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Dead Spots

In layman's terms, "dead spots" are locations on a sports floor where ball rebound is markedly less than on the majority of the rest of the surface. Many maple flooring systems exhibit vibrations and sound variations when a basketball is bounced at different locations. Often, areas where vibrations and sound variations are observed are mistakenly termed "dead spots." Provided the ball rebounds to a reasonably consistent height in comparison to other locations on the floor, areas where vibrations and sound variations are present do not typically qualify as true "dead spots."

Concerns about "dead spots" are most often expressed with floating subfloor configurations. Floating floors often exhibit sound and vibration variations due to the structure of the subfloor components. Ball rebound can be affected on all subfloor configurations due to seasonal changes in flooring moisture contents and resulting system expansion/contraction. It is not uncommon for a true "dead spot" to move or disappear as a flooring system adjusts to varying seasonal moisture conditions -- regardless of the subfloor system installed in the facility.

How do you confirm the presence of a true "dead spot" on your floor? For many years, MFMA and the entire sports flooring industry recognized the Wilson Sporting Goods ball bounce test as the standard for determining the presence of "dead spots" on a floor. With recent developments in performance engineering on flooring systems, the Wilson test method has been replaced as the recognized standard for ball rebound.

MFMA now recognizes the international D.I.N. #18032 Part 2 standards for a number of sports flooring performance issues. In most simple terms, the D.I.N. standards use a concrete floor as a base measurement for rebound performance, and compare rebound on all engineered surfaces as a percentage relative to results on concrete. Specialized equipment is used to time impact intervals of a ball dropped at multiple locations across an athletic surface, and calculations based on these impact figures result in a composite score for the floor. Variations from the composite figure are examined to determine the presence of any true "dead spots."

Most MFMA milling company members can provide laboratory-generated composite ball rebound figures for their flooring systems, and are available upon request for a fee to field test floors where "dead spots" are a concern.

If you have any additional questions, please contact MFMA's Technical Director at 847/480-9138.

Rev. 10/97

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