The protective surface underneath backyard playsets is often a forgotten element of backyard playground safety. While approximately 80% of public playgrounds have some type of shock-absorbing protective surfacing under playground equipment, only 9% of home backyard playgrounds do, according to a 2001 playground injury study conducted by the U.S. Consumer Products Safety Commission (CPSC). The study found that, of the approximately 50,000 injuries per year associated with home backyard playground equipment, 69% of the injuries were a result of falls to a non-protective surface under the equipment.
The most frequently used backyard playground surface options are grass and dirt, but neither surface adequately protects children against serious injury due to falls, even falls that occur from 30 inches or less above the ground. Fractures of the arms and hands, and cuts and bruises of the head and face are the most commonly reported injuries that result from a child falling from playground equipment to a non-protective playground surface such as grass or dirt, as reported by the CPSC.
The good news is that a variety of protective surfaces exist that can fulfill a homeowner's need for playground safety. Naturally, playground surface options range in cost from reasonable to pricey, and each option has its own list advantages and disadvantages. Considering the advantages and disadvantages of each type of playground surface material, as presented in this article, should allow you to choose the most suitable playground surface for your backyard playground.
The first and most vital piece of information to know before selecting a material to use for your protective playground surface is the critical height of the playground equipment. Critical height refers to the "maximum fall height from which a life-threatening head injury would not be expected to occur." The critical height of your playground equipment equals the height (in feet) of the uppermost portion of your backyard playground equipment that is accessible to children. The protective playground surface you decide on for your backyard playground should be installed with a depth that is appropriate for your equipment's critical height.
The following information details the critical height (in feet) for each of the loose-fill surface materials described in this article "when tested in an uncompressed state at depths of 6, 9, and 12 inches. The [information] also shows the critical height when a 9 inch depth of each material was tested in a compressed state." As an example, if the critical height of your backyard playground equipment is 8 feet, then your best options for protective loose-fill surface materials, according to the information below, would be 9 inches of compressed or uncompressed wood chips, 9 inches of uncompressed shredded bark mulch, 12 inches of uncompressed play sand, 12 inches of uncompressed pea gravel, or 6 inches of uncompressed recycled rubber mulch.
WOOD CHIPS*
- Six inch depth, uncompressed = 7 feet
- Nine inch depth, uncompressed = 10 feet
- Twelve inch depth, uncompressed = 11 feet
- Nine inch depth, compressed = 10 feet
*This product may also be referred to as Wood Mulch, but the term Wood Chips more accurately describes the product.
SHREDDED BARK MULCH
- Six inch depth, uncompressed = 6 feet
- Nine inch depth, uncompressed = 10 feet
- Twelve inch depth, uncompressed = 11 feet
- Nine inch depth, compressed = 7 feet
ENGINEERED WOOD FIBERS**
- Six inch depth, uncompressed = 6 feet
- Nine inch depth, uncompressed = 7 feet
- Twelve inch depth, uncompressed = >12 feet
- Nine inch depth, compressed = 6 feet
**This may also be referred to as Uniform Wood Chips, but, in the playground industry, the product is more commonly known as Engineered Wood Fibers.
FINE SAND
- Six inch depth, uncompressed = 5 feet
- Nine inch depth, uncompressed = 5 feet
- Twelve inch depth, uncompressed = 9 feet
- Nine inch depth, compressed = 5 feet
COURSE SAND
- Six inch depth, uncompressed = 5 feet
- Nine inch depth, uncompressed = 5 feet
- Twelve inch depth, uncompressed = 6 feet
- Nine inch depth, compressed = 4 feet
FINE GRAVEL
- Six inch depth, uncompressed = 6 feet
- Nine inch depth, uncompressed = 7 feet
- Twelve inch depth, uncompressed = 10 feet
- Nine inch depth, compressed = >6 feet
MEDIUM GRAVEL
- Six inch depth, uncompressed = 5 feet
- Nine inch depth, uncompressed = 5 feet
- Twelve inch depth, uncompressed = 6 feet
- Nine inch depth, compressed = 5 feet
SHREDDED TIRES***
- Six inch depth, uncompressed = 10-12 feet
- Nine inch depth, uncompressed = N/A
- Twelve inch depth, uncompressed = N/A
- Nine inch depth, compressed = N/A
***This data is from tests conducted by independent testing laboratories on a 6 inch depth of uncompressed shredded tire samples produced by four manufacturers. The test results reported critical heights which varied from 10 feet to greater than 12 feet. It is recommended that persons seeking to install shredded tires as a protective surface request test data from the supplier showing the critical heights of the material when it was tested in accordance with ASTM F1292.
Alternatives to loose-fill surface materials are rubber playground tiles, rubber mats, and poured-in-place playground surfaces. These options are available from a number of manufacturers who may use a variety of shock-absorbing materials. The manufacturers should be able to provide you with test data that shows the critical height for the protective surfaces they offer.
Appreciating some of the advantages and disadvantages of loose-fill surface materials should assist you in narrowing the choices to meet your particular situation. In general, loose-fill playground surface materials like wood chips, shredded bark mulch, pea gravel, play sand, and recycled rubber mulch are most often chosen for backyard playgrounds because they are affordable and easy to find at a local garden center or home improvement warehouse. Recycled rubber mulch can also be found in a variety of colors and sizes through internet suppliers.
LOOSE-FILL MATERIALS - GENERAL GUIDELINES
A retaining barrier of some kind is required to keep the surface materials from becoming displaced as a result of active play or weather conditions. Also, loose-fill materials should never be installed on top of hard surfaces like concrete or asphalt. Finally, good drainage beneath the protective surface is highly recommended.
Overall Advantages:
- The initial cost of installing a loose-fill playground surface under your backyard playground equipment is generally low because the materials are easy to find and are relatively inexpensive.
Overall Disadvantages:
- Over time, loose-fill materials can become compressed, thus lowering their protective capabilities.
- Recommended depths become compromised when active play or windy conditions displace the loose-fill materials.
- Debris such as broken glass, nails, and other sharp objects which can cause injury can be easily hidden by loose-fill materials.
- Ongoing upkeep is essential to maintain proper depth and to remove debris. Maintenance can include raking, sifting, grading, and leveling.
- Periodic renewal or replacement of loose-fill materials is required, which can require more time and money than expected. The exception to this is recycled rubber mulches - see below for more detail.
WOOD CHIPS AND SHREDDED BARK MULCH
Advantages:
- Wood chips and shredded bark mulch are not as abrasive as play sand.
- Animals are less likely to foul wood chips and shredded bark mulch.
- Wood chips and shredded bark mulch are appealing to the eye.
Disadvantages:
- The protective ability of wood chips and shredded bark mulch is reduced in rainy, humid, and freezing weather conditions.
- Over time, wood chips and shredded bark mulch will become crushed, compacted, and will decompose.
- Wood chips and shredded bark mulch can develop fungus and mold when wet.
- Insects are drawn to wood chips and shredded bark mulch.
PEA GRAVEL
Advantages:
- Pea gravel will not become ground down and decompose.
- Mold and fungus growth is not generally a concern.
- Animals and insects are less attracted to pea gravel.
Disadvantages:
- Pea gravel can be hard to walk on.
- The protective ability of pea gravel is reduced in rainy, humid, and freezing weather conditions.
- Pea gravel can be a falling hazard if displaced from the playground area to a nearby hard surface (sidewalk, decking, or patio, for example).
PLAY SAND
Advantages:
- Play sand will not become crushed and decompose.
- Mold and fungus growth is not generally a problem.
Disadvantages:
- Play sand can be hard to walk on.
- The protective ability of play sand is reduced in rainy and humid weather conditions.
- Animals are attracted to sand unless it can be covered when not in use.
- Play sand adheres easily to shoes, clothing, and skin.
- Play sand can be abrasive to floor surfaces if tracked inside.
RECYCLED RUBBER MULCH
Advantages:
- Recycled rubber mulch does not generally need to be replaced or renewed each year. Many manufacturers claim that rubber mulch can last approximately 50 years without requiring replacement. Check with recycled rubber mulch suppliers for any guarantees or warrantees that may be available.
- Rubber mulch tends to be cleaner and less likely than other loose-fill materials to produce dirty clothing, hands, and shoes during active play.
- Does not cause scrapes, scratches, or splinters from falls.
- Animals and insects are not attracted to rubber mulch.
- Mold and fungus growth is not a problem.
Disadvantages:
- Recycled rubber mulch may need to be raked periodically to maintain appropriate depths in high traffic areas.
- Colors on recycled rubber mulch may fade over time.
OTHER PROTECTIVE PLAYGROUND SURFACE OPTIONS
Rubber tiles, rubber mats, and poured-in-place surfaces are initially more expensive surface options than loose-fill materials, but they usually require very little maintenance over time. To determine whether one of these options would be more cost effective than a loose-fill material, consider how many children might potentially use your backyard playground equipment and for how many years. Larger families, for example, may prefer to pay more initially for a surface that will be easier and much less expensive to maintain throughout many years of active play.
Advantages:
- No means of containment is usually required.
- Surfaces are accessible by wheelchairs and easy to walk on.
- Displacement of materials is not an issue, so the protective ability of these surfaces stays consistent even in high traffic areas.
- Surfaces need very little upkeep over time and are easy to clean.
- Debris such as broken glass and other sharp objects which can cause injury are not easily buried by these surfaces.
- Animals and insects are not attracted to the surface materials.
- Mold and fungus growth is not a problem.
Disadvantages:
- The area under the surface usually requires special preparation. Contact the manufacturer or supplier for details.
- Surfaces may require professional installation.
- Rubber tiles may curl and become tripping hazards if not installed correctly.
- Some surfaces may be damaged by frost.
In sum, no protective playground surface of any type or depth can prevent all injuries. Nonetheless, installing a protective playground surface as the foundation for your backyard playground equipment is crucial for increasing playground safety. The most suitable playground surface for your needs is up to you, but whatever choice you make will be a significant step toward protecting the children who use your playground equipment from serious injuries due to falls to the surface.
Sources:
CPSC Document 323. "Home Playground Safety Tips."
CPSC Document 324 "Outdoor Home Playground Safety Handbook." 2005.
CPSC Document 1005. "Playground Surfacing Materials."
CPSC Report. "Home Playground Equipment-Related Deaths and Injuries." July 2001.
CPSC Report. "Special Study: Injuries and Deaths Associated with Children's Playground Equipment." April 2001.
