(Warning this is a LONG post.) An earlier post (104) introduced the Area Deflection property of sports surfaces. This article delves deeper into that property and explores the requirements of some international standards, governing bodies, and trade associations. This paper focuses on area elastic indoor courts. Mixed and combination elastic courts will be covered in another document. Point elastic surfaces such as synthetic courts and running tracks to not produce area deflections.
Before I present the requirements I want to address this topic from a somewhat philosophical point. EN 14904, and ASTM F2772 (as of 2017) do not even consider area deflection. The DIN 18032-2 (1991) standard only considered the average value of area indentation. Within DIN-1991, Area Deflection was weighted equally with force reduction, vertical deformation and ball rebound. By that I mean that a sport surface had exactly ONE way to fail each property.
Since the passing of the newer DIN 18032-2 (2001) Pre-Standard many standards and groups have adopted that standard’s new format. The DIN-2001, and the FIBA rules for sports surface performance have adopted a policy that establishes allowable limits for area deflection in 4 directions around a test point, while retaining limits on the average value (surfaces are 5 times more likely to fail this area deflection in DIN-2001 than in DIN-1991). While the MFMA took a slightly different route, they place maximum allowable levels in each of the 4 directions but not the overall average (surfaces are 4 times more likely to fail this area deflection using MFMA PUR than in DIN-1991). Each of these standards, has, in essence, adopted the philosophy (knowingly or accidentally) that Area Deflection is far and away the most important property of a sports surface. Why do I say that? Because there are many more ways for a sport surface to fail area deflection than any other property. Here are some examples:
- Force Reduction – Two ways to fail (average and uniformity)
- Ball Rebound – Two ways to fail (average and uniformity)
- Vertical Deformation – Two ways to fail (average and uniformity)
- Area Deflection – DIN-2001 = 5 ways to fail (individual directions, and average value) / MFMA-PUR & FIBA= 4 ways to fail (individual direction). As a note the FIBA rules are significantly easier to achieve than the DIN 2001 or MFMA-PUR standards.
The new standards that use 4 direction tests and analysis for area deflection have created a situation where area deflection is as important as force reduction and ball rebound. There are (2) ways for a floor to fail force reduction and (2) ways for a floor to fail ball rebound, while there are 4 or 5 ways for it to fail area deflection under these new standards.
Architects and owners that place requirements for Area Deflection performance in their specifications should also be aware of how sensitive it is. A floor with a 2.3 mm deflection during impact passes with an Area Deformation level of 14% but fails with an level of 16%. That represents an difference in the measured deflections of 0.046 mm or 0.0018″ or 1/550 of an inch. A floor with a relatively large failure (20% instead of 15%) may represent an increase in deflections of only 0.12 mm, or 0.0045″ or 1/220th of an inch. ASET Services, along with labs around the world, routinely fail products due to 0.001″ too much deflection, and manufacturers struggle with designs to try to remove that 0.001″. Each owner and architect must decide how important this property is. They also need to consider the difficulty for actual installations to deliver specified performance levels given the uncertainty of actual job site conditions and the extremely sensitive nature of this property.
Now, I believe that I have supplied the proper context to consider the requirements of individual standards. Presenting the requirements for each standard is a daunting task given the limitations of the formatting available on LinkedIn. With that in mind I put together another summary table. Click here to download the table.
Click here to download the table.