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Clay tennis courts originally appeared in the early 1900s in Europe as an alternative to grass. Clay tennis courts are favored by many players because they have a soft surface that is very forgiving on the knees, and the texture of the court slows down the ball significantly compared to a hardcourt or grass tennis court. In this article, we will examine how a clay tennis court is constructed from the ground up. Then we will check out how the most popular claycourt surface in America, Har-Tru, is created.
Tennis Claycourts: The Construction of a Clay Tennis Court
A clay tennis court is, compared to an asphalt hardcourt, relatively simple to build. Construction begins by removing soil from the tennis court location. In the case of American clay courts, about three inches is usually dug out. In Europe however, some red clay tennis courts may be dug out as much as two feet.
Tamping machines are then brought in and the soil is compacted until it is extremely dense. Great care is taken to create the grade (the slope) of the tennis court, which runs diagonally from corner to corner. As an alternative, sometimes the entire court is simply sloped sideways in one direction (the slope is barely noticeable though). Unlike tennis hardcourts however, the slope is never divided along the court centerline or the netline.
Once the sub-base is leveled, the court area is surrounded by a border of brick or wood that acts to contain the stone and clay that will be added. At this point, the base layer of rock is laid down. Depending on the specifics of the site, the rock added in this phase is usually about three quarters of an inch in size, leaving space between the rocks. The thickness of this layer also varies greatly depending on the type of construction. The red clay courts at Roland Garros (the French Open) have almost two feet of crushed limestone rock underneath as a base. American courts usually only have about four inches of base. Because of the low amount of sand in this base layer, it acts to stabilize the court surface above.
It is in this base layer that subsurface hydration systems such as HydroCourt are put in place. Underground irrigation of this type has become the latest craze in clay court construction because it greatly simplifies maintenance and makes the courts playable all year round in temperate climates. Plastic tubing is laid down as the rocks are added and compacted, and the tubes are then connected to a water reservoir. Clay courts evaporate significant amounts of water into the air at the surface, and this causes moisture to be wicked up through the various base layers from the irrigation tubes. This minimizes the amount of watering that must be done with a garden hose to the surface of the court. About three quarters of all new clay courts being built today have some sort of subsurface irrigation system.
Once the base layer and irrigation system are laid down, about two to three inches of a crushed rock and clay mixture are added on top and compacted using a heavy roller. This layer serves to help smooth out any inconsistencies in the base layer. Finally, the “top dressing” is added to the court, which is usually about an inch thick of highly compacted clay. This is the playing surface. Vinyl tape is then laid down to mark the lines of the court. Long nails are driven down through precut holes in the tape into the highly compacted clay below, and the court is ready to play!
Most new tennis claycourts are constructed in this relatively simple manner as outlined above: dig out, lay down rock, lay down smaller rock, and finish with pure clay on top. It is relatively inexpensive to construct a claycourt, but these courts tend to require much more maintenance (even daily maintenance) than a hardcourt. Because of this, the costs of claycourts are spread out over the life of the court much more so than a hardcourt, where much of the cost is up front in the construction.
So now that we know how claycourts are built, let’s take a look at the most popular American brand of clay surfacing, Har-Tru.
Tennis Claycourts: Har- Tru
Har-Tru is the claycourt surface you’ll find at most tennis clubs around the United States. Har-Tru’s origins, however, lie in England. In the early 1900s, clay courts were manufactured in Europe using a product called En Tout Cas, which was made of crushed and powdered red brick. A man named Henry Alexander Robinson was a local tennis court contractor using En Tout Cas, but he was searching for a better alternative. He learned that the Funkhouser Company (a roofing tile supplier) in Pennsylvania had a large supply of crushed green stone that was a waste byproduct of its roofing business, and was intrigued. He voyaged to America and convinced Funkhouser to allow him to experiment with the green stone as a tennis court surface.
The first green clay court was constructed in 1931, and Robinson’s wife decided on a name for the product. She combined her husbands initials, HAR, and the “true” clay color (no coloring was added to the clay), and Har-Tru was born. Har-Tru remained a subsidiary of Funkhouser Co.
In the 1950s, Funkhouser put Robert Lee, a recent college graduate, in charge of the Har-Tru division. He eventually left the company in the late 1960s and started his own to compete with his former employer, but not before finding a new source of stone: The billion-year-old metabasalt deposits surrounding Charlottesville, VA. The quarries were owned by the Luck Mining Company. The rock itself is relatively brittle, and it is baked and put through a series of enormous breakers that turn the rock into a fine, consistent powder.
Business boomed for both companies during the 1970s and 1980s, but eventually the market began to shrink, and in the 1990s the Pennsylvania Har-Tru brand was forced to close. Lee had his eye on the brand name, however, and eventually purchased the rights to it. The Har-Tru brand and business was then purchased by its stone supplier, Luck Mining. Today, Har-Tru is the premiere clay court surface in America.
Har-Tru courts begin by tamping down three inches of a mixture of ¾” stone and fine dust using a 600-pound roller. This crushed stone aggregate serves as the base for the court, and it is in this layer that underground hydration systems such as HydroCourt are laid. Construction of this sub-base layer actually varies quite a bit from location to location, usually based on available local stone. Gravel, limestone, slag, washed shell, and even cinders are all acceptable.
Next, a layer of smaller ½” stone and dust is layed down about an inch thick. This layer serves to level out the surface in preparation for the Har-Tru surface dressing. This layer is then also rolled and compacted with a roller.
The Har-Tru topcoat is then laid down one and a quarter inches thick, and is then rolled down to one inch thick. Har-Tru surfacing comes in huge batches delivered by truck to the tennis court site. It takes about 40 tons of Har-Tru to cover a tennis court to a depth of one inch. When you need more Har-Tru material to maintain your tennis court, it arrives on a pallet in eighty-pound bags.
A diagram showing the layers of a Har-Tru tennis court.
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