The Crucial Finishing Touch
By Tom Mitchell
Multi-use flooring options for a project at a church, school activity center or gym include wood, carpet, tile and synthetic surfaces. The key selection criterion is the variety of activities the space is likely to host. If the primary focus is athletics and the budget is a bit more robust, a maple gym floor may be the best match. Many wood systems are available, from free-floating to more costly and complex anchored floors.
For more varied usage, with activities including street shoes, chairs and tables, other surfaces may be more practical than wood. Carpeting, popular 20 to 30 years ago, is declining in preference with increased emphasis on recreation in these areas, and the poor slide characteristics and hygiene issues related to rug burns. Also if food and beverages are present, cleaning and maintenance become a greater consideration.
Given the concerns and limitations associated with wood and carpet, many synthetic choices emerged in the '70s and '80s. Interlocking tiles entered the market as an economical way to spruce up a room without worries about environmental controls and extensive slab cleaning and prep, particularly in a retrofit scenario to replace an existing surface. Interlocking tile can be placed over slabs with higher moisture levels than with wood or other synthetic options. The industry norm for acceptable moisture levels in concrete below flooring is about 3 percent to 5 percent—a difficult benchmark to achieve in some conditions, and often necessitating a chemical vapor barrier to block moisture transmission from beneath the slab.
Other floor options include prefabricated rolled/sheet goods, and poured-in-place urethanes. Prefab floors fall into two main types: rubber and PVC. Rolled products are "uniform" in nature, relatively easy to install and available in many colors and patterns. Vulcanized rubber floors can offer a variety of performance layers to enhance shock absorption and longevity. Their PVC counterparts share many similarities but have a plasticizer component that can leech out over time and cause the floor to shrink and harden. A further drawback to prefab floors is their seams; more than an aesthetic concern, seams present maintenance and safety issues. When these surfaces need to be refurbished, they must be removed and disposed of, the slab cleaned and prepped for a new, full-thickness prefab replacement.
Poured-in-place urethane floors were introduced in the '70s. Initially made in prefab sheets, "in situ" or on-site fabrication soon followed, which is both this system's biggest advantage and largest potential drawback. For almost 20 years, self-leveling urethanes were poured directly over the concrete substrate; researchers soon addressed adhesion issues and developments to enhance elasticity and shock absorption. Athletes want optimum "give" and slide for comfort and safety, while those who care for the surfaces want a product that is impervious to damage. In the past 15 years, these concerns have led to pad-and-pour systems.
Europe has been at the forefront of synthetic sports floor technology, as they lack the maple resources enjoyed in the United States and must satisfy a spectrum of applications often best met synthetically. The Dutch were the first to employ a recycled rubber underlayment to pour self-leveling urethanes over. The cushioning aspect of this underlayment enabled urethane to be redesigned for greater durability. This also resonated with increasingly prevalent "green" initiatives; a typical-size family life center floor would incorporate almost 500 tires that otherwise would be consigned to a landfill.
After gluing down the rubber underlayment (thickness depends upon desired cushioning and budget), the mat is sealed, followed typically by two self-leveling pours of urethane. A pigmented urethane coating is then roller-applied. Game lines and artwork complete the installation. In the past, clear maintenance coats over the finished surface led to worries about slipperiness or the protective coating cracking/crazing because its stretch characteristics differed from the floors beneath. Again, Dutch formulators addressed these points with a better-protected, easier-to-clean floor with longer warranty.
Seamless construction remains one of the biggest reasons for the popularity of poured urethane along with its ability to be refurbished in 12 to 15 years with an over-pour "facelift" at half the cost of the original installation. While most urethane wear coatings are solvent-based, with troublesome fume issues and VOCs (volatile organic compounds), new innovations with water-borne coatings make these systems dramatically "greener."
A controlled environment is necessary for wood floors, and their maintenance is more involved; to keep a maple floor in top condition, budget around $.30 per square foot annually to screen and recoat, and roughly $1.50 per square foot every 10 years to sand and refinish. A properly-cared-for wood floor should last 60 years with annual rescreening and periodic sanding and refinishing. Synthetics usually need some refurbishing in 12 to 15 years, when they will require either total replacement or an over-pour. A walk-behind scrubber is a good investment, making the routine cleaning process go more smoothly and, with other attachments, can be used in other facility areas. A medium spectrum pad or brush with a good neutral cleaner should help maintain a floor in both appearance and playability.
Regarding site conditions required for proper installation of a new surface:
- Concrete should be free of any curing compounds or sealers which could preclude proper adhesion. It should be at least 60 days old and have a flatness of 1/8 inches in 10 feet and a moisture level of 3 percent or lower.
- Permanent power and HVAC systems should be on for two weeks minimum prior to installation.
- Basketball backboards should be up, and inserts/sleeves for volleyball/tennis should be elevated above the concrete to the floor thickness.
- If replacing an existing surface (carpet/VCT), the surface needs to be removed and the slab cleaned of adhesive residue or floor remnants by shotblasting or beadblasting to ensure proper adhesion of the new surface.
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