Page 186 - Construction Waterproofing Handbook

ABOVE-GRADE WATERPROOFING 3.75
seams that emphasize the 90%/1% principle. Liquid applications are seamless and can prevent
the problems associated with sheet-good installation in small planter areas.
Selection of a protected system should be based on the same performance criteria as
those for materials used with below-grade applications. For example, cementitious systems
are rigid and do not allow for structural movement. Sheet-goods have thickness controlled
by premanufacturing but contain seams; liquid-applied systems are seamless but millage
must be controlled. (See Table 3.23.) Refer to Chap. 2 on below-grade systems for more
specific information.

TABLE 3.23 Protected Membrane Properties

Advantages Disadvantages
Excellent elastomeric capabilities No access for repairs
Topping provides protection Requires drainage at membrane level
No maintenance No remedial applications

FIGURE 3.74 Drainage system for sandwich-slab application. (Courtesy of TC
MiraDRI)

PROTECTED MEMBRANE APPLICATION

Guidelines for protected membrane installation are the same as for below-grade materi-
als. Concrete surfaces must be clean and free of all lattice, dirt, and oils and must be
properly cured. Most systems prohibit the use of curing agents or form-release agents.
Applications follow below-grade installation methods (see Figs. 3.74, 3.75, and 3.76).
Refer to Chap. 2 for specific installation details. With protected membrane installations,