Page 186 - Masonry and Concrete

Masonry Construction Techniques
185
MASONRY CONSTRUCTION TECHNIQUES

When water repellents are applied by sprayer, sheets of plastic should
be used to protect adjacent surfaces and landscaping. The application
of water-repellent coatings does not require any special skills or equip-
ment, but manufacturer’s label instructions should be followed for
handling, application rates, cleanup, and disposal. Some products
contain VOCs (volatile organic compounds), the use of which may be
restricted in some areas, and the disposal of which is regulated in
almost all areas.
The surface to which the coating will be applied must be clean and
free of dirt or oils that would prohibit absorption of the coating into
the surface. If general or spot cleaning is necessary, the surface should
be allowed to dry thoroughly before proceeding. The mortar in new
masonry walls (or freshly placed concrete) should fully cure for at
least 28 days before applying a water repellent. Water-based coatings
will have less odor than solvent-based products.
Spray applications should be made only when there is little or no
wind to avoid damage from the spray drifting onto other surfaces.
Regardless of whether the application is by brush, roller, or spray, the
water repellent should be put on the wall from the bottom up with
enough material applied to create a 6-in. to 8-in. rundown below the
contact point. The coating should be allowed to penetrate the surface
for two or three minutes and then reapplied in the same saturating
manner. When the first coat is dry to the touch, or within two hours of
the first application, a second saturating coat can be applied in the
same way as described above.

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