Page 189 - Construction Waterproofing Handbook

3.78 CHAPTER THREE
TABLE 3.24 Comparative Characteristics of Horizontal Waterproofing Systems

Membrane system Advantages Disadvantages
Deck coating No protection or topping Maintenance required
Ease of repairs Control of millage
Crack-bridging capabilities Limited color selections
Clear sealers Single-step installation No crack-bridging capability
No protection required Not completely waterproof
No grit or aggregate Highly volatile materials
Membranes No maintenance Protection layer required
Crack-bridging capabilities Interslab drainage required
Applicable over wood and metal No direct access for repairs

high-density insulation board can be used in place of protection board, Fig. 3.77. In these
applications, insulation serves two purposes—protecting the waterproofing during place-
ment of topping and providing insulation value for occupied spaces. Insulation must have
sufficiently high density and compressive strength to withstand the weight of expected live
and dead loads to protect cracking of toppings.
Adequate allowances should be made for movement in toppings, such as control joints
or expansion joints. A water test, by complete flooding of the waterproofing system, must
be completed before topping installation. This prevents unnecessary repairs to water-
proofing after topping installation, should leaks later be discovered.
Most sheet-goods and liquid-applied systems require primers (Fig. 3.78), whereas
cementitious systems do not. Waterproof membranes should not be installed over light-
weight concrete decks such as insulating concrete. These lightweight mixes have insuffi-
cient strength for adequate substrate usage.
Detailing at penetrations is handled the same way below-grade installations require. See
Figs. 3.79 and 3.80 for detailing at penetrations through both structural and topping slab.

HORIZONTAL WATERPROOFING SUMMARY

Advantages and disadvantages of exposed deck coatings, sealers, and protected mem-
branes are summarized in Table 3.24. Once chosen it is important for proper detailing or
terminating into other elements of the envelope to be done with flashings, counterflash-
ings, control joints, or reglets for weatherproof integrity of all systems.

CIVIL STRUCTURE WATERPROOFING

For civil construction projects such as bridges, highway overpasses, and other similar con-
crete structures, waterproofing is often applied more for protection of the substrate and
embedded reinforcing steel than for water infiltration to underlying spaces. Waterproofing
is applied to protect against freeze–thaw cycles, road salt intrusion into the concrete that
attacks the reinforcing, and water infiltration into the substrate that brings along other con-
taminants such as acid rain that can substantially reduce the life cycle of a structure.