FOUNTAINS & SWIMMING POOLS - 3
This form of concrete and also the method
is often referred to as
Gunite. Strong, watertight pools can
be made by this process when
it is carried out by skilled workmen.
Nevertheless, it is nowhere
near so widely used as the traditional
method of pouring the concrete
in forms. Since much of the cost of building
a swimming pool is due to
the fact that the walls must be strong
enough to resist the pressure
of the earth upon them when the pool
is empty, many attempts to
lower the cost have been made by changing
the traditional pool
shape. All engineers know that if the
walls of a buried structure
such as a pool have the shape of a hemisphere,
they can be made
much lighter because a thrust at any
point on the outer surface
tends to be resisted by a considerable
part of the structure. Accord-
ingly some pools have been built in this
shape or in shapes that lie
between it and the conventional box shape.
Also pools have been lined with other
materials such as brick,
stone, and composites bound with asphalt.
The catch in attempting
to lower the cost of pool construction
by using other materials is
that few building materials which are
adequate at all cost as little as
concrete. When a pool is made of brick
or stone laid up in mortar,
it is always necessary to apply waterproofing
material to the inside
of the walls. Steel reinforcing may be
required unless the walls are
extraordinarily massive. A great many
experiments have been made
along these lines, and a few builders
have successfully built a fair
number of pools in their communities
at prices somewhat lower than
the pools would cost if built by traditional
methods. Nevertheless,
in spite of all the experiments no method
has yet seriously chal-
lenged the standard one of building pools
in the shape of an oblong
box with straight sides, nor does any
material yet threaten the supremacy
of poured concrete. Private outdoor swimming
pools range in size from those
which are too small for pleasurable swimming
to pools of the same
dimensions as are built for swimming
contests. Swimming pools on
home sites have been built in the following
lengths and widths (and
probably also in others), the measurements
being given in feet:
16 x 30 20 x 60
18 x 36 25 x 60
16 x 40 30 x 75
20 x 40 32 x 64
Depths vary also. Most pools are graduated
in depth. The depth of the
water at the deepest part, directly over
the drain, is usually 8 ft.,
6 in. or 9 ft. The depth at the deeper
end ranges from 6 ft., 6 in. to 7 ft.,
6 in., and the
depth at the shallow end is usually 3
ft., 6 in. or 4 ft, the diving
board should be placed so that the diver
will escend into deep water. Three feet,
6 in. is a little too deep for small
children, especially children who are
just learning to swim.
Some families with small children prefer
to build a separate swimming pool for
them. The depth of the water in children's
pools should run from about 24 to 36
in. Wading pools for children should
not be more than 15 in. deep.
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