Page 150 - Construction Waterproofing Handbook

ABOVE-GRADE WATERPROOFING 3.39
and installed allowances for movement, both thermal and differential. For cementitious mem-
branes to be integrated into a building envelope, installations should include manufacturer-sup-
plied products for cants, patching, penetrations, and terminations. (See Table 3.15.)
Epoxy
As with acrylics, epoxy coatings are generally not considered true waterproof coatings.
They are not recommended for exterior installations due to their poor resistance to ultra-
violet weathering. Epoxy floor coatings have very high tensile strengths, resulting in low
elastomeric capabilities. These coatings are very brittle and will crack under any move-
ment, including thermal and structural.
Epoxy coatings are used primarily for interior applications subject to chemicals or
harsh conditions such as waste and water treatment plants, hospitals, and manufacturing
facilities. For interior applications not subject to movement, epoxy floor coatings provide
effective waterproofing at mechanical room floor, shower, and locker room applications.
Epoxy coatings are available in a variety of finishes, colors, and textures, and may be
roller- or trowel-applied.
Epoxy deck coatings are also used as top coats over a base-coat waterproof membrane
of urethane or latex. However, low-movement capabilities and brittleness of epoxy coat-
ings limit elastomeric qualities of waterproof top coats. (See Table 3.16.)
Asphalt
Asphalt overlay systems provide an asphalt wearing surface over a liquid-applied mem-
brane. The waterproofing base coat is a rubberized asphalt or latex membrane that can
withstand the heat created during installation of the asphalt protective course. Both the
waterproof membrane and the asphalt layers are hot-applied systems.
Asphalt layers are approximately 2 in thick. These systems have better wearing capa-
bilities due to the asphaltic overlay protecting the waterproof base coating.
The additional weight added to a structure by these systems must be calculated to ensure
that an existing parking garage can withstand the additional dead loads that are created.
Asphalt severely restricts the capability of the waterproof membrane coating to bridge

TABLE 3.15 Cementitious Deck-Coating Properties
Advantages Disadvantages
Excellent bonding to concrete substrates No movement capabilities
Good wearing surfacing Not applicable over wood or metal
Dry-shake and power-trowel applications Not resistant to acid rain
and other contamination

TABLE 3.16 Epoxy Deck-Coating Properties

Advantages Disadvantages
Excellent chemical resistance Brittle; no movement capability
High tensile strength Trowel application
Variety of finishes, colors, and textures Not for exterior applications