Feature Article - July/August 2006
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Special Supplement: Complete Guide to Sports Surfaces and Flooring

Something's Afoot

By Kara Spak



Playground Help

When building a playground, the surface material can be the single most critical element in preventing injuries. Here are some pros and cons of potential surface materials, courtesy of the U.S. Consumer Product Safety Commission's Handbook for Public Playground Safety.

Organic loose material (wood chips, bark mulch, engineered wood fibers, etc.)

Fall-absorption:

  • Cushioning effect is dependent on the air trapped within and between the individual particles.
  • Also, you need an adequate amount in place to guarantee the proper cushioning effect.

Installation/maintenance:

  • Don't install over concrete.
  • This material requires some sort of container or barrier to keep it in place.
  • You also need good drainage, periodic replacement of material and continuous maintenance to keep the appropriate depth and remove potentially dangerous foreign substances.

Advantages:

  • Low initial cost
  • Easy to install
  • Good drainage
  • Less abrasive than sand
  • Less attractive to cats and dogs than sand
  • Looks good
  • Easily available

Disadvantages:

  • Rainy weather, freezing temperatures or high humidity can dampen the cushion.
  • Combines with dirt or foreign materials over time, which makes it a harder surface
  • Decomposes, pulverizes and compacts over time, requiring replenishment
  • Depth can be reduced both by the wind and by children's play.
  • Can be blown or thrown into children's eyes
  • Can by subject to microbial growth when wet
  • Hides trash like glass, nails and other sharp objects as well as animal excrement
  • Can be flammable
  • Subject to theft by neighborhood residents looking for cheap mulch

Inorganic loose material (sand and gravel)
Sand
  • Spreads easily outside of containment area
  • Small particles bind together and become less cushioning when wet.
  • When totally wet, sand becomes rigid.
  • May be tracked out of play area on shoes. Sand can be abrasive to some indoor floor surfaces and plastic.
  • Adheres to clothing
  • Attractive to animals
Gravel
  • Hard to walk on
  • Could present a fall hazard if displaced onto nearby hard surface
  • Hard pan can form under heavily trafficked areas

Installation/maintenance:

  • Don't install over hard surfaces like asphalt and concrete.
  • Needs to be contained by a device like a barrier wall or excavated pit
  • Good drainage required
  • Requires periodic renewal or replacement and continuous maintenance like grading, raking or sifting to keep the appropriate depth and to remove any foreign materials
  • Compacted sand should be turned over, loosed and cleaned periodically.
  • Gravel may require periodic break up and removal of hard pan.

Advantages:

  • Low startup cost
  • Easy to install
  • Does not pulverize
  • Not ideal for microbial growth
  • Nonflammable
  • Materials are abundant
  • Not susceptible to vandalism except by contamination
  • Gravel is less attractive to animals than sand.

Disadvantages:

  • Rainy weather, high humidity or freezing temperatures can reduce the cushioning potential.
  • Dirt and foreign materials combine with the material during normal use.
  • Sand can be blown by the wind or thrown into children's eyes.
  • Depth can be reduced by displacement.
  • May be swallowed
  • Conceals animal excrement and small but dangerous trash items like broken
  • glass or nails

Inorganic loose material (recycled-rubber nuggets)

Installation/maintenance:

  • Don't install over existing hard surfaces like concrete or asphalt.
  • Needs a method of containment like a retaining barrier or excavated pit
  • Good drainage required underneath material
  • Requires continuous maintenance like leveling, grading and raking to keep the appropriate depth and remove any foreign matter

Advantages:

  • Easy to install
  • Has superior shock-absorbing capability
  • Is not abrasive
  • Less likely to compact than other loose-fill materials
  • Not ideal for microbial growth
  • Does not deteriorate over time

Disadvantages:

  • Is flammable
  • Can cause soiling of clothes if untreated
  • May contain steel wires from steel-belted radial tires, though some manufacturers guarantee wire-free material
  • Depth may be reduced by displacement by children's play.
  • Can be swallowed

Unitary synthetic materials (rubber or rubber over foam mats or tiles, poured-in-place or urethane and rubber compositions)

Installation/maintenance:

  • Some unitary materials can be laid directly on hard surfaces such as asphalt or concrete. Others may require expert under-surface preparation and installation by the manufacturer or a local contractor. Materials generally require no additional means of containment.

Advantages:

  • Low-maintenance
  • Easy to clean
  • Consistent shock-absorbency
  • Material is not displace by children during play activities.
  • Generally low life-cycle costs
  • Good footing (depends on surface texture)
  • Harbors few foreign objects
  • Generally no retaining edges needed
  • Is accessible to the handicapped

Disadvantages:

  • Initial cost relatively high
  • Under surfacing may be needed for thinner materials.
  • Often must be used on almost level uniform surfaces
  • May be flammable
  • Subject to vandalism
  • Full rubber tiles may curl up and cause tripping.
  • Some designs are susceptible to frost damage.

Source: U.S. Consumer Product Safety Commission