There are basically two categories of playground surfacing; Loose fill & Unitary surfaces. Loose fill surfaces such as EWF (engineered wood fiber), gravel, wood chips & sand come from natural elements (except in the case of loose fill rubber) and are just what the term means “loose”. In other words, there are no binders or other chemicals holding them in place and they are generally installed in thicknesses anywhere from 6” to 12” thick depending on the amount of fall height needed on a particular playground.
Unitary surfaces are bound elements formed into tiles or rolled products such as turf. These surfaces include rubber tiles, poured in place rubber and artificial turf or carpeting products. Their makeup can come from recycled tires, virgin rubber, nylon, polyethylene among other synthetic components.
What are their benefits? Loose fill surfaces are generally less expensive, do not require professional installation, drain well and on average give greater fall height protection than unitary surfaces. The drawback is more maintenance is needed since loose surfaces are just that – loose! So they tend to scatter in high use areas and need replenished, raked, leveled and compacted periodically in order to keep them safe and accessible which increases maintenance costs. There are products to help with scattered material in high use areas. These are referred to as wear mats and come in all sorts of sizes depending on the area that the mats need to protect.
These are not an end all to the maintenance needed but can really reduce the amount of time spent filling in these areas on a routine basis and will help keep the area safe between maintenance intervals. Some manufacturers have their mats certified to certain fall heights. Ask for test results so you aren’t actually reducing the safety of these areas by installing mats. The mats are also not intended to be installed and then left alone. The maintenance worker should still inspect these periodically to make sure the transition from the mat to the surrounding surfacing is relatively smooth. To within a half inch which is required by ADA guidelines.
I also recommend placing them in not only obvious spots like slide exits and under swings but look around at your playground and you will notice that placing them at ground level components like play panels and transition platforms will help those with disabilities enjoy these areas without the risk of uneven surfaces.
Unitary surfaces do not require a lot of maintenance so they are desirable for those that have high budgets and limited help to maintain their playgrounds and usually have longer warranties on materials except in areas that are considered high use such as swings and slide exits. Ask for warranty details before purchasing. They also come in an array of colors so you can really create some cool themes with some of these types of surfaces.
The downsides to these types of surfaces is that they have more upfront material & installation costs, require professional installation, can be extremely hot during summer months and generally do not have the same impact resiliency as loose fill products. Always ask to see test results or certification papers to be sure you are getting a surface that will protect you and the children using the play area. I would also suggest getting your unitary surface impact tested periodically, every 3 years or so. The reason? Because unlike loose fill surfaces where you can measure the thickness of your surfacing to see how much you need to top off periodically to keep it at safe levels, you can’t see what’s going on down below the top wear layer of a unitary surface. The surface may look good on the top but if it has begun to decay or is getting harder beneath the wear layer it may not be safe and the only way to determine that is to perform a drop test. There are many playground consulting companies that offer this.
Some experts have also suggested that more long bone fractures like wrist and ankle injuries can occur on a unitary product versus a loose product because loose surfaces will move as impact occurs rather than staying put like unitary surfaces will. Formal studies need to be done to confirm this.
What are their maintenance requirements? See above.
What factors should an owner consider as they choose which type of surface to specify or install?
Let’s be honest here, there is no perfect surface! A surface should be the total package – Safe, accessible, available and affordable. So let’s take them one at a time;
Safe: ask the manufacturer for recent impact test results per ASTMF1292 (within a few years) and if they have any test results from an actual installation out in the field. Are the numbers on the edge of failing or is there plenty of room in case of harsh weather which could affect the resiliency of the surface. If using EWF ask for test results for ASTM F2075 or for Loose fill rubber ask for ASTM F3012 which checks for sieve analysis, tramp metals like nails and staples and hazardous metals like Lead, Mercury and Arsenic.
Accessible; Get a recent ASTM F1951 test result showing it passes for accessibility but also see if the vendor has any installation instructions or maintenance recommendations to keep their surface accessible. If you can maintain it, you can rest assured you’ll meet ADA guidelines if you install it correctly per the manufacturer’s instructions.
Availability? No, I don’t mean whether the surface is available. Any vendor can sell you something. I mean, will you have the support available when you need it, will the vendor be there when you need to know how to get the most out of your purchase or when there is a warranty issue. Most playground owners don’t have the time to chase down a vendor and then get the run around when it comes to questions and answers to the product they purchased. They want their vendor or manufacture available when something pops up.
Consider your budget; It’s easy to say “let’s put a unitary surface in so we can lower our maintenance costs” but unitary surfaces range from $10 to $20 a square foot while a loose fill surface such as engineered wood fiber is only about $1.50 to $2.50 a square foot. For some large school districts and municipalities that have literally hundreds of playgrounds, it’s easier to top-off and maintain the playground on a weekly or monthly basis then forking out a large sum of money and draining their budget. But if you don’t have the personnel to maintain a loose fill surface, then maybe a unitary surface is for you. There is still some maintenance to be done like keeping it clean or patching some rough spots in high use areas but overall they are definitely less needy.
Are There Certain Surfaces More Appropriate For Different Climates?
Above I mentioned that you should ask for impact test results from your manufacturer. These test results should be per ASTM F1292 test method. This test method simulates the impact of a child’s head with the surface. The test method quantifies impact in terms of “G-max” referred to as “Peak Gmax” and Head Injury Criteria (HIC) scores. The test is performed in 3 temperatures; Ambient (70F or so), Freezing (25F) and in heat (120F). This helps the buyer determine how the surfacing is going to perform in extreme temps. But remember, these tests are done in a lab setting so consider other factors like drainage when you install your surface.
You wouldn’t think drainage would lend to a surfaces safety but it does! Imagine a surface that doesn’t drain well in a cold climate where temperatures fluctuate, causing snow to melt and then re-freeze overnight. Any amount of frozen moisture that is within the surface makes the surface less resilient and unable to provide good impact attenuation so eliminating water from the surface will minimize this and help the surface to last longer too. It really goes back to making sure the owner/ operator of the playground has the surface installed properly and that the testing they receive simulates in the lab what the actually surfacing is going to be out in the field. When you look at the test results, look at the description of the surface to make sure it represents what you are purchasing from the vendor.
And as always, we recommend limited play in harsh temperatures no matter where you live. Better to be safe than sorry.
Are There Any Trends in the Surfacing Manufacturing or Installing Business…New Materials, Etc.?
The trend that I see as of late is going back to nature. This includes play equipment that replicates natural elements like boulders and climbing walls that look like the real thing to actual play settings in the woods that include rocks, stumps & logs to play on. Kids like to use their imaginations so there’s nothing like making a fort out of limbs and branches. EWF seems to be the surfacing of choice in these areas since it’s still a natural product but comes with testing and certifications to back up the safety element needed in all play areas.