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For Poured-In-Place Rubber and Synthetic Grass Safety Surfacing.
As with any project, budget rules. The cost of safety surfacing (both rubber and grass) can fluctuate greatly depending on the color scheme, thickness of the rubber, amount of sq/ft and design work. For rubber, the least expensive option would be to blend black with one of the standard colors. Black EPDM is much less expensive than colored EPDM. Another cost saving is to design in “less” sq/ft of rubber. Keep in mind when doing this that another material will need to be used to fill in the rest of the area which can lead to messy and expensive maintenance issues. Utilizing Rubber in the fall zone areas and the rest of the area with synthetic grass is a good alternative. This gives the attenuation needed in the fall zones while keeping the rest of the area ADA accessible and maintenance free. This also looks very attractive (see our Photo Gallery for examples).
Designs in rubber surfacing are very aesthetically pleasing but they come at a cost. For every color or design change a seam is required to transition from one color/design to another. Seams can cause a challenge if not installed correctly. They can split apart causing an ugly “rip” or “tear” in the rubber. To avoid this, make sure the installer utilizes a step seam technique. This is where the rubber is stepped down from ½" to ¼” and then trowelled out another 6” from the edge. This creates a tongue and groove effect and the seam holds for a much longer period of time (See example on our specs page). Priming the seam connections with additional urethane is also recommended.
Adding color to a pad can really enhance the look of the surfacing. Make sure that if the color added is anything other than green, tan, red or blue that an aliphatic urethane is utilized. Aliphatic urethane is different from traditional urethane in that is does not amber or fad the rubber and creates a much stronger bond between the rubber particles. Aliphatic urethane makes the rubber color fast and gives it that “just installed” look for years to come. Aliphatic is the best urethane on the market but also comes with a price tag to match.
Most poured in place rubber surfacing has a weakness. It’s the border where the rubber meets the sidewalk (or other connecting surface). After a couple of years this connection will separate leaving a “gap” between the rubber and the curbing. This happens because rubber expands and extracts with temperature changes. After awhile, the rubber will contract to it’s fullest and the result is this gap that can cause trip hazards and pinching. To avoid this issue, the connecting surface should be stepped (inset) ½” deep and 3” wide (see an example on our specs page).
Don’t forget the sq/ft of the turn downs when designing rubber surfaces. Turn downs are utilized when the rubber does not meet a connecting surface. Typically a turn down is used when the fall zone or access pad is rubber surfacing but the rest of the play area is sand or wood chips. The rubber turns down at a 45 degree angle hiding the edge of the rubber well below the level of the loose fill material. As long as the loose fill material is kept at the appropriate level, this will keep children from finding the edge and doing damage. Most turn downs are 1.5’ long adding this sq/ft to the total of the surface area.
Synthetic Grass as a Wear Course:
Utilizing Synthetic grass as a wear course layer has some advantages. Typically, a grass surface has a longer warranty, the color does not fade and repairs can be made without any sign of the original damage (due to the grass blades hiding the seems). When choosing a synthetic grass safety surface for your playground area, you will want to ask a couple of questions. 1) Is the grass system ASTM 1292 compliant? Is the grass system IPEMA Certified. Will the attenuation of the grass system lessen over time due to lose infill within the blades? What is the face weight of the synthetic grass?
Synthetic Grass Face Weight:
Face weight has a lot to do with the durability of the grass safety system. The face weight refers to the weight of the yarn used to make the individual blades of grass. The heavier the face weight, the denser the grass blades which leads to a more durable product and a longer life cycle. Typically the face weight and the stitch count will tell you how durable a particular grass product is. The stitch count refers to the amount of stitches in the face of the grass. More stitches means better quality.
Synthetic Grass Cushion:
The cushion layer of your synthetic grass safety surfacing is the most critical component of the install. If the cushion layer is loose fill it will move around and wash out during a storm. You wouldn't lay carpet on top of wood chips or sand and call it a safety surface so grass should not be installed this way either. In addition to the safety cushion, the infill that goes onto the surface serves 2 purposes. The first is to weigh the grass down so it does not move around on you. The second (and erroneous) purpose is to add cushion to the system. The challenge with this is that the loose granule infill move about and disburses leaving you with a non-compliant attenuating surface. An acrylic infill will weigh the surface down; cool the temperature by 10-15 degrees while not interfering with the ASTM standards. The best way is to install the cushion with the capability to withstand the Fall Height and Gmax criteria even if the grass is disturbed. The only safe way to do this is to install a system that does not incorporate loose fill and has no panel edges that will rise in the middle giving the grass a “bumpy” appearance.
Utilizing Grass for Access Ramps:
This should never be done. The reason is that the surrounding loose fill (sand or wood chips) will overlap the grass and fill in the blades. When this happens you lose all attenuation and find yourself with a non-compliant safety surface. The only material that should be used for access ramps is poured-in-place rubber.
Don’t forget the sub base. Poured in place rubber requires a minimum of 4” compacted ABC aggregate or at least 3” of concrete or asphalt. Grass requires a minimum of 2” compacted aggregate. These are minimums. Mot playground pits are deeper so they will either require a backfill material (such as compacted dirt) or the sub base will need to fill the entire depth of the pit (minus the thickness of the safety surfacing).