2.4 Surfacing
The surfacing under and
around playground equipment
is one of the most
important factors in reducing
the likelihood of life-threatening
head injuries. A fall
onto a shock absorbing surface
is less likely to cause a
serious head injury than a fall onto a hard surface. However,
some injuries from falls, including broken limbs, may occur
no matter what playground surfacing material is used.
The most widely used test method for evaluating the shock
absorbing properties of a playground surfacing material is to
drop an instrumented metal headform onto a sample of the
material and record the acceleration/time pulse during the
impact. Field and laboratory test methods are described in
ASTM F1292 Standard Specification for Impact Attenuation of
Surface Systems Under and Around Playground Equipment.
Testing using the methods described in ASTM F1292 will
provide a “critical height” rating of the surface. This height
can be considered as an approximation of the fall height
below which a life-threatening head injury would not be
expected to occur. Manufacturers and installers of playground
protective surfacing should provide the critical
height rating of their materials. This rating should be greater
than or equal to the fall height of the highest piece of equipment
on the playground. The fall height of a piece of equipment
is the distance between the highest designated play
surface on a piece of equipment and the protective surface
beneath it. Details for determining the highest designated
play surface and fall height on some types of equipment are
included in §5 Parts of the Playground.
2.4.1 Equipment not covered by protective
surfacing recommendations
The recommendations for protective surfacing do not apply
to equipment that requires a child to be standing or sitting at
ground level. Examples of such equipment are:
• Sand boxes
• Activity walls at ground level
• Play houses
• Any other equipment that children use when their feet
remain in contact with the ground surface
2.4.2 Selecting a surfacing material
There are two options available for surfacing public playgrounds:
unitary and loose-fill materials. A playground
should never be installed without protective surfacing of
some type. Concrete, asphalt, or other hard surfaces should
never be directly under playground equipment. Grass and
dirt are not considered protective surfacing because wear
and environmental factors can reduce their shock absorbing
effectiveness. Carpeting and mats are also not appropriate
unless they are tested to and comply with ASTM F1292.
Loose-fill should be avoided for playgrounds intended for
toddlers.
Handbook for Playground Safety 8
2.4.2.1 Unitary surfacing materials
Unitary materials are generally rubber mats and tiles or a
combination of energy-absorbing materials held in place by a
binder that may be poured in place at the playground site
and then cured to form a unitary shock absorbing surface.
Unitary materials are available from a number of different
manufacturers, many of whom have a range of materials with
differing shock absorbing properties. New surfacing materials,
such as bonded wood fiber and combinations of loose-fill
and unitary, are being developed that may also be tested to
ASTM F1292 and fall into the unitary materials category.
When deciding on the best surfacing materials keep in mind
that some dark colored surfacing materials exposed to the
intense sun have caused blistering on bare feet. Check with
the manufacturer if light colored materials are available or
provide shading to reduce direct sun exposure.
Persons wishing to install a unitary material as a playground
surface should request ASTM F1292 test data from the manufacturer
identifying the critical height rating of the desired
surface. In addition, site requirements should be obtained
from the manufacturer because some unitary materials
require installation over a hard surface while others do not.
Manufacturer’s instructions should be followed closely, as
some unitary systems require professional installation.
Testing should be conducted in accordance with the ASTM
F1292 standard.
2.4.2.2 Loose-fill surfacing materials
Engineered wood fiber (EWF) is a wood product that may
look similar in appearance to landscaping mulch, but EWF
products are designed specifically for use as a playground
safety surface under and around playground equipment.
EWF products should meet the specifications in ASTM
F2075: Standard Specification for Engineered Wood Fiber and
be tested to and comply with ASTM F1292.
There are also rubber mulch products that are designed
specifically for use as playground surfacing. Make sure they
have been tested to and comply with ASTM F1292.
When installing these products, tips 1-7 listed below should
be followed. Each manufacturer of engineered wood fiber
and rubber mulch should provide maintenance requirements
for and test data on:
• Critical height based on ASTM F1292 impact attenuation
testing.
• Minimum fill-depth data.
• Toxicity.
• ADA/ABA accessibility guidelines for firmness and stability
based on ASTM F1951.
Handbook for Playground Safety
9
Appropriate Surfacing
• Any material tested to ASTM F1292, including
unitary surfaces, engineered wood fiber, etc.
• Pea gravel
• Sand
• Shredded/recycled rubber mulch
• Wood mulch (not CCA-treated)
• Wood chips
Inappropriate Surfacing
• Asphalt
• Carpet not tested to ASTM F1292
• Concrete
• Dirt
• Grass
• CCA treated wood mulch
Other loose-fill materials are generally landscaping-type
materials that can be layered to a certain depth and resist compacting. Some examples include wood mulch, wood
chips, sand, pea gravel, and shredded/recycled rubber mulch.
Important tips when considering loose-fill materials: 1. Loose-fill materials will compress at least 25% over time
due to use and weathering. This must be considered when
planning the playground. For example, if the playground
will require 9 inches of wood chips, then the initial fill
level should be 12 inches. See Table 2 below.
2. Loose-fill surfacing requires frequent maintenance to
ensure surfacing levels never drop below the minimum
depth. Areas under swings and at slide exits are more susceptible
to displacement; special attention must be paid
to maintenance in these areas. Additionally, wear mats
can be installed in these areas to reduce displacement.
3. The perimeter of the playground should provide a
method of containing the loose-fill materials.
4. Consider marking equipment supports with a minimum
fill level to aid in maintaining the original depth of
material.
5. Good drainage is essential to maintaining loose-fill
surfacing. Standing water with surfacing material reduces
effectiveness and leads to material compaction and
decomposition.
6. Critical height may be reduced during winter in areas
where the ground freezes.
7. Never use less than 9 inches of loose-fill material.
Shallower depths are too easily displaced and compacted.
8. Some loose-fill materials may not meet ADA/ABA accessibility
guidelines. For more information, contact the
Access Board (see §1.6) or refer to ASTM F1951.
9. Wood mulch containing chromated copper arsenate
(CCA)-treated wood products should not be used; mulch
where the CCA-content is unknown should be avoided
(see §2.5.5.1).
Table 2 shows the minimum required depths of loose-fill
material needed based on material type and fall height. The
depths shown assume the materials have been compressed
due to use and weathering and are properly maintained to
the given level.
2.4.2.3 Installing loose-fill over hard surface
CPSC staff strongly recommends against installing playgrounds
over hard surfaces, such as asphalt, concrete, or
hard packed earth, unless the installation adds the following
layers of protection. Immediately over the hard surface there
should be a 3- to 6-inch base layer of loose-fill (e.g., gravel
for drainage). The next layer should be a Geotextile cloth.
On top of that should be a loose-fill layer meeting the specifications
addressed in §2.4.2.2 and Table 2. Embedded in the
loose-fill layer should be impact attenuating mats under high
traffic areas, such as under swings, at slide exits, and other
places where displacement is likely. Figure 1 provides a visual
representation of this information. Older playgrounds that
still exist on hard surfacing should be modified to provide
appropriate surfacing.
Handbook for Playground Safety
4.3 Maintaining Loose-Fill Surfacing
Loose-fill surfacing materials require special maintenance.
High-use public playgrounds, such as child care centers and
schools, should be checked frequently to ensure surfacing
has not displaced significantly, particularly in areas of the
playground most subject to displacement (e.g., under swings
and slide exits). This can be facilitated by marking ideal
surfacing depths on equipment posts. Displaced loose-fill
surfacing should be raked back into proper place so that a
constant depth is maintained throughout the playground.
Impact attenuating mats placed in high traffic areas, such as
under swings and at slide exits, can significantly reduce Handbook for Playground Safety
17
Table 3. Routine inspection and
maintenance issues
Broken equipment such as loose bolts, missing
end caps, cracks, etc.
Broken glass & other trash
Cracks in plastics
Loose anchoring
Hazardous or dangerous debris
Insect damage
Problems with surfacing
Displaced loose-fill surfacing (see Section 4.3)
Holes, flakes, and/or buckling of unitary
surfacing.
User modifications (such as ropes tied to parts
or equipment rearranged)
Vandalism,
Worn, loose, damaged, or missing parts
Wood splitting,
Rusted or corroded metals,
Rot
displacement. They should be installed below or level with
surfacing so as not to be a tripping hazard.
The following are key points to look for during regular
checks of surfacing:
• Areas under swings and at slide exits. Activity in these
areas tends to displace surfacing quickly. Rake loose-fill
back into place.
• Pooling water on mulch surfacing. For example, wet
mulch compacts faster than dry, fluffy mulch. If puddles
are noticed regularly, consider addressing larger drainage
issues.
• Frozen surfacing. Most loose-fill surfacing that freezes
solid no longer functions as protective surfacing. Even if
the first few inches may be loose, the base layer may be
frozen and the impact attenuation of the surfacing may be
significantly reduced. It is recommended that children not
play on the equipment under these conditions.