FAQs: Deck Coating-Skid Resistance & Aggregate


For this month’s first blog post, we revisit our list of frequently asked questions. These are questions we receive on a daily basis from contractors, distributors, architects, consultants, etc., regarding our three product lines: architectural sealants, traffic coatings, and air, vapor, and water resistive barrier systems. This blog post will focus on deck coating. The question is; Are traffic coatings skid resistant, and is an aggregate required?

In 1990, the Americans with Disabilities Act (ADA) was passed as a civil rights law. The purpose of the law is to make sure that people with disabilities have the same rights and opportunities as everyone else” (adata.org). Among other things, the ADA ensures access to the build environment for people with disabilities (access-board.gov). There are ten chapters in total covering applications such as: accessible routes, general site and building elements, plumbing, recreational facilities, and special rooms. Chapter three of the standards set forth by the ADA focuses on Building Blocks. Section 302.1 in particular, concentrates on Firmness, Stability, and Slip Resistance of floor and ground surfaces.

According to the United State Access Board, “Accessible surfaces must be slip resistant to minimize hazards to people with disabilities, especially those who are ambulatory or semi-ambulatory or who use canes, crutches, and other walking aids.  However, the standards do not specify a minimum level of slip resistance (coefficient of friction) because a consensus method for rating slip resistance remains elusive.  While different measurement devices and protocols have been developed over the years for use in the laboratory or the field, a widely accepted method has not emerged…Compliance with the standards requires specifying surface materials, textures, or finishes that prevent or minimize slipperiness under the conditions likely to be found on the surface. Standard practices for minimizing floor or ground slipperiness will likely satisfy compliance with the standards as slip resistance is important not just for accessibility but for general safety as well.”

There is currently no established specification and test method for skid resistance under the American with Disabilities Act (ADA), but the current ADA general recommendation is that static coefficient of friction  (SCOF) be above 0.6 for flat surfaces and 0.8 for ramps. Traffic coatings are designed to meet minimum ADA coefficient of friction (SCOF) recommendations. Although every project is different and there is no hard and fast requirement, there are recommendations that are measurable. “The Occupational Safety and Health Administration recommends that walking surfaces have a static coefficient of friction of 0.5. A research project sponsored by the Architectural and Transportation Barriers Compliance Board (Access Board) conducted tests with persons with disabilities and concluded that a higher coefficient of friction was needed by such persons. A static coefficient of friction of 0.6 is recommended for accessible routes and 0.8 for ramps.”

The problem with claiming a coating is slip resistant is based on the many variables associated with materials that come in contact with a coating surface. Examples of variables include: the tire surface profile of a wheelchair, the rubber composition of said wheelchair tire, or the degree of tire wear. Whether it be vehicular or pedestrian, forces such as weight and forward momentum applied between polymer-bearing surfaces all play a role in COF ratings. A wet surface is generally more slippery or has a low coefficient of friction than a dry surface.  Also, the slope or grade involved may be a factor. The lack of control of the many variables outside of the coating design make it impractical and misleading to claim slip resistant properties beyond what the ADA recommendations outline. Click here to read our Pecora Technical Bulletin #82 for specific ADA recommendations.

The use of aggregate in vehicular or pedestrian coatings is for purposes of increasing the COF and thereby reducing the likelihood of skidding or slipping. The use of aggregate also contributes to the coating durability and abrasion resistance. The type and size of aggregate used will be dependent on the specific coating system under consideration. We recommend sand is composed of hard siliceous, durable grains, free from dirt, clay, water soluble and micaceous particles. Ideally sand should contain a minimum of silica dioxide (SiO2) content of 80%, a maximum loss of ignition of 1%,FA a maximum chloride content of 0.03% and maximum moisture content of 0.5%, by weight, when shipped. Ideally sand should have a minimum hardness of 6.5 on the Moh’s scale. Recommended sand are angular, kiln dried, screened, aggregate blends. They are typically supplied in 30, 20, 16 and 12 mesh sizes. The graph below shows typical representative gradations. The values are the percentage passing through the screen size.

We always recommend reading specific product data, contacting a local sales representative, or reaching out to the manufacturer’s technical service department for more detailed recommendations. For specific information on our Pecora-Deck Traffic Coating offerings, please visit our website at https://www.pecora.com/traffic-coatings/, contact our Technical Services department at techservices@pecora.com, or contact your local Sales Representative.

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