Page 76 - Construction Waterproofing Handbook

BELOW-GRADE WATERPROOFING 2.39
and floor-wall junctions. Figure 2.49 details a typical below-grade application using fluid
membranes. Fluid materials are self-flashing, with no other accessories required for tran-
sitions into other building envelope components. However, a uniform 50–60 mil is diffi-
cult to control in field applications, and presents a distinct disadvantage with fluid systems.
These systems contain toxic and hazardous chemicals that require safety protection dur-
ing installation and disposal of materials. Refer to Chap. 14 and the discussion on V.O.C.
materials.
Fluid-applied systems are available in the following derivatives: urethane (single or
two-component systems), rubber derivatives (butyl, neoprene, or hypalons), polymeric
asphalt, coal tar, or asphalt modified urethane, PVC, and hot applied systems (asphalt).

Urethane
Urethane systems are available in one- or two-component materials. Black coloring is
added only to make those people who believe waterproofing is still “black mastic” com-
fortable with the product. Urethanes are solvent-based, requiring substrates to be completely
dry to avoid membrane blistering.
These systems have the highest elastomeric capabilities of fluid-applied membranes,
averaging 500–750 percent by standardized testing. Urethanes have good resistance to all
chemicals likely to be encountered in below-grade conditions, as well as resistance against
alkaline conditions of masonry substrates.

Rubber derivatives
Rubber derivative systems are compounds of butyls, neoprenes, or hypalons in a solvent
base. Solvents make these materials flammable and toxic. They have excellent elastomeric
capability, but less than that of urethane membranes.
Rubber systems are resistant to environmental chemicals likely to be encountered
below grade. As with most fluid membranes, toxicity requires safety training of mechan-
ics in their use and disposal.

Polymeric asphalt
A chemical polymerization of asphalts improves the generic asphalt material qualities suf-
ficiently to allow their use as a below-grade waterproofing material. Asphalt compounds
do not require drying and curing of a masonry substrate, and some manufacturers allow
installation of their asphalt membranes over uncured concrete.
However, asphalt materials are not resistant to chemical attack as are other fluid sys-
tems. These membranes have limited life-cycling and are used less frequently than other
available systems.

Coal tar or asphalt-modified urethane
Coal tar and asphalt-modified urethane systems lessen the cost of the material while still
performing effectively. Extenders of asphalt or coal tar limit the elastomeric capabilities
and chemical resistance of these membranes.
Coal tar derivatives are especially toxic, and present difficulties in installing in confined
spaces such as small planters. Coal tar can cause burns and irritations to exposed skin
areas. Field mechanics should take necessary precautions to protect themselves from the
material’s hazards.