Page 146 - Construction Waterproofing Handbook

ABOVE-GRADE WATERPROOFING 3.35

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crevices in a substrate. Long nap rollers should be used with covers having a 4– 2-in
nap. Elastomeric coatings typically require two coats to achieve proper millage. The first
application must be completely dried before the second coat is applied.
Spray applications require a mechanic properly trained in the crosshatch method. This
method applies coating by spraying vertically and then horizontally to ensure uniform cov-
erage. Coatings are then back-rolled with a saturated nap roller to fill voids and crevices.
Brushing is used to detail around windows or protrusions, but it is not the preferred
method for major wall areas. When using textured elastomeric coatings, careful applica-
tion is extremely important to prevent unsightly buildup of texture by rolling over an area
twice. Placing too much pressure on a roller nap reduces the texture applied and presents
an unsightly finish. Textured application should not be rolled over adjacent applications,
as roller seams will be evident after drying.
Coatings, especially water-based ones, should not be applied in temperatures lower than
40°F and should be protected from freezing by proper storage. Manufacturers do not recom-
mend application in humidity over 90 percent. Application over excessively wet substrates
may cause bonding problems. In extremely hot and dry temperatures, substrates are misted to
prevent premature coating drying. Complete curing takes 24–72 hours; coatings are usually
dry to the touch and ready for a second coat in 3–5 hours, depending on the weather.
Coverage rates vary depending upon the substrate type, porosity of the substrate, and
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millage required. Typically, elastomeric coatings are applied at 100–150 ft /gal per coat,
for a net application of 50–75 ft /gal. This results in a dry film thickness of 10–12 mil.
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Elastomeric coatings should not be used in below-grade applications where they can
reemulsify and deteriorate, nor are they designed for horizontal surfaces subject to traffic.

FIGURE 3.18 Elastomeric coating application after preparatory work is completed. (Courtesy of
Innovative Coatings)