Of all roofing designs used in homeowner associations, flat roofs are the most problematic, particularly in rain, wind or snow prone areas. The need for consistent and quality maintenance is extremely important for maximum performance and longest life. Recoating builtup flat roofs is a fundamental preventive maintenance which should be performed at least every five years and included in the reserve plan. There are six reasons for roof coating:

1. To maximize roof service life by reflecting harmful ultraviolet (UV) radiation.
2. To restore a moderately aged roof to a maintainable watertight condition.
3. To restore an earlier coating applications that has deteriorated.
4. To minimize solar gain and reduce a building’s cooling loads.
5. To improve a roof’s appearance that is visible from the ground or from an adjacent building.
6. Certain UL-classified coatings can increase a roof’s flame spread resistance. This type of application typically is specified in conjunction with roof system construction. Flame spread resistance, however, can be upgraded after a roof is in service.

There are at least three situations in which coating is not a good idea:

1. A coating never makes a bad roof good. If a roof has reached the end of its useful life, coating it is a waste of money.
2. Ponded water that remains for more than 48 hours after a rain reduces a coating’s service life. These areas need to be properly repaired to promote positive drainage before applying a coating.
3. Coatings will fail prematurely if they are applied in environments containing excessive dust, debris, steam, liquid discharge or other contaminants. If contaminants can’t be completely removed prior to coating application,
the coating will not adhere or flake off.

Coatings come in a variety of types:
Emulsions. Consist of asphalt dispersed in a colloidal clay-water blend and are dark gray, brown or black. Emulsions generally increase the roof’s fire resistance.

Aluminum. A mixture of oxidized asphalt, solvents and aluminum paste, and they are available with or without reinforcing fibers. Aluminum coatings reflect UV radiation, reducing rooftop temperatures, premature aging and building cooling loads. The quality of these products is measured by the aluminum content, expressed as 1, 2, or 3 pounds of aluminum paste per gallon.

Emulsion-Aluminum. A hybrid product with fire resistance and filling/sealing properties of an emulsion coating.

Asphalt Cutbacks. Consist of asphalt and petroleum solvents. Cutbacks are primarily maintenance and restoration products, designed to penetrate, resaturate and restore weathered or aged asphalt built-up roof systems.

Resaturants. Made with either an asphalt or coal-tar base, it penetrates, rejuvenates and weatherproofs existing built-up roofs.

Modified Asphalt Coatings. Made with asphalt, synthetic rubber polymers and solvents and might contain reinforcing fibers. Advantages include increased elasticity and cold-weather flexibility.

Bituminous Coating. Compatible with asphalt or coal-tar built-up roofs or with modified bitumen membranes.

Elastomeric Coating. Formulated from latex/acrylic, Hypalon, neoprene, silicone or urethane. Many elastomeric coatings are compatible with common roof membranes, but they are more widely used with metal and sprayed-in-place polyurethane foam roofing systems.

Consult with a knowledgeable flat roof maintenance contractor to determine the proper coating for yours. The cost of application is usually modest compared to the cost of replacing the roof. So, like changing your car engine’s oil, make coating your roof a regular event. To dress it up, you can custom color it, just like paint. But make sure to apply it at recommended intervals. This is a recoat of many colors that should not be worn out.