Critical fall height (CFH) is a vital safety standard for playground surfaces that was established by the American Society for Testing and Materials (ASTM). In essence, CFH is a measure of how well a surface absorbs impact, providing insight into how well the surface can protect against injury. It’s the height below which a life-threatening head injury should not occur, measured as the vertical distance between the playground surface and the highest play area. It’s important to understand playground surfaces’ CFH so you can take steps to reduce the risk of injuries.
How Is Critical Fall Height Measured?
Critical fall height for a playground is measured through impact testing. Testers drop a head-like form onto the playground surface and measure how fast and how hard the form hits the surface. The head-like form has a built-in device for measuring acceleration. These measurements determine how high someone could fall onto the surface without sustaining a serious, life-threatening head injury.
Where Is CFH Measured From?
The fall height, according to the ASTM, is the vertical distance between a play surface and the protective ground surface beneath it. Different types of playground equipment have CFH measured from different points, depending on how high a child could end up during normal play. Here are some common playground equipment types and where CFH measurements start from:
- Climbing equipment: On climbing equipment, testers measure CFH from the highest part of the climber intended for foot support.
- Upper body equipment: The CHF measurement begins at the highest part of any upper body equipment.
- Swingsets: The pivot point is the basis of measurement for a swingset’s CFH.
- Seesaws: On a seesaw, the CFH measurement is the maximum height the seat can reach.
- Spring rockers: The maximum height of the seat is also the measurement point for a spring rocker.
- Composite equipment: On composite equipment, the CFH point is the highest designated play surface.
It’s essential to understand where CFH height measurements begin, as these measurements do not account for improper use of equipment. For instance, a child climbing higher than the intended foot supports could exceed the measurement heights and sustain an injury as a result. Always make sure children are using play equipment as intended to avoid this issue.
Max Acceleration and Deceleration
Testers record two key measurements when the head-like form hits the surface, involving acceleration and absorption. The acceleration due to gravity is measured in terms of “G’s.” The highest “G” a surface can have is 200. Meanwhile, the head injury criteria (HIC) measures the time of deceleration. This measurement must be less than 1,000 to avoid serious head injuries. Specified fall heights include stricter standards for G’s and HICs.
Testers continue these CFH tests until they fail, meaning the G’s exceed 200 or the HIC exceeds 1,000. When you look for ASTM CFH results, you’ll see three reported measures, which are:
- The height at which the surface failed.
- The CFH, or the maximum height before failure.
- One foot under the CFH.
You’ll also see reports at three different temperatures, as temperature variation can cause discrepancies. The tested temperatures include 25 degrees Fahrenheit, 70 degrees Fahrenheit and 120 degrees Fahrenheit.
Critical Fall Height vs. Specified Fall Height
A new ASTM standard method allows for laboratory testing at specified test heights (STHs)- ASTM F3351. This involves different heights than the standard CFH using the same procedures. It improves playground safety standards, as it allows consumers to require better performance than the established 200 G’s and 1000 HIC.
Rather than having to rely on the standardized limits above, you can request safer standards. For instance, you could require 120 G’s and 700 HIC at 8 feet at initial installation then request the surfacing company to field test the new surface before you open your playground for use. The lower Gmax and HIC values give your surfacing functional longevity which means it will perform longer into the life of the playground. This is especially true for unitary surfaces, such as poured rubber, tile and turf systems. You can also request a surface guaranteed not to exceed a certain level of G’s and HIC for a determined number of years. Lowering the acceptable HIC and G levels can help reduce the risk of serious injury.
What Does It Mean for Playground Surfacing and Equipment?
The critical fall height for playground equipment is important to consider. Playground falls are a significant cause of injury for children. According to the Centers for Disease Control and Prevention (CDC), over 200,000 children sustain playground-related injuries each year in the United States, with many instances resulting in traumatic brain injuries. Safety standards such as ASTM F1292-CFH & ASTM F3351-SFH help save lives and keep kids out of the hospital.
Playground surfaces and equipment must meet ASTM standards for CFH to reduce the risk of serious injury, including traumatic brain injury. Tightening acceptable standards with lower specified fall heights can help keep children safer. Testing is also necessary after installation to make sure all standards are met.
Choose Critical Fall Height Safety Surfacing
When choosing playground surfacing, opt for a surface with enough depth to absorb impact and shock. Verify that the surface meets ASTM F1292 for CFH standards or stricter specified height standards- ASTM F3351. For maximum play safety, look for a surface with a G and HIC rating of at least 20% below the failing criteria specified in the standards. Make sure your playground equipment height does not exceed the surface CFH rating, most often 8 feet.
Best Surface Options
If you’re looking for a safe playground surface, consider using one or more of the following options:
- TuffMat Zero-Fill mats: A TuffMat Zero-Fill mat can help cushion falls around swingsets, slides, spinners and other high-movement areas. These mats have a certified impact rating of 8 feet. They come in a variety of sizes to accommodate different play space needs. They’re also accessible and compliant with the Americans with Disabilities Act (ADA). They require no fill under or above the mat, which makes them easy to install and more importantly maintain.
- RecBase poured rubber: Another good option is a RecBase poured rubber surface, with a fall safety rating 20% better than ASTM requirements. It comes in a variety of mixed color choices for a fun, playground-friendly feel. It allows for fast, consistent installation. Each installation includes fall safety on-site testing.
- WoodCarpet engineered wood fiber: Made from virgin, clean lumber-grade chips, a WoodCarpet surface has an impact rating of 8 to 12 feet depending on its depth. It’s ideal for accommodating kids’ trips and spills, absorbing their impact to reduce the risk of serious injuries. It also offers good water drainage and easy maintenance when combined with Zeager-recommended drainage and wear mats.
Request a Quote for Zeager Bros., Inc. Surfaces
Understanding ASTM critical fall height ratings can help you make safer choices for your playground surfaces and equipment. A surface that meets or exceeds CFH standards will lower the risk of serious injury and help keep kids safer. If you’re looking for a safe, ASTM-compliant playground surface, consider Zeager surfaces.
At Zeager, we’re a leading manufacturer of landscape and recreation surfaces, including impact-absorbent playground surfaces. We create both natural and synthetic ground options, offering accessibility and easy maintenance. Learn more about our playground surface options and request a free quote today.