Here is the search for pre-established spaces such as disused warehouses and pavilions that guarantee the 7 meters high free mandatory in each field.
For the construction of fields covered from scratch, the types of coverage that have long been used in sports facilities are met: the tension structure and the aerial structure.
Today manufacturers specialize in creating structures with thoughtful measurements and construction details ad hoc for paddlebut the types are the known ones.
The birth of this roofing system is due to the need to cover, in the industrial sector, large surfaces without particular comfort problems. That is why, in the sports sector, the pressure ball was initially used seasonal coverage of outdoor sports fields (mainly tennis courts).
Subsequently, however, the deck of the pressure switch found a wider use for a whole series of sports facilities in which the cost of the deck had to be kept as low as possible. It must be said at once that this is one of the best paddle tennis courts less common solution compared to the traction structure.
The fundamental characteristic of the roofs of the pressure switches is given by the lack of a real support structure, which is in fact replaced by the air that is kept inside with a slight overpressure (approximately 1/500 of the atmosphere ).
Air is introduced into the deck through wind sleeves connected to double-suction centrifugal fans placed outside.
The air exchange thus obtained is equal to approximately two or three total changes in the internal volume per hour.
In addition to the air and the systems that introduce it to the roof, the second important element of the pressure switch cover is precisely the roof. It is its size and shape that, thanks to the overpressed air, determine the shape of the volume thus covered.
The fabric that supports the cover is polyester.
The fabric is then coated with PVC to make it completely waterproof.
Additives are also added that guarantee premature yellowing, hardening and cracking over time. A special additive is also added to make the foil automatically extinguish.
To prevent condensation on the soffit, and to improve its thermal efficiency, the sheet can be double-sided, with an air space that acts as an insulator between the two layers.
The anchoring of the sheet to the ground can occur in different ways; however, it must transmit to the ground the tensions derived from the internal overpressure of the roof and also from the wind, and in addition ensure good airtightness between deck and ground.
When the pressostatic “ball” has to cover several aligned paddle courts, the curb must be of an appropriate size as the loads increase, that is, the vertical tensile forces. For example, the anchorage edge of a canvas covering four tennis courts must have a weight per linear meter of at least 1,100 kg.
Since the load-bearing structure of a pressure switch shed is made through the air or rather by fans that maintain a slight overpressure inside, the ventilation system must be completely reliable.
But that is not enough. Sometimes it may be necessary to have a small emergency system that comes into operation in all those cases where the main system is blocked (power failure, breakdown, etc .; see the example of the roof of the Camogli pool).
The system described so far, which has undergone considerable development in recent decades, especially as a roof for tennis courts, is, however, indicated in those cases in which an existing open system must be equipped with the possibility of being also used indoors, for example in bad season; or as a temporary structure pending the construction of a definitive covered system.
The other system of “light” coverage. consists of the sheet used in combination with roof structures made of steel by means of arches or reticular portals.
A series of parabolic arches or rectilinear segments, placed at specific distances (from 3 to 7/8 meters) act as a support for the sheet metal roof that can be placed on both the soffit and the extradose. of the same arches. The foil participates in achieving system stability. In fact, on the sheet itself, transversely to the plane of the parabolic arch, some ropes are fixed which, starting from the ground on the sides of the head, rise together with the sheet and, thus, will be progressively connected to all arcs.
Therefore, by means of their correct tension, they act as reinforcing elements and system-wide hardening. To increase the rigidity of the arches, they can be built with variable geometry to reach the ground with the two sides of the lower lattice widened for a firmer support to the ground. The anchoring is done by means of the screws of the beams on steel supports anchored to reinforced concrete plinths that emerge from the ground.
An advantage of these systems, compared, for example, with pressure static roofs, is that they largely release the tissue from structural functions. This is how it is possible to create large windows on the sides of the fabric, without special difficulties; or even pull out the cloth to a certain height they allow better ventilation interior and a better and more comfortable interior / exterior relationship during the summer season.
This same feature can make us understand the difference in use between the balloon and the sheet anchored to reticular arches. The hot air balloon is usually mounted at the beginning of the bad season and is disassembled in late spring, when the days are warm enough. The sports facility will be, then fully protected of atmospheric agents during the autumn and winter seasons, while during the summer season it will again be subject in all respects to climatic excesses. The cloth anchored to reticular arches, on the other hand, is a permanent structure.
In fact, if the assembly of these structures is very fast also by the ease of prefabrication, the disassembly and the seasonal assembly of the arches and of the sheet is unthinkable; at most can be lifted, as already mentioned, the cloth for a height of two to four meters. With these systems, therefore, stable roofs are created that, depending on the weather conditions, can increase or decrease from time to time the closure and protection of the internal environment with respect to the outside.
A slight advantage in the operating costs of the sheets supported by reticular arches, compared to the covers of the pressure switches, is represented by a modest consumption savings energetic. In fact, it is not necessary to keep a number of fans running all the time to maintain internal overpressure.
Also in this case the room is heated by a hot air generator placed outside.
Instead of metal arches, the load-bearing structure of the roof sheet can be made up of laminated wood beams.
The particularities of the wood are the lightness and the excellent thermal and soundproofing qualities. The realization of beams or any other structure bearing by gluing and pressing wooden slats with opposite vein (in fact this is the procedure that is followed for the realization of lamellar structures) also has the faculty to increase considerably, and especially to guarantee, the constancy of efficiency of the structure regarding the resistance to compression and traction.
This means, on the one hand, a reduction in the sections needed to withstand loads, and on the other hand, the possibility of designing sections and section shapes of structures that are extremely difficult to find in nature. In fact, with laminated wood beams of considerable section height, up to two meters, are also used.
Statically the most common systems are the beam bent on two supports, the arch with three hinges, the portal with three hinges, the portal with two hinges. Beams bent over two supports can reach lights of 40 meters and a structural height of approximately 0.07 times the light.
They are not required to cover paddle courts high-thickness structures, also taking into account that the sheet does not carry a high load of its own to support. However, structural engineering must be carried out specifically for the dimensional needs of this sport.
Since the sequence of the most used lamellar structures (beams, arches, portals) are independent of each other within the same building, the structures themselves will be hardened to increase the absorption capacity of the forces for the kinetic action of the wind.
To this end, the support frame of the roof is already made ineffective reinforcement action which can sometimes be improved by the addition of diagonally laid steel cables to further harden the system. All carpentry will be made of steel, adequately protected against corrosion.