The Best Coating for Flat Roof

Updated April 17, 2017

Flat roofs leak more than pitched roofs, as they tend to hold water on them. It can be a headache to the homeowner when he is sitting in his front porch relaxing, and rain starts to penetrate through the flat roof above. Flat roofs take weather conditions "head on" because they are directly facing upwards. If not properly maintained, a flat roof will start to crack and lose its elasticity. This eventually results in roof leaks that damage the interior of a house. Maintaining a flat roof with the best coating for the roofs condition and age can greatly extend its life. It can also save you from making costly repairs both inside and on the roof of your house.

Aluminium roof coating

Aluminium roof coating not only protects a flat roof, it also refurbishes the material and reflects the sun. This is the best coating for newer roofs. The surface of the roof is cleaned of all debris with a broom, and the remaining dirt is removed with a yard blower. The cans of coating are shaken well when closed. They are then opened and mixed with a large cement bit attached to a drill. A long handle attached to a paint roller with a 1-inch nap is used to apply the coating. When the roof is completely covered with the product, it is given 24 hours to dry. A second coat is applied for extra protection. The process should be repeated once every 12 months.

Latex Roof Coating

Rubberised roof coating is a latex paint with a rubber additive in it. It is waterproof and aids in reflecting the sun from the roof. This is the best coating for roofs five to 10 years old. The roof must be a smooth surface to apply this process. Debris is removed with a broom, and a pressure cleaner used at 1500 psi to clean the surface. The buckets are shaken up and opened. A paint stick and roller with a 1 3/4-inch sleeve is used to apply the coating. Three coats are applied to the roof, allowing each coat to dry before the next. This coating takes approximately eight hours to dry. The process should be repeated once every eight months.

Cold Process Roof Tar Coating

Cold process roof tar is a liquid version of tar. When applied to a smooth clean flat roof, it coats the surface with a thin tar base and fills in larger cracks. This is the best coating for an older roof with several leaks, as an alternative to a reroof. The roof surface must be clean of all debris and dirt when applying. About a quarter can at a time is poured directly on the roof. The tar is spread out with a throwaway tar broom that has a rubber edge. This process is repeated until the roof is completely covered. This process cures over several months, allowing it to continue to replenish the damaged areas. It should be reapplied once every 12 months.

Polyurethane Foam Coating

Polyurethane coating is a white foam substance similar to plumbers foam. It comes in large pressurised canisters, and is sprayed directly on the roof. This coating is best for older roofs that are not completely smooth. The surface must be clean of all dirt and debris. A latex primer is applied to the entire flat roof. The substance is sprayed on the roof in a slow even motion on 4x4 areas at a time. The thickness of the foam should be approximately 2-inches. This is continued until the roof is completely covered. It takes four hours to cure. A coat of oil based exterior paint is sprayed onto the cured surface. The paint process should be done once every 12 months.

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About the Author

Dan Dechenaux has written since 2009. Specializing in health and sports topics, he contributes articles to The Sports Ad-Visor. Dechenaux received a Master of Arts in communication arts from the University of Notre Dame.