BIRDBATHS
Birdbaths
"Birdbath" is a term commonly used in the tennis industry to describe a low area on a court that holds water. More precisely, the American Sports Builders Association (ASBA) defines a birdbath as any area where standing water more than 1/16” (2mm) (commonly measured using a nickel) remains after drainage of the area has ceased or after one hour of drying at 70 degrees Fahrenheit in sunlight. Birdbaths delay play on the court after rain and may cause staining and/or peeling of the surface.
Among the causes of birdbaths are:
Unsuitable material in the subsoil;
Inadequate drainage around the tennis court;
Improper slope or grade;
Inadequate compaction of the subgrade; or
Paving error.
Paving and surfacing, even with laser-guided equipment, involves both skill and judgment. The number of variables impacting the paving and surfacing processes makes it unreasonable to expect perfection. Minor depressions in the surface, those less than 1/16” deep or those that drain or dry in under an hour, are considered within tolerance and are acceptable. In a new or recently resurfaced court, however, the contractor should correct birdbaths.
Because site selection, design and construction can involve compromise, over time, even properly designed and constructed courts may develop birdbaths over time. During design and construction, a proper balance must be struck between the risk of some problems over the long term versus the cost of extensive remediation prior to construction. Courts sometimes are built on sites which are reclaimed or which have been deemed unsuitable for other purposes. In such cases, less than ideal subsoil, grade or drainage conditions may exist. Additionally, over time, new circumstances may arise which lead to settling or drainage problems.
The owner's expectations regarding repair of birdbaths should be based on the nature of the birdbaths that exist to be repaired and the amount of money budgeted for the repair. For example, the owner should understand that birdbaths created by improper compaction or unsuitable materials may reappear later due to further settlement, while repairs to birdbaths caused by improper slope or grade may only move the water to a different area on the court.
Owners also should understand that available repair methods and materials are imperfect. Asphalt resurfacers and acrylic patch binders are water-based materials. After they are installed flush with the surface, they may shrink due to dehydration, allowing the area to once again hold water. Asphalt patches and acrylic repairs require time and proper weather conditions to cure. Further, patching materials can be installed only to an effective depth of approximately 1/2”. For these reasons, even a skilled contractor may make several site trips to "fine tune" a repair. Complete removal of standing water may be impossible. Generally, the owner should accept that repair of birdbaths is only a means of reducing the inconvenience they cause and extending the useful life of the court.
The number, size and depth of birdbaths is another consideration. The existence of multiple birdbaths or major depressions of 1/2” or more may indicate more serious problems. Repairing multiple or deeper birdbaths is labor intensive and often results in cosmetic imperfections, which may require resurfacing to correct. The larger the birdbath, the more difficult it can be to repair. Prior to repairing numerous birdbaths or major depressions, the owner should discuss the cost and alternatives, such as installing an overlay. In some cases, only reconstruction will provide a long-term solution.
Differences in site, weather and soil conditions require variations in construction and repair methods and materials. Readers are advised to consult a qualified contractor or design professional before undertaking construction or repair of a court.
