Grain Power

When choosing a wood floor for your basketball court, think hard about how you want it to look -- and how you want it to play.

Wood floorWood floorWood athletic flooring is used in a variety of different sports, including basketball, volleyball, racquetball, floor exercise, ballet and ballroom dancing, to name just a few. Installation of a wood floor in most of these applications is a fairly straightforward proposition. Basketball, however, is a whole different ballgame.

Floors for basketball must be forgiving to athletes' joints and resilient enough to allow for optimum ball bounce; at he same time, they must be solidly built to allow 10 athletes to run and jump without displacing the players around them. They must also be specified for permanent installation over many different types of subfloors, or specified as movable -- while still maintaining stringent play characteristics wherever they're installed. It is for these and other reasons that basketball floors are the most complicated and misunderstood of all wood floor applications.

The Ground Floor
A wood floor installation starts beneath the surface, with close attention paid to substrate tolerances. Designers should always specify the tolerable floor flatness ratio that will be accepted for either a permanent or portable flooring system. Permanent floors can absorb more irregularities and unevenness than portable floors, since correctable measures such as shimming can be taken during the installation process.

In either application, though, the flatness of the concrete slab is essential. An uneven concrete floor can cause the floor to assemble incorrectly, allow large cracks to develop, cause serious damage to the floor's locking system, or damage the surface layer of the maple and finish. An uneven concrete floor can also cause irregular action of the game ball or even cause injury to participants.

The type of floor chosen will often require alterations to the subfloor. For example, permanent floors require the concrete slab to be recessed, usually around three inches, so that the top of the playing surface is even with the surrounding floor slab. The various categories of wood sports floors fall into three simple types. Portable floors sit about three inches above the floor surface and are designated as "floating" systems. Permanent floors are fixed systems, meaning they have some attachment to the concrete, as either a "sleeper" system or a "fixed/floating" system.

The third type, an "anchored resilient" system, is mechanically attached to the concrete substrate, but has a combination of components with varying degrees of additional resiliency within the subfloor system. These components range from additional wood substrate, channel systems, pads and other neoprene-type cushions, and special anchors that allow for movement and resiliency in the system.

A traditional sleeper floor consists of (usually) 1- to 1 1/2-inch-thick solid wood members or engineered plywood laminations that rest directly on the concrete floor. The sleepers run perpendicular to the finished surface maple planks and are spaced anywhere from 4 to 12 inches apart.

Cushion construction utilizes neoprene, rubber or similar-material pads coming into direct contact with the floor-bearing surface. The pads are attached to a plywood substrate or channel support system that the maple planks rest on. The pads are typically 1/2- to 1-inch high and are spaced 4 to 12 inches on center in each direction.

Channel construction uses steel or another composite, heavy-gauge material to support the maple deck and plywood substrate. The channels are attached or rest directly on the concrete floor, run perpendicular to the finished planks and are spaced typically like a traditional wood sleeper floor. The channel allows the wood floor assembly to move up and down, offering flexibility and the all-important "rebound" and "flexure" characteristics that are sought in high-end performance wood floors.

"Fixed/floating" systems offer the most advantageous aspects of these different wood floor construction types by combining either the sleeper style or the channel style with the pad or cushion concept. These floors, which manufacturers have available in a range of assemblies, combine one of the key characteristics of a successful floor, resiliency, with the flexibility given by sleepers and channels.

Plank Verse
Maple has been the species of choice for wood basketball floors since the late 1800s based on its characteristics of performance. Properly grown, harvested and milled maple offers a blend of a durable yet resilient surface, low cross-grain shrinkage, and acceptable performance values in surface rebound, deflection and shock absorption. (Although this article addresses only solid wood maple flooring systems, it should be noted that engineered products, which utilize a multi-ply construction with a solid-wood face, are another popular option, particularly in Europe.) Solid wood floors come in three distinct grades of finished maple: first (competition grade), second (standard grade), and third (multipurpose grade). The grade of the wood is an appearance factor only. The structural or dimensional properties of the planks are not different or sacrificed from one grade to another.

First grade has the appearance of almost defect-free wood, meaning no large color deviations, blemishes, knots or other discolorations or surface defects in the grainy appearance of the planks. The few surface defects in second-grade floors may include small knots and blemishes and a small deviation in the overall tint range of the individual planks. Third grade accepts all structurally stable planks that have surface defects, knots and blemishes, as well as a wide variation in tint from plank to plank.

National Basketball Association guidelines prefer that all of the league's wood floors be first grade. Colleges sometimes prefer second grade over first grade because the variation in color actually makes the floor look more vibrant and less "whitewashed." Third-grade floors are normally reserved for practice gyms or very small college and high school gyms. Their extreme variation in color, due to the acceptance of darker heartwood in the grade, does not read well on television broadcasts.

Maple flooring comes in three basic plank configurations: random-length strip (the most common), finger-jointed strip and parquet. Random-length strip means individual pieces of flooring, typically 1 1/2 or 2 1/4 inches wide, with lengths between 8 and 9 feet. Finger-jointed strip contains a number of random-length strip segments joined together at the manufacturing plant to form a board of consistent length (the standard is 7 feet). In both cases, the wood (usually 25/32-inch thick, but also available in 33/32-inch material) is installed like a horizontal brick wall, with each piece being overlapped with adjacent pieces and fastened into the subfloor with cleats, staples or steel clips, depending on the subfloor chosen for the project.

Parquet flooring is manufactured in square and rectangular panels in a variety of dimensions. Individual picket widths range from 7/8 to 1 1/8 inch, and picket lengths range from 5 1/2 to 12 inches. The minimum thickness of parquet flooring is 5/16 inch. Individual pickets, assembled into panels, are either joined together by wire, mesh or tape on the back of the panel, or a paper face on the panel's top surface.

Portable floors are assembled in 4-by-8-foot panel sections. Each manufacturer of portable floors has a different method of locking the panels together, but all are based on a principle of laying the panels out in a specified order and locking the adjoining panels together as they are positioned from side to side. Portable floors can be assembled starting at one corner (the starting panel is usually designated the "A-1" panel) or from the center of the court. The position of the A-1 panel is determined during the initial installation and marked permanently on the concrete floor so that subsequent installations are identical.

Portable floors typically require that a small additional extension be provided along the baseline to support the base unit on most portable basketball goals. Extensions should be ordered in conjunction with the purchase of the main wood floor to ensure that the depth, construction and finish of the extension matches the main wood flooring assembly. The extension should be a foot wider than the base of the portable goal on each side and at least 24 inches longer than the base unit's length.

For basketball-only facilities that have no ice surface underneath, careful planning should be practiced to ensure that the power and signal source to the portable basketball goal can be accessed in the slab and is not covered up by the goal-base extension. The same is the case with all electrical power and data/communication lines that are cast into the concrete floor. These include power lines to the scorer's table; data and control lines from the scorer's table to the scoreboard, shot clocks and horns; and power, phone and data/communication lines for floor-level press tables. A portable floor is cored at the location of junction boxes and covered at the finished floor level with a brass or chrome lift-off plate. Additional floor sleeves, such as those used to hold volleyball standards and tennis posts, must also be coordinated between the portable floor and their location in the concrete subfloor.

Good Wood
Floor characteristics and properties are defined generally by two widely accepted testing methods for determining the performance of wood floors; the STEM method and DIN method. STEM testing exposes strengths and weaknesses of sports flooring systems as a whole. DIN testing allows purchasers to compare systems on an industry-accepted testing scale. DIN 18032-II is considered the benchmark certification process by leading wood flooring manufacturers and is the most recognizable testing procedure among NBA and collegiate clientele. While DIN is certainly the most recognizable testing standard, it is doubtless also the most misunderstood.

The basic parameters of DIN testing are ball deflection, shock absorption, vertical deflection and area deflection. Ball deflection measures the ball's response off the sports floor system as compared to the ball's response off concrete. Shock absorption measures the floor system's ability to absorb impact forces normally absorbed by the athlete by landing on a hard surface, such as concrete. Vertical deflection measures the floor system's downward movement during the impact of an athlete landing on the surface. Area deflection measures the floor system's ability to contain the deflected area under an athlete's impact, measured within 20 inches of the impact.

STEM testing measures environmental stability, system loading, resilient life and resilient load. Environmental stability measures the sports floor system's ability to remain unaffected by significant swings in environmental conditions such as humidity. System loading indicates the ability to maintain integrity under excessive loads, such as bleachers or vehicles. Resilient life measures the pads' ability to provide unchanged performance after repeated active loads. Resilient load measures the pads' ability to provide unchanged performance after carrying excessive loads.

DIN tests are driven by athletic performance, while STEM tests are driven by engineering performance. Combined, these two tests measure a wood floor system's rank when compared to industry standards and to other available wood floor systems. Testing of surfaces designed for sports usage is performed by the United States Sports Surfacing Laboratory Inc. (USSL), an independent testing company.

Along with consideration of performance characteristics, wood-floor specifiers may wish to select a "green" product, especially if the building owner is trying to achieve LEEDTM certification. Specifiers should look for manufacturers with membership in the Maple Flooring Manufacturers Association and who utilize SmartWoodc, a certified forestry program designed to maximize the positive effects of commercial forestry on local communities and to reduce the long-term environmental impact.

In lieu of traditional 33/32-inch thick planks, specifiers should consider using 25/32-inch maple plank products, since the thinner profile means less wood is used.

Understanding the technical aspects that make a wood athletic floor system appear and perform properly is essential to the success of the floor's function. All parties involved in the selection and installation of a wood athletic floor are encouraged to research and understand the various components of this unique athletic surface system. Advice from an experienced design professional can help clients sort through the multitude of different floor systems and select the proper wood floor that best meets the needs of the facility and the athletes who perform on it.

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