How to Apply Elastomeric Roof Coatings

An elastomeric roof coating can provide an additional layer of protection for existing roof systems, preventing leaks, improving energy efficiency, and extending the lifespan of the roof. However, it is crucial to apply the coating correctly to ensure its effectiveness and avoid costly repairs in the future.

What is an Elastomeric Roof Coating?

An elastomeric roof coating is a liquid-applied coating, typically made from silicone or acrylic, that cures into a durable and highly elastic membrane when it dries. Its elastic nature allows for easy application on various roof surfaces and adaptability to different weather conditions. Elastomeric coatings can be applied to new roofs for additional weatherproofing or to older roofs to seal leaks, reinforce integrity, and extend lifespan.

Suitable Surfaces for Elastomeric Coatings

Elastomeric roof coatings can be successfully applied to a wide range of roofing materials, including but not limited to:

  • Built-up roofing
  • Asphalt
  • Metal
  • Fiberglass
  • PVC
  • APP or SBS cap sheet
  • Aged EPDM or TPO membranes
  • Concrete
  • Exterior-grade plywood
  • Sprayed polyurethane foam
  • Existing elastomeric coatings

Advantages of Elastomeric Roof Coatings

Elastomeric roof coatings offer several benefits that make them a popular choice:

  1. Increased energy efficiency and UV protection: Elastomeric coatings provide a “cool roof” effect, reducing energy bills during hot summer months.
  2. Additional waterproofing and weathering protection: These coatings create a robust shield against rain, snow, ice, and other weather elements. They also reinforce roofs that are exposed to high winds.
  3. Easy repair and maintenance: Vulnerabilities can be easily resealed by applying more coating to damaged areas.
  4. Extended roof life expectancy: A well-applied elastomeric coating can last 10-20 years, restoring and prolonging the viability of the roof.

How to Apply Elastomeric Coatings

To ensure the proper application of elastomeric roof coatings, follow these steps:

Step 1: Gather Appropriate Tools and Equipment

Having the right tools and equipment for the job will make the application process easier and faster. These include goggles, hard hats, work boots, gloves, safety harnesses, solid plastic core roller covers, all-purpose brushes, scissors, mallets, push brooms, power drill with mixer, and sprayer equipment.

Step 2: Clean and Pressure Wash the Roof

Preparation is key to a successful coating application. Before applying the coating, make sure the roof is clean, dry, and structurally sound. Remove all debris and dirt from the roof, using a broom or brush for heavily soiled areas. Clean the entire surface using a power washer with a 30-degree cleaning tip and a pressure of 2,500 to 3,500 p.s.i. Use a push broom to push standing water towards the drains. Allow the surface to dry completely.

Step 3: Repair and Reinforce the Roof

Before applying the elastomeric roof coating, repair any areas of damage. Use Polyglass PolyBrite polyester fabric and mastic to reinforce the repaired areas, as well as areas around roof penetrations, curbs, and rooftop equipment.

To address inside corner details, apply a generous coat of Polyglass base coat to the inside corner, then embed reinforcing polyester fabric into it. Apply more base coat to seal overlapping pieces of fabric and cover the fabric area with a saturation coat.

For outside corner details, apply a generous coat of Polyglass base coat to the outside corner, then embed reinforcing polyester fabric over it. Apply a saturation coat and connect the details with an additional 12-inch piece of polyester fabric.

For pipe penetration details, cut the polyester fabric for the finger flashing to cover and overlap the pipe by at least 3 inches. Apply a base coat around the penetration area and work outward horizontally and up the pipe. Apply the finger flashing around the pipe and an additional base coating to secure it. Fit the target piece over the pipe and apply a saturation coat.

If roof reinforcement is necessary, unroll 40-inch polyester fabric rolls over the base coat, overlapping them by at least three inches. Apply another layer of base coat to seal the fabric.

For metal seam flashing details, apply two coats of Polyglass PolyBrite 77 premium SCBS cement along the seams, with a minimum of 2 inches on each side. Apply an additional dab of cement over the screw heads for complete encapsulation.

Step 4: Conduct a Field Adhesion Test

Perform a field adhesion test on the roof to determine if a primer is needed. Attach a test piece of polyester reinforcing fabric with primer, apply another coat of primer over it, and let it dry for 24 hours. Pull the fabric using the uncoated portion. If the coating comes off clean, a primer may be required.

Step 5: Mix and Stage Roofing Products

Thoroughly mix all Polyglass products, including the elastomeric roof coating, using a 3/4-inch corded electric drill with a power mixer attachment. Make sure all products are kept out of direct sunlight and protected from freezing.

Step 6: Configure Spray Equipment and Apply

For the application of the coating, use airless spray equipment with a minimum capability of 3/4 gallons of volume per minute and a minimum of 3,300 p.s.i. Apply the coating evenly at the specified wet film thickness, keeping the nozzle 12-18 inches from the surface.

By following these steps, you can ensure a proper and effective application of elastomeric roof coatings, increasing the longevity and performance of your roof system.

To learn more about liquid-applied roofing, watch our instructional videos on Liquid Applied Roofing (LAR).

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