Split-slab Waterproofing in High-load Traffic Environments Designing a high-performing concrete topping slab by Lyn S. Kent, AIA, John F. Sumnicht, SE, and Daniel G. Gibbons, PE All images courtesy Simpson Gumpertz & Heger DESIGNERS OF COMMERCIAL AND INSTITUTIONAL BUILDINGS IN URBAN SETTINGS OFTEN WORK ON CONSTRAINED SITES WHERE THE SERVICE AREAS EXPOSED TO WEATHER OR WASH-DOWN ARE LOCATED OVER OCCUPIED SPACES BELOW. WHILE THE REQUIREMENTS TO PROTECT THESE SPACES FROM WATER INTRUSION ARE UNDERSTOOD AND DOCUMENTED, THIS IS NOT THE CASE FOR THE WEARING SURFACE OVER THE WATERPROOFING SYSTEM, ESPECIALLY WHEN IT COMES TO LOADING DOCKS AND OTHER HIGH-LOAD TRAFFIC ENVIRONMENTS. There are several wearing surfaces that can be used over waterproofing installations, but a concrete topping slab is often the best protection for high- traffic service areas as it can take the abuse and heavy loads. Further, the material is fairly easy to maintain, provided cracks in the slab are minimized. In split-slab applications, the most reliable waterproofing membrane assemblies form a long- term watertight seal over the structural slab substrate. This type of system typically consists of a layering of components such as a waterproofing membrane, a protection layer, and a drainage layer. However, since these systems are compressible, the concrete topping slab must be designed to be placed over top. 22 the construction specifier | january 2013 CS_Jan2013.indd 22 12/12/12 9:33:07 AM