Sport facility surfacings in comparison – what is suitable where?
Sports grounds need to be such that they enable users to practice their preferred form of sport with enjoyment and comfort. To ensure this is the case, use of the correct form of surfacing is essential. However, it is by no means easy to determine what form of surfacing is appropriate for sites that are used for a variety of different activities. In the following, we provide an overview of all the standard types of sports ground surfacings and compare their various characteristics.
Of course, for many types of sports there are clear requirements that determine what forms of surfacing are suitable and also specifications that apply to their corresponding composition. But outside the world of professional sport, it is possible to undertake various activities on different forms of surfacing. We have put together in the following a comparison of the standard forms of sports ground surfacings in terms of their structure, relevant standards, utilisation factors, price, maintenance, risk of injury, durability, resistance to weathering and ecofriendliness.
Natural grass
Structure: The grass is either sown or laid in the form of turfs on a substrate (thickness approx. 80 - 120 mm) consisting of soil, sand and water-retaining materials with, if necessary, a drainage layer (where the groundwater table is near the surface and water-permeability is poor). In the case of sown grass, a suitable seed blend (such as German RSM) should be used for sport surfacings and the depth of growth above ground should not be allowed to exceed 5 mm. The surface should then be ready for use - depending on rate of growth of the grass used - roughly 2 months later. A hard-surfaced (grey-green) area can be resurfaced with grass assuming that the drainage is still functioning. If laying turfs, these should be placed on the wetted surface of the bearing substrate. A turfed surface should be ready for use 3 - 5 weeks after installation.
Relevant standard: DIN 18035-4 Sports grounds - Part 4: Sport turf areas
Utilisation factors: Various sources specify that natural grass surfaces will tolerate 400 - 800 playing hours annually. Hence, on fully natural grass surfaces, the corresponding figure is likely to be in the region of 500 hours and probably somewhat more on grey-green areas resurfaced with grass. However, it must be borne in mind that natural grass surfaces will require periods in which to recover, particularly after extensive use and following exposure to extreme climatic conditions (snow, persistent rain, drought). Natural grass surfaces are generally used for soccer, rugby and American football pitches and light athletics activities, such as throwing events. Because of its sensitivity, this form of surfacing is not fully suitable for use in connection with mass sports activities.
Price: Depending on type and quality, it will cost roughly €150,000 - 250,000 to install a grassed surface. Ensure that any quote includes the costs of the provision of drainage and sprinkler systems.
Maintenance: Natural grass surfaces require considerable maintenance. They need to be regularly mowed, aerated, fertilised, re-seeded etc. The costs of reasonable maintenance are in the range €4 - 5 per square metre; in the case of a standard-sized soccer pitch, this would be equivalent to €30,000 - €35,000 per year.
Risk of injury: Natural grass provides a relatively safe form of surfacing; it will cushion falls and is not associated with an increased risk of injury. However, if the surface is poorly maintained, there will be gaps in the grass covering and inappropriate intergrowth that could enhance the possibility of injury.
Durability: If a natural grass surface is appropriately maintained, it will in theory remain usable in perpetuity. Heavily used areas, such as those around goalmouths, will need regular reseeding (recovery period). It may also be necessary to returf the area, but there are no guidelines as to when and whether such measures are necessary. A grassed surface is renewed several times a year when it is used for professional sports activities.
Resistance to weathering: Natural grass surfaces are very sensitive to the weather. Variable weather conditions, with mild summers and winters, are best for them but - of course - this is outside the control of the sports ground operator. Following snowfall and after heavy rain, a grass-surfaced sports ground should not be used. The surface will require frequent watering in dry and hot summers - the playing surface will be considerably impaired by exposure to high temperatures.
Ecofriendliness: Natural grass surfaces are of their nature very ecofriendly, although this may not apply to the measures required for their upkeep and maintenance. Fertilisers and pesticides can contaminate the soil and environment while motorised vehicles are often used for their care. Disruptive natural elements, such as pest insects, weeds and moles, need to be kept at bay to maintain a good playing surface quality - this will necessitate the use of techniques that are not necessarily ecofriendly.
Artificial grass
Structure: Artificial grass is laid in the form of filled or unfilled systems on an elastic substrate or layer (unconnected with a levelling layer) on a suitable undersubstrate. Used for the infill of artificial grass systems are quartz sand and granules. There are various types of granules - from SBR granules made of old car tyres, through granules made of EPDM and TPE to cork. Unfilled artificial grass is laid directly on an elastic layer. Artificial grass surfaces need appropriate drainage. The site can usually be made available for use shortly after installation.
Relevant standard: DIN 18035-7 Sports grounds - Part 7: Synthetic turf areas
Utilisation factors: An artificial grass surface will tolerate 2000 - 2400 playing hours annually. There is no need to provide for recovery periods; any snowfall should be removed from the surface before use. Filled artificial grass surfaces are generally used for soccer, rugby and American football pitches while unfilled systems are in standard use for field hockey pitches although there are also forms that have been developed for use on soccer pitches. Many forms of amateur sports are possible on artificial grass surfaces because of the excellent resilience the game of padel which is particularly popular in Spain is played on artificial grass courts.
Price: The cost of installation of a new artificial grass surface, including drainage, is in the region of €500,000 although this can be somewhat more if the better quality systems are employed. Some €250,000 will need to be spent to renew an artificial grass surface.
Maintenance: Despite many claims to the contrary, an artificial grass surface does require maintenance. Any superficial soiling needs to be removed, the filling will need to be regularly loosened, and a deep-clean should be carried out once or twice a year to ensure that the filling material is also washed. The quality of upkeep will determine the durability of the surface. The costs of suitable maintenance are in the range €3 per square metre; in the case of a standard-sized soccer pitch, this would be equivalent to €20,000 per year. Some experts advise regularly watering an artificial grass surface – especially when temperatures are high, this will have the effect of cooling the pitch.
Risk of injury: It was long considered that artificial grass surfaces were associated with a high level of injury but modern artificial grass systems are now as safe as natural grass surfaces. There is no increased risk of injury. As the speed of play on artificial grass surfaces depending on type of sport can be very fast, injuries can occur particularly when the surfaces are wet, but any injury would not be attributable to the nature of the surface per se. An artificial grass surface can become quite hot during warm weather, but thanks to the recent improvements in the related technologies and assuming the surface is watered, there is no risk of it burning skin on contact.
Durability: If properly maintained, an artificial grass surface can be used for up to 15 years after which it is advisable to renew it. Earlier renewal can often be necessary because of the general low level of upkeep. As renewal will cost some €250,000, this factor and the provision of suitable maintenance measures need to be taken into account in the planning phase.
Resistance to weathering: The weather-resistance of artificial grass surfaces is excellent. Rain and wet have no effect on these surfaces. It is advisable to water them during warm weather to ensure that they do not become too hot. But modern artificial grass technology means these are now less problematic - the granules can be the main issue. Artificial grass surfaces can be readily used in winter, although any snow and ice needs to be removed beforehand.
Ecofriendliness: In environmental terms, artificial grass surfaces are not ideal. The disposal of old surfaces on renewal requires their incineration or their dumping in landfill sites. There are some options for recycling being developed but these are not fully serviceable in all situations yet. Another problem is the risk of release of microplastics and PAH from SBR granules and that of the escape of granules into groundwater.
Hybrid grass
Structure: In the case of hybrid grass systems, either woven artificial grass mats are incorporated in a natural grass surface or blades of artificial grass are inserted in the turf bearing layer. It is also possible to retrospectively plant artificial grass fibres in a natural grass surface. Otherwise, the structure is very similar to that of a natural grass surface.
Relevant standard: As this concept is still relatively new, this aspect is still unclear but DIN 18035 is generally applicable.
Utilisation factors: Information varies but as a rule the number of playing hours will increase when incorprating a hybrid grass surface system into a natural grass surface. Depending on the system, quoted figures are in the range 1200 playing hours per year. Hybrid grass surfaces are frequently used for soccer, rugby and American football pitches. In facilities used for amateur sports, however, the more resilient artificial grass or synthetic surfacings are more commonly employed.
Price: The installation of a hybrid grass surface costs slightly less than that of an artificial grass surface; the quoted figure is some €400,000. Of course, costs will be considerably less if a hybrid grass system is used to only reinforce the penalty areas and centre circle only of an existing pitch. Costs also vary in accordance with the various types of hybrid systems available.
Maintenance: The outgoings in this connection will be roughly the same as for a natural grass surface. Although the surface will not so rapidly become worn, particular care (and in some cases special tools) will be needed for much of the maintenance of the natural grass elements.
Risk of injury: Difficult to determine; it is possible that as the system is more stable, there is less risk of injury on a hybrid surface than on a natural grass surface.
Durability: It is also not possible to specify how long a hybrid system will remain serviceable. Research is still on-going. Assuming that the natural grass elements are well maintained, this will be many years or as long as the hybrid system is usable. But durability should be equivalent to that of an artificial grass surface.
Resistance to weathering: One of the major advantages of the hybrid systems is that they provide a natural grass surface with increased resistance to weathering, particularly where there is exposure to heavy rainfall.
Ecofriendliness: Research is still trying to establish what effects hybrid systems have on the environment. The artificial elements incorporated in the natural grass surface could be problematic as could be their disposal.
Cinder surfaces
In this case, the surfacing consists of a tamped granular, non-bonded blend of mineral particles. Various layers make up the structure; at the bottom there is often a filter layer, on top of this a bearing layer, then an elastic layer and the cinder surface of natural or waste mineral granules. The granule composition must conform to the specifications of the DIN standard and must also be water-permeable. A cinder surface may require up to a year after installation before it is usable, depending on climatic conditions and the moisture content of the soil.
Relevant standard: DIN 18035-5 Sports grounds - Part 5: Tamped surfaces
Utilisation factors: Once upon a time, cinder surfaces were in standard use for soccer pitches, running tracks and amateur sports facilities in Germany. In principle, many different kinds of sports can be practised on such surfaces although they do not provide ideal playing surfaces for most such activities. Cinder-surfaced facilities are a dying breed - those practising sports prefer to avoid them and very few new cinder-surfaced pitches are being installed because of the availability of more popular alternatives. These surfaces will tolerate some 1200 - 1500 playing hours per year.
Price: The cost of installation of a cinder surface, including drainage work, is in the region of €200,000 – €220,000.
Maintenance: A cinder surface must be regularly stripped and the surfacing requires regular upkeep. The upkeep costs at €1- 2 per square metre are, on the whole, far lower than the corresponding costs for other forms of surfacing. However, the actual cost will be determined by how frequently the surface needs maintenance. Most existing cinder surface pitches and courts are largely neglected in this connection.
Risk of injury: Although good cinder surfaces should provide impact protection, falling on them can have unpleasant consequences. This can result in abrasions on unprotected knees and elbows with foreign particles embedded in the wounds. There is thus the risk of infection. Although the speed of play on cinder surfaces tends to be slower than on grass surfaces and users tend to be more careful for reasons of self-protection, there is still a higher risk of injury.
Durability: Assuming drainage is functional and the surface is well maintained, such a surface can remain usable for several decades.
Resistance to weathering: Heat and cold have little effect on a cinder surface; its main enemy is rain. Such a surface can be used on the whole when damp; when waterlogged or during a frost thaw phase, use should be avoided. Heavy rainfall can also wash away a cinder surface so that the area becomes very hard and the risk of injury is increased.
Ecofriendliness: The materials used for surfacing are often contaminated with heavy metals, leading to problems with disposal. Dioxin-polluted dust can be a threat to the health of users; levels of such contaminants need to be regularly monitored.
Artificial surfaces
Structure: These are made from water-permeable or -impermeable, multilayered, bonded materials, usually sited on layer of asphalt that is positioned on an unconnected bearing layer.
Relevant standard: DIN 18035-6 Sports grounds - Part 6: Synthetic surfaces
Utilisation factors: There are many different variants and forms of artificial surfaces that can be used for sports. They have been used for decades for light athletics activities in the form of tartan tracks. Many multisport and amateur sport facilities employ artificial surfaces. Synthetics are used in particular for surfaces for outdoor basketball courts and other types of sports in which it is desirable that the ball should bounce well from the ground.
Price: The materials alone required for an artificial surface cost some €20 - €40 per square metre. That would be equivalent to €200,000 for a more extensive light athletics track. In addition to this there are also the costs of putting in place the substrate and of installation.
Maintenance: An artificial surface is relatively low-maintenance but does need to be cleaned regularly. In addition, its drainage capacity needs to be monitored.
Risk of injury: As a rule, artificial surfaces provide good impact protection and thus are unlikely to cause injuries. However, they can differ greatly in terms of quality. Not only that, but the climatic conditions and the type of activity itself can determine to a large extent the possibility of injury.
Durability: This depends mainly on quality and the extent to which the material is subject to wear. Assuming these factors conform to requirements, a surface will remain usable over many years. At the same time, damage due to vandalism can be a problem in facilities that are open to the public.
Resistance to weathering: Artificial surfaces are in general resistant to weathering. They can become very hot in warm weather but at the same time good surfaces should not melt or become warped on exposure to radiation from the sun - but this is again an aspect that is determined by quality.
Ecofriendliness: The issue here is again disposal. There are not many ways of recycling the material. Microplastics can also be released due to the wear of artificial plastic surfaces.
Sand surfaces
Structure: This involves the installation in the ground of a plastic trough with a depth of some 40 cm. Assuming the soil layers underneath are not water-permeable, a drainage layer will be required. A substrate of gravel is covered with quartz sand with rounded grain that has a diameter of 0.063/2 mm.
Relevant standard: There is no specific standard but guidelines are provided by various parts of the standards for sport grounds and playgrounds.
Utilisation factors: Mainly used for beach volleyball - but can also be used for variants of tennis, soccer, badminton etc. These surfaces are generally used in the six months from April to October.
Price: The sand costs approx. €15 per tonne; some 200 tonnes sand are required for a beach volleyball field and including the transport this costs roughly €4000. The rough cost of the gravel and other materials required is €7000. It is necessary to add to this the expense of installation (and provision of drainage where necessary). On the whole, the nature and size of the facility will determine the cost.
Maintenance: The sand needs to be regularly cleaned (at least once every 12 months) and must also be renewed for reasons of hygiene. Costs here are dependent on method used and extent of work required.
Risk of injury: It is unlikely that falls on this kind of surface will result in any form of serious injury. It is safe to play on because users cannot move too rapidly on it and it will cushion impacts. At the same time, it must be borne in mind that pathogens can sustain themselves quite happily in sand and will be active here longer than they are, for example, in water.
Durability: Assuming the sand is regularly renewed and drainage continues to be effective, such surfaces can be used for decades.
Resistance to weathering: Sand surfaces should be used for sports activities only when they are dry.
Ecofriendliness: Assuming the sand is not contaminated, such a surface is very environmentally-friendly.
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