With all the hype from the U.S. Department of Energy,
Environmental Protection Agency, California Energy Commission and
others about energy-efficient roof systems, have come a wide
variety of generally acrylic-based white roof coatings out of every
corner of the roofing industry and most corners of the coating and
paint industries. Comparative testing indicates not all roof
coatings are equal—some perform much more admirably than
others. Preparing surfaces to which coatings are to be applied
remains the most important step in the coating process to ensure
relatively long service life. Carefully evaluating surfaces over
which roof coatings are to be applied runs a close second.
Roof coatings are much like paint—the more polymer
"solids" per gallon, the longer the coating's potential life. The
more aluminum "metal" (not paste) in asphalt-based aluminum roof
coatings, the better the potential long-term performance. Likewise,
the more acrylic polymer in a water-based roof coating, the better
the potential long-term performance. But the "best" roof coatings
available will not live up to expectations if surfaces to which
they are applied have not been evaluated for adhesion and surface
preparation does not provide a suitable base for the coating.
Solvent-based coatings are a little more forgiving of improperly
prepared roof surfaces than are water-based coatings simply because
the solvents provide a modicum of "self-priming" properties. Simply
adding a "catalyst" (in two-component coatings) to the coating does
not necessarily ensure better adhesion or weathering
The primary qualities necessary for an...
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