There has been a lot of talk lately on using laser equipment to add a “lift” to existing/old HarTru tennis courts. I will get into the pros and cons of this but first I want to provide a little background information and terminology to make sure that everyone is on the same page.
HarTru – HarTru is a brand name and in today’s market it is the primary source material for crushed stone clay like tennis surfaces. Over the history of these type of courts there have been many names and brands: Rubico, FastDry, HarTru, TruTop, clay, etc. The primary deciding factor in these courts is that they need daily maintenance, water and rolling. They are not a permanent surface such as asphalt or concrete. HarTru courts allow water to pass through the surface as opposed to simply flowing off of the surface. HarTru courts are much easier on a players legs, back, knees and ankles.
Lift – A lift of a HarTru court is typically the adding of 3/4″ to 1″ of new HarTru surface material. A standard single HarTru court with a dimension of 60’x 120′ would require 40 tons of HarTru when built new. So a lift would add approximately 30-40 tons of new material to the existing surface. Lifts are usually only done when either the base stone or screenings are showing through the surface indicating that the original one inch layer of HarTru has either worn down or eroded to the stone leaving a 1/8″ or less depth of the originally constructed HarTru surface.
Base – When I refer to the base of a HarTru tennis court I am referring to either the 3/4″ washed stone base or a crushed screening base or both. In the 60’s and 70’s we always used a primary base of 2.5″ of 3/4″ washed stone followed by a 1.5″ layer of crushed granite or stone screenings. This combination provided a 4″ stone base under the one inch of new HarTru surface material. The different stone bases offer two different purposes.
3/4″ Washed stone – The 3/4″ washed stone which was the first base layer installed over the existing cleared and graded ground is primarily a structural layer. The 3/4″ stone provides stability and compaction to the playing surface. An additional role is that the washed stone serves as a drainage base for the surface helping to absorb an overflow of water in heavy rains.
Screenings – The screenings layer, which is normally 1.5″ thick, acts as the moisture reservoir for the surface HarTru material. By holding water and then releasing that moisture, when needed, the screenings acts as a storage for the HarTru surface allowing the stored moisture to be pulled up into the HarTru surface as the surface starts to dry out. This is a critical layer, especially in the summer, to keep the HarTru surface as moist and playable as possible.
Some HarTru History – Clay or soft surface tennis courts have been around since the beginning of tennis. Grass courts as well. Asphalt and concrete courts were a later introduction to the tennis court surfacing industry. HarTru courts in the early years, up until the 80’s and early 90’s were mostly built by intensive hand labor. Only the most disciplined and proud builders were able to build HarTru courts to the exacting tolerances these courts required. When you are dealing with layers from 2.5″ to 1″ thick over areas that may measure thousands of square yards the diligence and effort required to maintain these requirements was very very difficult. In the 80’s and early 90’s with the invention of the laser guided grading equipment this situation changed somewhat. Although still not an exact science the laser technology added a great deal of advantages over hand work. But laser technology has it’s issues as well and require operators that are experienced and very methodical and disciplined to operate the equipment properly.
Bottom Line – The bottom line to building a great HarTru tennis court is to make sure that all of the layers of construction – from the ground prep, stone prep, screening prep and HarTru surface installation – are all carried out to near perfection. If there is any deviation off of grade or pitch or any deviance off of depth or integrity of materials the subsequent tennis court will have problems. These problems may be poor drainage, poor water retention, inconsistent drying patches and inconsistent compaction. All and any of which will make maintaining the HarTru court a difficult and expensive proposition. The statement – any house is only as good as the foundation it is built upon, applies to tennis courts as well. There is no “after completion” correction if the installation of the court is done wrong. Build it right the first time – that is the only mantra that works.
LIFTS and LASER GRADING:
All of the above information has brought us to this point. All tennis courts are not created equal. All tennis courts do not have perfect grades, perfect pitches, perfect depths of base material and perfect elevation changes. And if they don’t – you should not laser grade your courts to provide a lift.
As seen in the below cut this is how a properly built HarTru court should look if you were able to have a side view. All layers consistent depth, all layers consistent materials and all layers consistent compaction. A well built tennis court:
As seen in this fictitious cut of an improperly built court below, this is how some courts are built. Inconsistent layer depth, inconsistent compaction and inconsistent material quality. A poorly built court makes it all but impossible to simply laser grade.
In this representation we are showing you that a laser guided piece of equipment although very accurate and consistent does not have the ability to think. A laser is somewhat like a bulldozer in that it doesn’t care what it cuts or fills. It only cares that it cuts or fills to stay in line with the laser beam. In other words it can’t tell if it is completely cutting through the surface layer, screening layer, stone layer or two of the layers or even all of the layers. The laser only knows that it has to stay on line. So, whatever gets in the way it will cut and wherever it is low, it will fill. It will fill even though there may already be an inch or more of HarTru material there. The laser doesn’t care what is there or isn’t there. The laser only cares about keeping itself at the exact elevation line.
So here lies the problem. If an existing tennis court doesn’t have perfect grades, perfect depths, perfect elevations the act of using a laser to re-grade the existing tennis court may, in fact, cause a much worse situation than it fixes. If the laser re-grade cuts through the screenings, the court in that area, will drain way too fast and not hold/retain any moisture. If the laser fills, by adding more HarTru or more screenings, that area of the court will drain very slow and become, over time, very soft. You can not destroy the integrity of a court and expect the court to work properly.
The only solution to the laser re-grade issue is to take careful boring of the existing courts to check out the depth and quality of the base materials in multiple (6 or more per court) locations. By doing these geotechnical borings you can ascertain whether or not the court(s) are built in such a way that the laser re-grade will work. If they are – then great. If the existing court(s) were not built properly or if over time they have settled, sunk or shifted the laser re-grade won’t work. In this case you have to do a surface re-build. You will have to add a new curb, new base materials and a new inch of HarTru. You will still have your fencing and irrigation system so there will be monies spared there. Your net posts can be raised or re-installed but the surface itself will have to be re-built.
The great news is that once the re-build is done your courts will play much better and the maintenance labor and dollars necessary to keep them up will be much less. You will finally have what you should have had the whole time – a great playing surface that is relatively easy and inexpensive to maintain!!