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Roof maintenance is one of the most neglected areas in the roofing
industry. This is unfortunate, since it can be one of the biggest money
savers for building owners and one of the most profitable areas for
roofing contractors. And many times, when maintenance of roofs is
contracted, it is not diligently performed.
Asphaltic coatings are the inexpensive traditional solution. They
are composed of asphalt either in a cutback solvent or emulsified in
water. Asphalt membranes serve as a protective coating. However,
asphalt is extremely susceptible to ultraviolet (UV) radiation and is
not long-lasting.
Aluminized asphalt coatings are a more costly solution. They maintain
their popularity because of the reflectivity associated with them.
These oil-based coatings impart a bright silver appearance. Usually
within one year, however, the aluminum pigments oxidize and leave a
dull gray color. This causes the coating to lose its reflective capabilities,
which decreases the energy-saving benefits. The asphalt in these particular
coatings makes them especially prone to UV degradation.
Today, nonconventional, liquid-applied maintenance coatings are
gaining acceptance because of their practicality. Aged modified-bitumen
roofing (MBR) sheets can be used over traditional BUR systems,
as well as over the new single-ply systems, MBR sheets, and
polyurethane foam. These nonconventional synthetic coatings place
virtually no extra weight on the roof deck or its supporting members.
Even though they are initially more costly than their conventional
counterparts, these newer coatings are more effective in the long run,
primarily with ethylene propylene diene terpolymer (EPDM) or aged
BUR and MBR, because they eliminate the need for radical reroofing.
Roofs can be recoated without adding significant weight to the roof
load, and the coatings can be formulated in white to impart increased
reflectivity to the roof.
Besides contributing to longer service life by reflecting UV rays, the
white color keeps the roof surface cooler, which reduces the demand
for air conditioning inside the building. The advantages of longer service
life and decreased energy costs are the driving forces behind the
popularity of reflective roof coatings.
The most distinguishing feature of liquid-applied roof coatings is
that they are elastomeric, or flexible. This flexibility enables the coating
to withstand the movement of the substrate caused by severe |