Page 154 - Construction Waterproofing Handbook

ABOVE-GRADE WATERPROOFING 3.43
Chemical resistance can be an important consideration under certain circumstances.
Parking garage decks must have coatings resistant to road salts, oil, and gasoline. A pedes-
trian sun deck may be subjected to chlorine and other pool chemicals. Testing for chemi-
cal resistance should be completed according to recognized tests such as ASTM D-471.
Weathering resistance and ultraviolet resistance are important to coatings exposed to
the elements such as on upper levels of a parking garage. These areas should be protected
by the ultraviolet-resistant properties of coatings such as an aliphatic urethane. Weathering
characteristics can be compared with accelerated weathering tests such as ASTM D-822.
Other properties to consider on an as-needed basis include adhesion tests, solvent odor for
interior uses, moisture vapor transmission, and fire resistance.
Once installed, the useful life of deck coatings depends upon proper maintenance as
well as traffic wear. Heavily traveled parking garage decks and loading docks will wear
faster than a seldom-used pedestrian deck area. To compensate, manufacturers recommend
a minimum of one to as many as three additional intermediate coat applications. Additional
aggregate is also added for greater wear resistance (Fig. 3.20).
With proper installation, deck coatings should function for upward of 5 years before
requiring resealing. Resealing entails cleaning, patching existing coatings as required,
reapplying top coatings, and, if required, adding intermediate coats at traffic lanes. Proper
maintenance prevents coatings from being worn and exposing base coatings that cannot
withstand traffic or exposure.
Exposed and unmaintained deck-coating systems require complete removal and replace-
ment when repairs become necessary. Chemical spills, tears or ruptures, and improper usage
must also be repaired to prevent unnecessary coating damage. Maintaining the top coat or
wearing surface properly will extend the life cycle of a deck-coating system indefinitely.
Deck coatings are also effective in remedial waterproofing applications. If a sandwich-
slab membrane installed during original construction becomes ineffective, a deck coating
can be installed over the topping slab provided proper preparatory work is completed.
Deck coatings can also be successfully installed over quarry and other hard-finish tile sur-
faces, precast concrete pavers, and stonework. With any special surfacing installation,
proper adhesive tests and sample applications should be completed.

FIGURE 3.20 Suggested aggregate texture layout for
maximum protection of deck coating. (Courtesy of
General Polymers)