A.S.B.A. Guidelines for Tennis Court Construction

2.Q. – Maintenance and Repair of Asphalt Tennis Courts

1.0 Introduction
This guide for the repair and maintenance of asphalt tennis courts has been prepared to provide the tennis court owner with information on court conditions that may develop and with recommended procedures for periodic maintenance and repair of asphalt courts.

The actual conditions on a court that require repair may vary somewhat from the illustrations provided here, so it is important to use this only as a general guide, and consult with a tennis court builder, engineer or materials manufacturer for their recommendation on repair of your particular court. 

2.0 General Requirements
A. Scope of Work to be Done
The repair work to be performed should include furnishing all the required labor, materials, equipment, implements, parts and supplies necessary for and pertinent to the work to be done. The products and procedures should be as recommended by the tennis court contractor and the manufacturer of the material used in the repair work. Prior to starting the work, the court owner and the contractor should have a written description of the present condition of the court, as well as the end result of the repair work expected by the owner.

Regular housekeeping maintenance performed by the owner should follow the suggestions outlined in Section 5.0.

B. Standards
The repair work should be done in a thorough and workmanlike manner and should conform to the standards for tennis court construction as prescribed by the U.S. Tennis Court and Track Builders Association.
3.0 Repair Conditions
A. Drainage – Subsurface
Improper perimeter drainage can cause excessive subsoil expansion that results in greater damage to the surface from freeze/thaw action and can, in turn, cause the surface to heave and create “birdbaths”. Also, this condition can cause loss of color and permit dirt and silt to wash onto the surface. By lowering the elevation of perimeter drainage swales, and consequently lowering the water table, this condition is improved or corrected. If a wet-weather spring is encountered, a subsurface perimeter drainage system, such as a perforated pipe in stone aggregate, is advisable. Consult with a local civil or soils engineer for specific advice.
B. Cracking
Cracking conditions may occur either in the base or on the surface of an asphalt tennis court. Cracking may stem from construction or job-site conditions such as improper slope of the courts, inadequate drainage of the site, base movement or poor compaction of the subbase.

Where any of these situations are present, major reconstruction of the courts may be required instead of repair.

1. Alligatoring
Alligator cracking most often occurs in the surface treatment applied over asphalt pavement. It is a readily identified pattern of interconnected cracks will vary from a faint surface pattern to full depth cracks and loose particles of the surfacing material.

Possible Method of Repair: Repairs may be made to this type of cracking with surface treatment coatings or with a combination of fiberglass membrane and surface treatment coatings. Depending upon the severity of the cracking, it may be necessary to resurface the court incorporating various methods such as geotextile membranes, stone slip-sheet, or installation of a modular or premanufactured surface system. Consulting a qualified contractor may help refine your direction or need.

2. Ravelling
Ravelling or spalling is the progressive loss of material in the surface of the asphalt or concrete slab, usually caused by weathering or traffic abrasion on courts with no surface treatment.

Possible Method of Repair: This condition may be corrected with the use of surface treatment coatings or an overlay of asphalt mix, followed by surface treatment coatings, depending on the severity of the condition. It may be necessary to resurface the court incorporating various methods such as geotextile membranes, stone slip-sheet, or installation of a modular or pre-manufactured surface system.

3. Reflection Cracks
Reflection cracks occur in asphalt, asphalt emulsion, or surface overlays. These cracks reflect a crack pattern in the pavement structure underneath. Reflection cracks are caused by vertical or horizontal movements in the pavement beneath the overlay resulting from temperature fluctuations and/or earth movements.

If reflection cracks occur in an asphalt overlay on a concrete slab, the cracks frequently follow the construction joints of the original slab.

Possible Method of Repair: Depending upon the severity of the cracking, it may be necessary to resurface the court incorporating various methods such as geotextile membranes, stone slip-sheet, or installation of a modular or premanufactured surface systems. Consulting a qualified contractor may help refine your direction or need.

4. Shrinkage Cracks
Shrinkage cracks are a random pattern of interconnected cracks, usually forming irregular angles and sharp corners. Often it is difficult to determine whether shrinkage cracks are caused by volume change in the asphalt mix or in the base or in the subgrade. This volume change can be better controlled by use of proper materials. Asphalt materials will be placed under stress with the addition of surface coatings. As the asphalt ages, it will shrink, causing additional stress. It is important to follow the Guidelines for the surface course of asphalt to minimize a future problem with shrinkage.

Possible Method of Repair: Depending upon the severity of the cracking, it may be necessary to resurface the court incorporating various methods such as geotextile membranes, stone slip-sheet, or installation of a modular or premanufactured surface system. Consulting a qualified contractor may help refine your direction or need.

5. Structural Cracks
This condition is usually due to failure of the subbase or improper mix design of the asphalt.

Possible Method of Repair: Depending on the severity of the cracks and a review of the site conditions, the remedy may incorporate various methods such as geotextile membranes, stone slip-sheet, or reconstruction of the court subbase. Consulting a qualified contractor may help refine your direction and minimize your cost.

6. Upheaval or Depression (Movement of Subbase)
Upheavals or depressions are the localized displacements of pavement due to changes in the subgrade or some portion of the pavement structure. Upheavals are most commonly caused by frost expansion in the granular courses beneath the pavement or in the subgrade. Upheavals may also be caused by the effect of moisture on expansive soils. This type failure is usually due to improper drainage below and/or around the court area.

Major depressions are often caused by decaying organic matter below the subbase or improper compaction of the subbase.

Possible Method of Repair: Reconstruction of the court is usually required to remedy this condition. Consulting an engineer or qualified contractor may help refine your approach and minimize your costs.

7. Hair-line Cracks
Hair-line cracks are of variable lengths, usually prevalent over entire areas, and may be caused by a variety of factors such as foreign matter (leaves, worms, clay) improper mix design, solvent type coatings and improper seal coats. They may develop into more significant types of cracks, i.e., alligator or structural, requiring more extensive maintenance.

Possible Method of Repair: Early repair with surface treatment coatings may remedy this condition. Consulting an engineer or qualified contractor may help refine your approach and minimize your cost.

8. Miscellaneous
a. Birdbaths
A “birdbath” is a minor depression in which water settles on a non-porous court surface after a rain or flooding. An accepted industry method of determining a birdbath is the flooding of courts, and waiting one (1) hour in minimum 70-degree Fahrenheit in sunlight. Then, if remaining water covers the thickness of a five cent piece (American coin), it can be considered a reparable birdbath. If the standing water does not cover a five cent piece, it is considered within tolerance and will evaporate within a reasonable amount of time.

Possible Method of Repair: Multiple applications of surface treatment coating may minimize or eliminate ponding.

b. Net Posts
Court repair problems as outlined in this Guideline often involve net posts and net post footing failure. Because the problems of net post failure vary significantly in degree, you should consult an engineer or qualified contractor to determine the proper course of action for repair.
4.0 Methods of Repair
A. Hot Asphalt Overlay Method
This is a method of placing 1″ or more of hot plant mix asphalt over an existing asphalt tennis court. Recommendations of the U.S. Tennis Court and Track Builders Association Section II.I., Hot Plant Mix Asphalt Tennis Courts, should be followed for gradation of the mix.

The overlay system can be successfully done over a court that has minor faults. The overlay system may not prevent the reappearance of major cracks in the slab beneath.

To improve adhesion of the overlay to the existing slab, a tack coat or bond coat of emulsified asphalt should be used prior to the overlayment.

B. Full Depth Repair
In any patching, the area requiring a patch should be cleared of all loose material, dust and dirt. Any defective materials should be removed to the full depth of the defect. If the defect is in the asphaltic courses but is caused by a failure of the underlying base course, the defective base course material should also be removed. If it is necessary to replace base course material, it should be ascertained that the subgrade condition is as it should be prior to replacing any base course. If the subgrade requires attention, it should be brought up to specification requirements prior to patching any of the asphaltic courses which the base course supports.

A tack coat must be applied to the bottom and sides of the patch and allowed to cure thoroughly.

If the defective material is old asphalt pavement, and the depth of the defective material and the subsequent repair will exceed 3/8″, hot plant mix asphalt may be used. The compacted lift should be brought to the elevation of the surrounding sound surface.

C. Asphalt Overlay
The overlay of asphalt should consist of a 1″ thick mixture of asphalt after compaction. Aggregate should not exceed 3/8″ in size.

The proper type asphalt used for the overlayment will vary from state to state if using the standard norm of the Department of Transportation (DOT) or State Highway Department standards.

Thickness: Not less than 1 1/2″ prior to compaction.

Liquid Asphalt or Bitumen: 5.5% by weight (+/- 0.5%)

Asphalt Penetration or Type: (85 – 100 penetration)

Aggregate Type: Crushed stone, gravel, shale, limestone, etc. Slag is unacceptable. Foreign materials, i.e., pyrite clay, ferrous compounds, dirt and organic compounds, should not exceed 3% of the total volume of aggregate.

Installation Equipment: Self-propelled paving machine with vibratory screed.

Rolling: Not less than 3 to 5 ton tandem steel wheel roller with working watering system.

Finish Rolling: Not less than 1 ton tandem steel wheel finish roller.

Flood Check: Any ponding or “birdbaths” remaining after one hour in minimum 70 degree Fahrenheit in sunlight and which cover a five cent piece (American coin) should be filled prior to any further applications.

Voids Content: Minimum as specified by the Department of Transportation or State Highway Department, but in no case should void content exceed 7%.

D. Surface Repair
1. Birdbaths
Any areas holding enough water to cover a five-cent piece after one (1) hour in minimum 70 degree Fahrenheit in sunlight, should be outlined with chalk, and the water swept out. After the area is surface-dry, a tack coat of suitable material must be applied to the entire area within the chalk-line.

Estimate the required quantity of the thin patching mixture required to fill such “birdbaths”. Apply it to the area, and strike off with a straight-edge the length of which is in excess of the dimensions of the “birdbath” to the same elevation as the surrounding surface. After the leveling operation, the patch should be allowed to cure properly.

There are various materials to accomplish the above patching methods. They should be used in accordance with the material manufacturer’s specifications.

2. Fiberglass Membrane System
This method is designed to restore the surface of certain types of cracked courts, and provide a smooth, dense, water-tight playing surface. There are several products on the market that should be installed as per manufacturer’s specifications. These treatments are not intended to restore a badly cracked or broken surface, nor to permanently seal cracks subject to base movement.
3. Color Finish Course Re-Coating
Re-coating of the color finish course should proceed after all repairs have been completed and all appurtenances such as net post sleeves and anchors, fences and gates have been checked and maintenance performed where needed. On tennis courts not requiring repairs, only re-coating, the following procedures will be the guide. Over the suitably prepared surface of the tennis court, apply one or more coats of material in accordance with the coating manufacturer’s recommendations. Acrylic resurfacing materials are suitable as a base coat, but the final applications should be acrylic color coatings made for tennis courts.
5.0 Regular Housekeeping Maintenance
A. Outdoor Acrylic Surfaces
Outdoor acrylic surfaces are relatively easy to maintain due to natural cleansing by rains. Problems may develop due to lack of proper drainage or soil erosion. Surfaces may become coated with mud and dirt, pine needles and leaves, and other foreign matter which should be removed as required.

Suggested maintenance for outdoor acrylic surfaces is to keep the court clean at all times by occasional sweeping in order that dirt and foreign particles do not get ground into the surface by foot traffic. During the tennis season the courts should be hosed off with water periodically (once a month) and allowed to dry. Do not use a stiff bristle broom but soft nylon or hair types for sweeping. Use normal water pressure for hosing (approx. 70 lbs. per square inch or less). Should there be any stains on the court, they may be removed by application of a mild cold-water detergent and scrubbing with a hair-type scrub brush. Should mold or mildew form on the courts in shady areas, an application of diluted strength household bleach (minimum 2 parts water, 1 part bleach) may be used to remove the fungus and retard its further growth. Where areas are treated, they should be rinsed off after a few minutes to remove the surface contamination. (NOTE: Fungus grows on surfaces contaminated by foodstuffs, soft drinks, and decaying matter. Acrylic coatings do not support fungus growth.)

B. Indoor Acrylic Surfaces
Indoor acrylic surfaces become significantly more dirty than do outdoor surfaces and, because of dust, tracking in of dirt, ball fuzz, and other extraneous materials, the courts can become rather unsightly in a short period of time.

Indoor clubs generally have a regular schedule of cleaning maintenance in which the courts are swept by vacuum or by rotary sweeper once a day and cleaned either by water vacuum or self-contained water brush units approximately once a month. If they are not water cleaned approximately once each month, dirty indoor courts may show the formation of mold or other fungus growths due to a combination of humidity and temperature, along with contamination from perspiration, foodstuffs, soft drink spills and dirt tracking. Again, this fungus may be removed by the use of a bleach solution such as mentioned above.

In using the water brush unit, detergent should not be mixed with the water, and the water should be clear, cool, and free from contaminants. During the cleaning process, the water should be changed frequently. Again, as in the case of outdoor courts, if the indoor courts are stained by foreign matter, such as soft drinks, food, grease or other materials, then a mild cold-water detergent should be applied to the stained area and lightly scrubbed with a soft bristle brush.

The majority of color surfacings are acrylic synthetic polymers. For synthetic surfaces other than acrylics, contact the manufacturer for specific maintenance instructions

Note: Refer to Guidelines for:
1.A. General Conditions for Construction
2.A. Tennis Court Orientation
2.B. Tennis Court Dimensions and Related Measurements
2.I. Hot Mix Asphalt Tennis Courts
2.O. Acrylic Color Finish Systems for Tennis Courts
2.P. Resurfacing Asphalt Tennis Courts

ASTM specifications are available from
American Society of Testing Materials (ASTM)
100 Barr Harbor Drive
West Conshohocken, PA 19428

NOTICE: These Construction Guidelines are for use by architects, engineers, contractors, tennis court and running track owners. Parties not experienced in tennis court or running track construction are advised to consult a qualified contractor, consultant and/or design professional. Experienced contractors, consultants and/or design professionals can be identified through the U. S. Tennis Court and Track Builders Association. Due to changing construction technology and techniques, only the most recent version of these Guidelines should be used. Variances in climate, soil conditions, topography and other factors may make these Guidelines unsuitable for certain projects.

Copyright © 1998 by U.S. Tennis Court and Track Builders Association. All Rights Reserved.