Tennis Industry magazine


Clay Courts Indoors?

Efforts are under way to increase knowledge and improve playing conditions on a surface typically reserved for outdoor play.

By Pat Hanssen

Indoor facilities play an essential and often overlooked role in the tennis industry. In the northern half of the U.S., for as many as nine months of the year, they are the lifeblood of the game, providing access to leagues, lessons, tournaments, and the accompanying healthy, fun, social interaction.

Although they are found in abundance in the northern half of our country, some may be surprised to learn there are indoor facilities as far south as Alabama. They are even being talked about in Florida, where there are pressures to flee the intense summer sun for cooler, skin-safe environs.

As the baby-boomers, and the largest percentage of the avid tennis playing population, sprint toward the years once known as “retirement,” providing access to tennis court surfaces indoors that are easy on the body, and will allow this group to play tennis well into old age, is increasingly relevant for facility owners, managers, and teaching professionals, all eager to attract and retain this well-to-do customer segment. Clay, and the American version of it known as Har-Tru or fast-dry, is one of these surfaces.

It has long been known that a soft surface like clay is easier on players’ joints. But clay is not typically at the top of the list for indoor installation, for two basic reasons: 1) Indoor clay courts play differently than outdoor clay courts, tending to be harder and more slippery, and 2) indoor clay courts are more difficult to maintain than outdoor clay. When you add in concerns about wear and tear to the structure housing the courts from exposure to humidity over long periods, it’s not hard to see why clay has been low on the priority list as far as a surface for indoor facilities.

But recent developments are helping make clay courts in indoor facilities a more viable, and indeed desirable, option.

At my company, Lee Tennis of Charlottesville, Va., which manufactures Har-Tru, developing tools and techniques for maintaining clay courts is a part of our culture. We have long realized that the simpler the maintenance and the better the courts, the easier it becomes to sell. Years of research and innovation have helped to reduce maintenance needs on outdoor clay courts from three hours per day to as little as 20 minutes per day.

But up until three years ago, very little work had been done to improve playability and decrease maintenance on indoor clay courts. The reason for this is in the numbers. There are an estimated 30,000 outdoor clay courts, vs. less than 500 indoors. But with the recent interest in bringing the sliding benefits of clay indoors, we’ve been taking a close look at what needs to be done.

indoor clay courts

Customer Satisfaction

At Lee Tennis, the first thing we did was to compile an inventory of existing indoor courts and to get a feel for court conditions and customer satisfaction. A visit to 19 facilities in the Northeast in January 2004 revealed that for the majority of them, both the people maintaining the courts and those playing on them were very unhappy. From facility to facility, there was no consistency in either the maintenance routines or the problems, and generally there was confusion about what should be done to keep the courts in the best shape.

Facilities had been left to their own devices to come up with the best routines they could to keep the courts safe and playable. A few were doing quite well and achieving considerable success pleasing their playing public, but even at those locations, there was concern over a perceived lack of control over court conditions and over the lack of any support from the manufacturer or any industry trade associations.

In response, we hosted a conference on indoor clay courts on Long Island, N.Y., that August to bring together builders, owners, managers, teaching professionals, and maintenance personnel to gather knowledge and share ideas and concerns. Close to 40 people attended what became the first of our Annual Conference on Indoor Clay Courts.

According to conference attendees, players expect that clay courts indoors should play the same as clay courts outdoors, yet they rarely do. The controlled, comfortable slide on outdoor courts is replaced by a slippery court that often is too dry.

There were three areas of concern: surface compaction, irrigation, and humidity. Severe compaction occurs indoors because of the extremely high use, and this compaction creates a surface that is bald, slippery, and difficult to irrigate. Water can and will help soften the courts, but with low evaporation rates indoors, it is difficult to irrigate the courts in a way that maintains an appropriate amount of water in the surface profile.

Flooding the courts with too much water is a real concern because they take so long to dry, and that increases the humidity levels in the building. Whether the indoor courts are in a permanent structure or an air structure, controlling humidity levels is vital to make the playing environment safe and pleasant. Simultaneously trying to keep the court surface wet and the air dry is a bit of a conundrum. In relative humidity greater than 65 percent, condensation occurs more frequently and mold and mildew start to grow. Too much humidity also allow the tennis balls to get dirty and heavy.

The interconnected nature of these problems made resolving, or at least managing, these issue quite challenging, but some of the work that we had done on outdoor courts applied to indoor clay courts, too. For instance, several aggressive tools had been developed for use on outdoor, sub-surface irrigated courts, which also tend to get very hard and are susceptible to algae and moss. It was found that these tools could be incorporated into the daily, monthly, and annual routines effectively to break up the hard surface layer and make it safer and less slippery.

Another outdoor strategy tested and successfully brought indoors was aerating courts. By using machines that shoot highly pressurized jets of water into the court surface, cavities were created to allow courts to expand and soften and water to penetrate more freely.

New Manual

The outcome of this work was a new Indoor Maintenance Manual for clay courts. The manual was introduced last August at the Second Annual Conference on Indoor Clay Courts. While we consider this manual a work in progress, it has created a baseline to work from by outlining the challenges, explaining why they occur, and offering strategies for managing them. It is available to the general public at Lee Tennis’ website, (Also from the website, users can link to an “Indoor Forum,” where current and potential indoor clay court personnel can share ideas, post pictures, ask questions, and more.)

In conjunction with the new manual, we’ve also launched research aimed at quantifying optimal surface compaction, moisture content, and traction. For this research, we’re utilizing the assistance of some of the best soils scientists in the country and hope that by understanding the science of what is making courts so hard, they can provide better solutions for court maintenance. There is ongoing testing at two facilities in Virginia, and we will be conducting tests at more than 15 facilities along the East Coast.

When it comes to maintaining indoor clay courts, we still have a lot to learn, and challenges still to overcome. But, for the first time, we know what those challenges are and have taken steps to find workable, practical solutions. For instance, we’ve standardized maintenance routines and tools and equipment to achieve excellent results in terms of playability, and we’ve developed ways to communicate this information to current and potential court owners.

We’ve also begun to quantify scientifically what owners and players consider “good” and “bad” in terms of playing conditions. As the data comes in, we’ll use it to develop new tools, techniques — and maybe even new surfaces — that will change the way people feel about clay courts indoors.

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About the Author

Pat Hanssen  is the director of sales and marketing for Lee Tennis Court Products in Charlottesville, Va. An active player and coach, he is the past president of USTA Virginia and vice president of USPTA Mid-Atlantic Division.



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