How to Kool Seal a Roof

Written by audrey lynn
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How to Kool Seal a Roof
Kool Seal roof coatings protect and insulate. (hot tar, roofing image by Greg Pickens from

Kool Seal is a brand of reflective roof coating that helps insulate and seal certain types of roofs. Kool Seal comes in two varieties, aluminium and Elastomeric. Neither compound is made to work on common shingle roofs. Use Kool Seal Aluminum Roof Coating to cover metal, asphalt, modified bitumen, rolled roofing and aged aluminium coated roofs. Use Kool Seal Elastomeric coating on metal, concrete, brick flat and barrel cement tile, foam and aged aluminium surfaces. Kool Seal roof coatings are reflective and add an extra layer of insulation and waterproofing to the roof.

Skill level:
Moderately Challenging

Things you need

  • Stiff broom or long-handled scrub brush
  • Pressure washer
  • Trisodium Phosphate
  • Water
  • Bucket
  • Kool Flex reinforcing grid
  • UV resistant black patch and coat
  • Kool Seal Elastomeric or Aluminum reflective coating
  • Compressor paint sprayer for Elastomeric coating
  • Long-napped paint roller
  • Roofing brush for aluminium coating
  • Ladder

Show MoreHide


  1. 1

    Clean the roof by scraping loose materials and old roofing where needed, then sweep clean of debris. Scrub the old surface with a mixture of water and Trisodium Phosphate, available at paint and hardware stores. Follow label directions for mixing. Apply with a pressure washer.

  2. 2

    Treat mildewed areas with chlorine bleach and water, mixing half and half. Spray or pour the mixture on the mildewed area and allow to dry before moving on to the next step.

  3. 3

    Seal cracks and gaps with UV resistant black patch and coat, and press the Kool Flex grid into the patching material. Apply a second coat of UV resistant black patch and coat to make a watertight seal.

  4. 4

    Apply Kool Seal Elastomeric Roof Coating with a soft roofing brush or long-napped paint roller. Apply smoothly and uniformly in one direction. Allow the first coat to dry completely---four to six hours---then apply the second coat in the opposite direction from the first coat. Do small sections of roof at a time. Elastomeric roof coating may be applied with a paint sprayer, but do not thin the product. Using a tip size of .021 with a 10-inch pattern or .025 for a 12-inch pattern and 2000 PSI, set the unit to spray at the rate of one gallon per minute.

    How to Kool Seal a Roof
    Cover metal roofs with Elastomeric or aluminium Kool Seal for added insulation. (roof image by Andrey Rakhmatullin from
  5. 5

    Mix Kool Seal Aluminum Roof Coating thoroughly before using. Apply to small sections of the roof at a time, using a roofing brush or long-napped paint roller. Allow to dry completely before applying the optional second coat. The coating appears dull until it cures and the surface develops its aluminium sheen.

Tips and warnings

  • Choose a clear, dry day to apply roof coating.
  • Press strips of masking tape to the roof's surface and lift to check for signs of loose dirt before coating. Repeat cleaning if necessary.
  • Clear overhanging branches and vines or other mildew-producing vegetation before applying the new roof coating.

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