerable bearing on the overall performance of the court. Great care has to exercised to ensure that when the final playing surface is installed that it is laid on a suitable subsurface – if the subsurface is wrong then the playing surface will never be right and this can lead to a lot of maintenance/remedial action with obvious disruption to play and costs/compensation claims. So it is fundamental that the subsurface is properly specified and installed with respect to drainage, slope and evenness
A porous asphalt tennis court surface or subsurface is made up of several layers of aggregate, often limestone, bound together with bitumen. Finer grades of aggregate are used closer to the top surface. The foundation provides support for the layers of porous asphalt and allows water to drain away from the surface of the court. If water is held in the sub-surface frost can cause the court to heave. Loosely packed stones will provide better drainage, but reduced stability.
Porous asphalt courts are typically laid by hand. Hot bituminous asphalt is raked between steel bars and then rolled to compact the aggregate. The steel bars are set using dual-plane, laser levels for accuracy. If there is a sufficiently stable formation or depth of foundation, laser-automated machines can be employed to lay the asphalt. The asphalt must be rolled immediately to compact the aggregate before the bitumen cools. Therefore, thicker layers, which take longer to cool, can be used to give higher densities. The wearing course (top layer) uses the finest grade of aggregate to achieve a dense, uniform surface.
For courts, which use asphalt as the playing surface during the opening season of play, hot weather may soften the bitumen and aggregate can be ‘plucked’ out of the wearing course. It is important that the court is not used under these conditions. Three weeks after laying, the bitumen has dried and hardened and the court can be painted. Pre-spraying the court with a polyurethane (PU) or acrylic (PMMA) binder extends the life of the surface and reduces stone plucking. PU or PMMA are also used within the paint. The colour coating is applied in at least two passes in opposite directions.
Please note that it is very important that where the subsurface is found to be uneven, it should not be levelled/patched using a different material than that of the subsurface - this may lead to different drainage patterns or to different bounces of the ball in different parts of the court.
Where asphalt is being used for the surface or subsurface great care should be exercised in selecting the contractor to carry out the works. They should be experienced in carrying out this work - this is further covered in the section on Contractors below. Note contractors who are experienced in laying car parks may not have the necessary experience for laying tennis courts, as the grades of asphalt are totally different due to their different loading and drainage requirements.
5.1 Sand filled grass carpet or asphalt court
5.2 Typical Construction Photos
The foundation layer, consisting of angular pieces of limestone.
Hand laying bituminous asphalt
Rolling the wearing course
Clockwise from top left: Wearing course, wearing course (as rolled), and base course