Page 175 - Construction Waterproofing Handbook

3.64 CHAPTER THREE

FIGURE 3.54 Protected membrane application using brick pavers. (Courtesy of Carlisle Corporation)

FIGURE 3.55 Insulation layer in protected membrane application. (Courtesy of American Hydrotech)

slabs, and deterioration of insulation board and the waterproof membrane. Refer to Figs.
3.57 and 3.58 for an example of these drainage requirements.
For the best protection of the waterproofing membrane, a drainage layer should be
installed that directs water to dual drains or terminations of the application. Water that infil-
trates through the topping slab can create areas of ponding water directly on top of the mem-
brane even if the structural slab is sloped to drains. This ponding can be created by a variety
of causes, including imperfections of the topping slab and protection layer, dirt, and debris.
To prevent this from occurring and to ensure that the water is removed away from the
envelope as quickly as possible, a premanufactured drainage mat should be installed on top
of the waterproofing membrane. The drainage layer can also be used in lieu of the protec-
tion layer.
The drainage system is the same basic system as manufactured for below-grade appli-
cations and discussed in Chap. 2. However, the sandwich membrane drainage systems
have one major difference: they are produced with sufficient strength to prevent crushing
of the material when traffic, foot or vehicular, is applied after installation. A typical
drainage mat is shown in Fig. 3.59.