Hardwood Basketball Court Damage Claims Expert Article

Hardwood gymnasium floor systems (basketball courts) have evolved substantially from the traditional tar, wood nailer course (sleepers), and finished floor material. Whether the court is in a school gymnasium built decades ago, a professional ballet’s sprung floor, or an NBA arena’s high-performance portable court, all are susceptible to damage from improper maintenance or exposure to moisture.

In this article, architect and construction expert Mark Sullivan will explore some of the basics of hardwood athletic flooring systems and potential causes of defects and damage such as cupping, crowning, and buckling.

Wood Court Basics

A court’s finished playing surface is typically made of Maple with additional layers ranging from wood anchoring slats to plywood and resilient shock absorbing layers. The layer thicknesses and material types can vary to suit generalized athletic use for a school gym (basketball, volleyball, wrestling) or they can be specialized for a single use such as dance. Traditional and high-performance hardwood floor systems can vary from 1 ½” to as much as 3 ½” in overall height depending on which system is used.  

Portable hardwood floor systems used in NCAA tournaments and by NBA teams are typically installed onto an existing surface for a short period of time. When not in use, they are broken down and stored in 4’x8’ sections. Their system height can be accommodated with perimeter ramped transitions above the existing surface.

Permanent court floor installations typically require a floor slab depression for the playing surface to be flush with adjacent flooring. During installation, the support layers of a court run perpendicular to the direction of the boards at the playing surface.  This cross-stacking of material creates void spaces to allow the system to flex, expand, contract, and provide a path for air movement.   

Wood is naturally porous and can absorb moisture in both liquid and vapor form. It will expand or contract when subjected to variations in temperature and humidity. Court expansion and contraction is accommodated at the perimeter of the court by leaving a gap of roughly 1 ½” between the edge of court and the edge of slab depression. The expansion gap is bridged with an ‘L’ shaped vented base that conceals floor movement and allows humid air to escape.

Sources of Damage to Athletic Courts

Court damage can range from minor floor irregularities such as cupping or crowning of boards and damage to floor finishes, to major failure (burst pipe or flooding) where the floor system detaches from the substrate and buckles above level. Depending on the severity of damage, repairs can range from sanding and refinishing to partial or complete removal and replacement of the system. 

With any hardwood flooring system, the tolerance for variations in level is low. Slopes or irregularities of the sub-floor upon which they are installed can create performance issues for the floor and for the athletes, dancers, and other users. 

Court system damage is often identified as one of the following:

• Cupping
• Crowning
• Buckling 

Cupping of the wood surface can be from excessive moisture exposure. The width of the wood board’s bottom surface can become longer than the top surface and this differential creates a “cupping” effect of each board, forming a series of small peaks along their length. The bottom edges of the board are also raised but are not visible.

Crowning is the opposite of cupping and can occur after sanding a previously cupped floor that has not been adequately acclimated. When the peaks are sanded flat prematurely, the bottom remains wider with raised edges above the sub-floor. As the sanded floor continues to acclimate, the bottom raised edges will lay down and result in a crowned condition.

Buckling is the most extreme form of court system damage that can range from floor undulations of a few inches up to several feet above the sub-floor. A burst pipe or stormwater flooding can fill a permanent court system’s floor depression. If the trapped water is not immediately removed or drying of the floor is delayed, excessive expansion will cause the court system to push against the perimeter.

Once the 1 ½” expansion gap is gone, the floor system has nowhere to go but up, separates from the sub-floor and large undulations are formed. 

Moisture Sources that can Damage Wood Courts

Improper Humidity and/or Temperature Control

Multi-purpose arenas host a variety of events and require the flexibility of quick installation and removal of a sport floor throughout the year. Portable floor systems made of 4’x8’ preassembled and interlocking panel sections are intended to fit this need. 

Manufacturers typically provide instructions and recommendations for how the portable panels shall be stored, stacked, and the environment in which they shall be kept. If those instructions and recommendations are ignored, the floor system can fail. 

A potential for permanent court system failure is the energy conservation practice of raising the air temperature or even shutting down HVAC systems entirely for extended periods of time to lower utility costs. Depending on the climate, this practice can result in swelling from excess humidity, or in arid climates, shrinkage can create visible gaps between boards.

Condensation or Localized Conditions Caused by HVAC Systems

A facility’s mechanical HVAC system is a critical factor in the life and playability of a wood sports floor system. 

Improperly insulated overhead ductwork, internal/horizontal storm drain piping or mechanical piping above a wood sport floor can create condensation and cause localized damage of finishes or wood boards. This can be the result of improper design, improper installation during construction or improper HVAC operational practices. 

Inadequate Waterproofing

When the finished floor of a court is lower than exterior grade, geotechnical considerations such as ground water elevation level must be evaluated during the design phase. Ground water can become a source of direct water infiltration below a floor system due to hydrostatic pressure beneath the slab. 

Lack of waterproofing, improper installation of waterproofing or lack of an under-slab drainage system are all factors that can contribute to moisture infiltration. These sources of moisture are not readily identifiable and can cause damage to a wood sport floor.

Damaged Wood Court Expert Investigations

The investigation of a damaged wood court will typically require a site inspection and the review of available information such as:

• Specifications and submittals
• Construction Field Documentation
• Geotechnical data
• Foundation and slab details
• Mechanical and plumbing documents
• Waterproofing and vapor barrier specifications
• Product data submittals

Causation, damages, and design/construction standard of care in these cases is often best addressed by an architect with experience in sports facilities.

For more information, submit an inquiry or call 800.813.6736.

Featured Expert

Mark T. Sullivan, AIA, NCARB, CDT

Architecture, Construction & Premises Safety Expert

Mark Sullivan is a Texas-based registered architect and construction administration professional with more than 25 years of practical experience. His architectural career began with single-family… read more.