3. Slope & Drainage

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Ideally, a tennis court should be a flat surface lying in a single horizontal plane. However in

Ireland due to the prevalence of rain it should be sloped to assist in the run off of rain. Where the court is sloped for drainage the single plane of the surface should always be maintained.

The gradient for non-porous courts shall be min. 1:120 and max 1:100. Porous courts should be laid to a maximum gradient of 1:120 and a minimum of 1:200. Porous court may be laid flat if a gradient is incorporated in the sub-surface. Where a porous surface or subsurface is being used great care should be exercised to ensure the porosity or ability to drain is maintained. In the case of a new surface the contractor should be requested to demonstrate the porosity and in the case of old sub-surfaces the surface should be cleaned (hosed clean with water to try and open the surface and make it more porous. The surface drainage ability can be tested simply by pouring water onto the surface. If the surface is porous and the drainage is working then the water should disappear in 1-2 minutes. Some contractors will offer to drill holes in a subsurface but this will only give a marginal improvement and really does not solve poor drainage.

The slope should be oriented to minimise its effect on play. Thus, where a court must be sloped for drainage, a slope from side-to-side is preferred (see figure).

The slope is determined by measuring the ratio of change in elevation to horizontal distance.

Preferred orientation of slope (side-to-side), if necessary.

slope image


Test apparatus consists of:

  • A distance-measuring device, calibrated to ± 0.05%, such as a laser distance meter or a steel tape.
  • A surveyor’s level with a measuring staff. This may be either a laser level, which sweeps out a horizontal plane with a beam of visible or infrared light, or an optical level, where the plane is defined by the horizontal axis of the instrument.

A surveyor’s level may be checked using the standard ‘two-peg’ method, which gives an absolute measurement of the accuracy of the level. If the two-peg test reveals any error, the level must be serviced or repaired, as necessary.