How Much Kool Seal Will I Need to Cover My Roof?

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Prepare the roof thoroughly before applying Kool Seal.
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Kool Seal is a brand of roof coatings frequently used on metal roofs, mobile home roofs and recreational vehicle, or RV, roofs. The product may also be appropriate for flat roofs, depending on which formulation you use. Kool Seal is not difficult to apply to existing roofs and helps block hot summer sun from penetrating through the roof into the home. The proper application amount is determined primarily by which Kool Seal product you use, as well as the roof's composition, condition and size.

Kool Seal White Elastomeric Coatings

Kool Seal White, Premium White and Xtra-Lite Premium White elastomeric roof coatings provide a rubber-like coating that dries to the touch in four to six hours. All three types of coating require two coats, applied at least 24 hours apart. Xtra-Lite Premium's drying time may vary, as it requires temperatures above 77 degrees Fahrenheit and relative humidity of 55 percent or higher to dry properly. For all three products, allow one gallon of roof coating for every 80 square feet of corrugated metal roof or 100 square feet of smooth metal roofing. One gallon will cover 50 square feet of foam or modified bitumen roofing, concrete or bonded tar-and-gravel roofing. Highly porous concrete roofs may require more coating for proper coverage. Kool Seal White is also available as Kool Seal Black and Kool Seal Gray elastomeric roof coating. All deliver the same coverage per gallon.

Duralite White

Kool Seal's Duralite White elastomeric roof coating eliminates the need for primer in most instances, and it resists mildew and algae. The product forms a rubber-like surface that reflects 90 percent of the sun's rays, according to the company's website. One gallon covers 80 square feet of corrugated metal roof and 100 square feet of smooth metal roof. If you have a foam or modified bitumen, concrete, built-up or bonded tar-and-gravel roof, you need one gallon for every 50 square feet of roof surface. Double the amount for all types of roofs to calculate the amount of Kool Seal needed to apply two coats.

Kool Seal RV Rubber Roof Top Coat

Made especially for recreational vehicle roofs, Kool Seal's RV white topcoat rubber roof coating offers the same reflective properties as the company's other white elastomeric roof coatings. Apply Kool Seal RV rubber roof topcoat only when temperatures meet or exceed 77 degrees Fahrenheit and the relative humidity is at least 50 percent. The coating is dry to the touch in four to six hours, but wait 24 hours before applying the second coat. Apply one gallon per coat for every 80 square feet of roof area.

Kool Seal Roof Primer

Kool Seal primers for residential and commercial roofs and primers for RV roofs help prepare the surface so the roof coatings adhere properly. Kool-Lastik Primer is a heavy duty, rubber-like primer that helps seal leaks and correct ponding on problem roofs. The product may be used as a base coat to convert asphalt back to white, as well. While the amount of primer needed per square foot depends on how porous the current roofing is, one gallon of primer covers about 50 to 100 square feet on built-up roofs, asphalt surfaces and modified bitumen roofs. Use one gallon for every 50 square feet of bonded tar-and-gravel roof and for every 50 to 75 square feet of rolled roofing. Kool-Lastik generally covers concrete at the rate of 100 square feet per gallon, but more may be required if the concrete is porous.

RV Roof Primer

Kool Seal RV rubber roof primer is formulated for use on EPDM rubber membrane roofs. Apply two coats, 24 hours apart, but only in temperatures above 77 degrees and relative humidity of 50 percent or higher. The primer covers at the rate of 100 square feet per gallon per coat.

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Audrey Lynn

Audrey Lynn has been a journalist and writer since 1974. She edited a weekly home-and-garden tabloid for her hometown newspaper and has regularly contributed to weekly and daily newspapers, as well as "Law and Order" magazine. A Hambidge Fellow, Lynn studied English at Columbus State University.