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2. construction

How to design and build
reinforced concrete
tennis courts
These special-purpose slabs require careful attention to site preparation,
drainage, reinforcement and finish
PREPARED BY CONCRETE TECHNOLOGY
SECTION, PORTLAND CEMENT ASSOCIATION, SKOKIE, ILLINOIS
T
he development of championship tennis players has, in the
opinion of experts, been due as
much as anything to the fast, unif o rm - t e x t u re surface of a concrete
tennis court. The true, even surface
assures a consistently accurate
bounce of the ball, a feature essential to superior play.
Properly constructed, a reinforced portland cement concrete
slab will endure many years of exposure to the weather with little or no
maintenance and continue to provide the paving surface necessary
for good play on either public or private courts.
Site selection
In northern latitudes tennis
courts are traditionally oriented
with the long axis placed in a northsouth direction and the net running
in an eastwest direction. The United States Tennis Association (USTA)
suggests that, south of the 42nd parallel of latitude, the long axis of the
court be oriented 22 degrees counterclockwise of north to reduce the
amount of direct sunlight in the
p l a ye r s’ eyes during prime playing
time.
Ground at the site should be reasonably level and uniformly
drained. The direction of surface
drainage of the courts should be
considered. Also, an examination of
the site by a professional soil engi-
neer may be warranted to establish
its suitability for tennis courts.
Other considerations include
shelter from prevailing winds and
space for future expansion. For
championship play, courts should
be set away from trees that may cast
s h a d ow s, shed leaves or ove rh a n g
the playing area, though on courts
for ordinary recreation shade trees
provide welcome relief from the
sun.
Subgrade and subbase
Graded to the profile desired for
the court, the subgrade should be
uniform, hard and free from organic
matter. If it is necessary to cut down
trees in clearing the site, the roots
should be removed so that subsequent decay will not cause settlement of the court. The site should
also be cleared of all sod, humus
and other rich organic matter.
There usually is little opportunity
to improve the subgrade except by
compaction and drainage. It is important that the support be made
reasonably uniform with no abrupt
changes from hard to soft. Special
care must be taken to ensure that
there is control of the major causes
of nonuniform support: expansive
soils, hard and soft spots, and backfilling.
It is seldom necessary or economical to provide a thick subbase, the
layer of material placed between the
subgrade and the tennis court pavement. The slab strength is achieved
most economically by building
strength into the concrete itself.
Since the subbase of a tennis court
serves as a leveling course for fine
grading and as a cushion for obtaining uniform support by equalizing
minor surface irre g u l a ri t i e s, it is
possible to construct a satisfactory
tennis court without any subbase.
Where subbases are needed, a thin
layer—4 inches or less—is suggested.
Drainage
Artificial drainage is provided to
avoid pools of standing water, to reduce uneven frost heave and to afford fast surface drainage of the
courts so that play can resume as
quickly as possible after a downpour.
If the site does not have good
drainage, concrete drain tile should
be provided in a trench at the
perimeter of the court. The trench
is placed at or near the edge of the
slab to a depth of several feet and
the bottom sloped about 1 inch in
every 10 feet to natural drainage or a
storm sewer. Concrete drain tile is
laid with open joints that are covered with roofing felt or other suitable materials to prevent soil or dirt
from entering after backfilling.
Coarse gravel or crushed stone,
ranging in size from 1 to 1 1/2 inches, should be placed over the drain
tile to a depth of at least 12 inches.
Above that point a filter-grade sand
can be used up to the re q u i re d
g ra d e. If the courts are on the side
of a hill it may be sufficient to provide drainage or a cutoff wall on the
uphill side only. (Sloping the court
surfaces for rainwater runoff is discussed under “Layout.”)
Layout
The layout of a single court is given in Figure 1. It shows the regulation playing area of 60 by 120 feet inside the fencing. Where space or
funds are limited, as for a pri va t e
court at a residence, a playing surface 52 by 110 feet may be satisfactory.
For a bank of courts a space of 10
to 12 feet is allowed between courts.
A trio of courts is illustrated in Figure 2. In this case no fence is provided between courts. If a fence is desired between courts, 10 or 12 feet
should be allowed between the
fence and the side playing lines.
Outdoor courts made of nonporous materials such as concrete
should be built to a pitch of 1 inch in
e ve ry 10 feet with the entire playing
area in the same plane. The two
halves of the court should not both
be pitched to or from the net because this would, in effect, change
the height of the net. Preferably the
entire court should be pitched from
side to side. The USTA discourages
construction of courts pitched end
to end because the lower court will
remain wet longer after a rain. In the
case of a pair of adjacent courts the
pitch of each court can be toward
the outer edge; this avoids a valley
or drain between the courts.
Warping of the court slabs to
achieve a pitch in a valley is not permitted by the USTA. On the other
hand, the courts can be pitched at
an angle (Figure 2) and this will produce a pitch in the valley.
Sloping a court is merely a matter
of convenience to drain any rainwater. It has nothing to do with tournament rules as long as the entire
court is in a continuous plane; indoor courts are built dead level.
Thus, in the case of a bank of three
courts there are other ways to slope
the courts than those shown in Figure 2. For example, the center court
could be dead level and the two outer courts could be sloped down to
the outer edges. Also, the courts
could be sloped directly to the sides
but drain inlets would be needed in
the dead-level valley to hasten
drainage there.
Types of concrete courts
Concrete tennis courts are constructed in various ways depending
on the available funds and the contractor’s construction preferences or
capabilities. The type recommended for most installations is the continuously reinforced court. Having
reinforcing bars throughout, it is
jointfree in the playing area. If the
concrete is continuously cast over
the entire court, no joints are required; if concrete is continuously
cast over only one-half of the court,
an expansion joint should be provided in the slab under the net. If
two or more courts are constructed,
expansion joints should be provided
midway between courts. Slab reinforcement and joint details for this
type of court are shown in Figure 3;
a cross section and other typical
tennis court details are shown in
Figure 4.
These large slabs are strength-
Figure 1. Layout of a single reinforced concrete tennis court. The larger dimensions shown for the
distance to backstops and sidestops are USTA regulation court dimensions for tournament play.
ened in each direction with reinforcing steel bars having an area equal to
0.5 percent of the concrete crosssection area. This amount of reinforcement will hold shrinkage cracks
tightly closed and eliminate any differential vertical movements at the
cracks. Concrete tennis courts containing this percentage of reinforcement will retain a smooth, playable
surface for many years.
The second type is the jointed
court shown in Figure 5. The area
within the playing lines (shaded)
constitutes about half of the total
court area. It is reinforced with bars
and has no joints while the remainder of the court (where the bounce
of the ball is not critical) has mesh
reinforcement and control joints.
Thus a savings in materials is effected. Some contractors find this to be
an easier and less costly way to build
a court.
When an integrally colored concrete topping is to be applied the
control joints are placed at the outside edge of the playing lines. Otherwise, joints are preferably placed
about a foot outside of the playing
lines (because during play a ball is
fair if it hits a line).
Instead of using sawed or tooled
joints at Section B-B in Figure 5,
these control joints can be formed as
shown in Section A-A and reinforced
with steel mesh alone. If desired,
joints at A-A can be sawed or tooled
but a formed joint with a bond
breaker is preferred.
A third type of concrete court is
the prestressed court. It is buiIt with
prestressing steel strands pulled taut
to put about 100-psi compressive
stress in the concrete; this counters
the tendency toward shrinkage
cracking and provides a cra c k - f re e
concrete playing surface. A slab 122
by 205 feet for a bank of four courts
can be constructed in this manner
without any joints. Another advantage of this large, unjointed slab is
that it can be sprayed and used as a
natural ice surface for winter skating; an artificial ice surface can be
made by installing refrigeration coils
in the concrete. A further advantage
Figure 2. Layout and spacing for a bank of three outdoor courts.
The slopes shown avoid the need for drain inlets between courts
(and drain tile beneath the slabs) while maintaining each entire
court in a continuously pitched plane.
Figure 3. Slab reinforcement and expansion joint details for
the continuously reinforced type of court. There are no joints
except under the net and between courts.
Figure 4. Cross section at the net of a continuously reinforced type of court.
Other typical tennis court details are also shown.
Figure 5. Layout for jointed type court with control joints in the slab
outside of the playing lines—offering some court dimensions shown
in Figure 1.
of this type of court is that the large
paved area without joints or cracks
is well suited for roller skating.
In the three types of concrete
courts just described, it is assumed
that there will be no other construction joints; they would have a tendency to develop a slight ra ve l i n g
that would interfere with the uniform surface texture needed for a
tennis court. If emergency construction operations do require a
construction joint, it should be
formed with a bulkhead (as shown
in Section A-A of Figure 5) but bond
should be developed at the interface.
Guide for Ordering Concrete for Outdoor Tennis Courts*
Maximum-size aggregate
Inches
Millimetres
Pounds
per cubic yard
Kilograms per
cubic metre
Air
content
percent by
volume
3
9.5
12.7
19.0
25.4
38.1
610
590
540
520
470
362
350
321†
309†
279†
71⁄2 ± 1
71⁄2 ± 1
6±1
6±1
5±1
⁄8
⁄2
3
⁄4
1
11⁄2
1
Minimum cement content
* The concrete should have a slump no higher than 4 inches and a com-pressive
strength at 28 days of 3500 psi.
† In areas exposed to a number of freeze-thaw cycles it is advisable to use a minimum cement content of 560 pounds per cubic yard.
Slab thickness
A 5-inch-thick tennis court slab is
recommended for outdoor courts in
severe climates such as in Wyoming,
Iowa, and Ohio. A 4-inch-thick slab
is recommended in mild climates
such as in Florida and the coastal
areas of California and Texas. The
choice of concrete thickness in other areas is a matter of judgment.
Many factors influence the slab
thickness required. They include the
range of temperature change, moisture variations in the slab, drying
and carbonation shrinkage of the
c o n c re t e, expansive soils, any
nonuniformity of the subgrade support and quality of construction.
Concreting procedure
It is important that the correct
quality of concrete be specified and
used. The concrete must have durability to withstand weather extremes and the ingredients must be
selected so that the concrete can be
readily placed and finished.
The maximum size of aggregate
should not exceed one-third of the
slab thickness. The minimum cement content and the air content required for each of several maximum
sizes of aggregate are given in the
table. In some instances a cement
content higher than that given may
be necessary to obtain 3500-psi
concrete.
Reinforcing bars are used to hold
any concrete cracks tightly closed so
that they do not interfere with the
bounce of the ball or the footwork of
the players. They should be tied together with soft iron wire and supported at middepth in the slab on
slab bolsters or concrete bricks as
shown in Figure 3. The bars should
be lapped at least 18 inches (in order
to transfer the stress from one bar to
the other) and the laps staggered. In
the case of mesh (welded wire fabric), support accessories must be
more closely spaced because the
wire will easily bend out of shape
under the weight of a man.
Of all the slab placing and finishing operations, screeding has the
greatest effect on surface tolerances.
Wet screeds or pipe screeds may be
used.
The practical way to consolidate
the concrete in a 4-.or 5-inch thick
tennis court slab is with a vibrating
strikeoff. This gives positive control
of the screeding operation and saves
a great deal of labor. This method is
recommended when the slump is
less than 3 inches.
Finishing
Finishing operations follow the
practices normally recommended
for flatwork* with some special
modifications needed for tennis
c o u rt s. Immediately following
screeding the concrete is further
leveled with a darby or bullfloat.
Following this there is a slight wait
for stiffening of the concrete until all
bleed water is gone from the surface
and it will sustain foot pressure with
only about a 1⁄4-inch indentation.
Edging is required at control
joints if the jointed court shown in
Figure 5 is chosen. The edging tool
should have a 1⁄5-inch radius. The
slab is then floated.
The final finish of the concrete is
very important to the play of the
tennis ball. Too rough a finish will
slow the ball and footwork and
cause excessive wear on balls and
shoes; too slick a finish gives too little spin and bounce and makes
footing less sure. Uniformity of the
surface texture is also important. A
proper finish can be achieved with a
swirl pattern produced with the flat
of a trowel moved in small circular
movements. A light broom finish is
equally suitable. To be certain that
the finish will satisfy an athletic director or tennis pro, the surface can
be made slightly rougher than necessary and reduced to the desired
texture by a light grinding after curing.
If a color coating 1⁄16 inch or more
thick is to be applied it will furnish
its own texture and all that is required on the concrete is a light
broom or steel-trowel finish.
Curing
Moist curing is done either by wet
covering, sprinkling or ponding to
offset loss of moisture or by sealing
the concrete surface with plastic
sheeting or waterproof paper. Use of
a curing compound is not recommended on a tennis court because it
may inhibit bond between the concrete and the paint for the playing
lines or for applied surface color
coatings. Any method that supplies
additional water is most effective for
curing.
Details
Net posts must be firmly anchored as shown in Figure 4 to resist
frost heave and the tension of the
net. The center tiedown of the net
requires firm anchorage as shown in
Figure 4.
Fence posts should be set in concrete foundations with an expansion joint material isolating them
from the concrete slab to pre ve n t
cracking from thermal changes,
drying shrinkage and frost heave.
PUBLICATION #C770317
Copyright © 1977, The Aberdeen Group
All rights reserved