Building a new court: what happens before the first load of stone

People think a court is built the week the color goes on. The court is built in the month before that, in dirt and stone, and nothing we do with a squeegee can fix what was done wrong with a compactor. Here is what happens before the first load of asphalt, and why each step is there.

What is under the court

Most of Northeast Ohio sits on clay, and clay is the enemy of a flat slab: it swells when wet, shrinks when dry, and heaves when it freezes with water in it. Footings go below the frost line, which each local code sets and which is around a yard in most of our towns. A court built on clay that is wet in November is a court that lifts in February. So the first question on a new site is what the ground is and where the water in it goes, and the answer decides the base thickness, the drainage and sometimes whether the court goes there at all. On a big job we take soil borings; on a small one we dig test holes with a backhoe and look.

Layout and orientation

The pad is set out by instrument: 120 by 60 feet for one tennis court, bigger for tournament run-off, with the fence line, net post footings and light bases located before anything is dug. North to south along the length wherever the site allows, so nobody serves into a low sun. The long axis also decides where the water goes: a court slopes one percent in one plane, and the low side needs somewhere to send the water that is not the neighbor's lawn.

Excavation and subgrade

The topsoil comes off and the pad is cut to the finished plane less the thickness of the base and the asphalt. The subgrade is compacted with a vibratory roller until it stops moving, and it is proof-rolled: a loaded truck is driven over it and anywhere it pumps or ruts is dug out and replaced with stone. A soft spot found now is a small fix; found under a finished court, it is a heave that comes back every winter.

Drainage

Water that reaches a court has to leave on the surface, and water in the ground has to be kept out of the base. A swale or a drain along the high side intercepts the lawn's runoff; a perimeter drain in stone around the pad lowers the water table under it; the pad itself is graded so that water leaves at the low side into something that can take it. Drainage is the least visible money in a court and the money that decides how long it lasts.

The stone base

Six to eight inches of crushed limestone, angular so it locks, placed in lifts of no more than four inches and each lift compacted and checked to the plane with a laser. The base is the court: the asphalt follows its shape and the coating follows the asphalt. A base that is a quarter inch high in one spot is a birdbath forever. We check it with the laser and with a ten-foot straightedge, and we check it again after the first rain.

Asphalt

Two lifts: a binder course of coarser mix for strength, rolled, then a surface course of fine-graded mix for a tight surface the coating can seal. Both rolled while hot to the plane, with the roller kept moving so it does not sit and leave a dip. The ASBA's guideline for tennis courts specifies the mix, the lifts and the planarity, and it is in the resources section for anyone writing a bid.

Cure

New asphalt is full of light oils that have to leave before an acrylic coating will bond, and that takes 20 to 25 days of warm weather; our own proposals say so in writing. We test it: a patch of coating in a corner, and if it bonds and stays bonded after a week, the court is ready. Coating green asphalt is the most expensive shortcut in the trade; the color peels in sheets the next spring and the whole surface has to be stripped.

Then the court

Flood test, patch any spot that holds water, and the surface goes on: resurfacer, color, lines, nets. The construction page lists those steps. A new court on a base built this way lasts thirty years with resurfacing every six or so; a court on a base built in a hurry lasts until the second winter. The month in the dirt is where the thirty years come from.