How to Apply White Roof Coatings Over Low-Slope Asphalt Roofs

By Chris Huettig, KARNAK Corporation.

KARNAK energy-efficient, acrylic elastomeric white coatings can be applied over low-slope asphalt roofs, but before you get started, it’s important that you understand the proper preparation techniques.

Proper surface preparation will be key to the performance of the coating system. We have written before about the importance of using the right base coat. When applying a white coating system over asphalt, you want to be sure to use KARNAK 405 Bond-n-Shield, a substrate-specific base coat specifically designed and formulated for use over smooth modified, smooth built up and granular modified roofs. This coating improves the adhesion of the white, reflective top coating as well as stops and improves blister resistance and asphalt bleed through. Follow the steps below to install the system or watch this instructional video.

1 – Clean the roof. This is one of the most important steps, as nothing sticks to dirt. Start by using a stiff broom to sweep away dirt and debris. Follow this with power washing using KARNAK 799 Wash-n-Prep.

2 – Prepare and apply 405 Bond-n-Shield. Open the can and mix the product. Pour an amount out onto the roof and using a roller, spread to the rate of 1 ½ gallons per 100 square feet. You’ll notice that the product has a slight blue tint. This tint is added to help you differentiate between the base and top coat when you begin applying the white top coating.

3 – Select a KARNAK top coating (501 Elasto-Brite; 529 Renew White or 535 QS Envirolastic Quick Drying). Remove the lid and mix the product. Be sure to apply the product perpendicular to the base coat using a ¾” nap roller or airless spray equipment.

KARNAK white, reflective coatings will reflect the sunlight and prevent heat penetration into the building, making the interior more comfortable for occupants and can reduce cooling costs.

KARNAK manufactures a full line of coatings, sealants and emergency repair products to meet your customers needs. You can request a free emergency repair kit here.

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