Roof Coatings – Six Types of Roofs that Can Be Coated (and two that can’t)

Roof Coating

A commercial roof coating can be a great option for many building and roof types. Benefits of roof coatings compared to roof replacement include significantly lower cost, eco-friendly, less noise, much less mess, extreme waterproofing, extreme UV resistance, and the result is a seamless (vs seamed) roof system. It is no wonder that flat roof coatings have gained so much popularity.

But can roof coatings be applied to any roof? Actually, no. Only certain types of roofs are eligible for coating. And those that are eligible must meet certain requirements before a certified roof coating contractor will agree to coat it.

What Type Of Roof Is Eligible for Roof Coating?

There are six roof material substrates that make great roof coating candidates. They are:

  1. Modified Bitumen – is an asphalt-based rolled-roofing material that performs great with a coating. When coating with silicone, an asphalt bleed-blocking primer is recommended to be installed before the topcoat is applied.
  2. EPDM – is a rubber-based single-ply material found on many commercial buildings. EPDM roofs are great for coating after a rinseable primer is applied and washed, and single ply primer is applied.
  3. Metal roof – perform excellent when coated by a professional contractor. Extra care must be applied to the seams, screws, and penetrations, however. And if there is rust on the roof, a special primer needs to be installed before the coating material.
  4. TPO – thermos-plastic single-ply roof material. TPO is the most common roof material being installed on commercial buildings at present. A single-ply primer should be installed first, followed by the coating material.
  5. Built-up roofing – BUR (aka “tar and gravel”) can be coated under certain circumstances. BUR roofs can also be repaired using silicone coating material. The gravel must be scraped from the coating area, and bleed-blocking primer must be installed. BUR is usually only eligible for a coating warranty if spray foam roofing is applied. New coating materials such as Castagra Ecodur can also be used on BUR, including with warranty.
  6. Spray foam roofing – is one of the best roofing surfaces for a silicone coating. SPF roofing is typically applied over an existing roof and provides a waterproof layer, while the silicone (or acrylic) provide protection from UV.
Silicone Roof Coating
Silicone Roof Coating Before and After

How To Determine Roof Coating Eligibility

Just because you have one of the six roof types above does not automatically mean your roof can be coated. A certified roof coating applicator should inspect your roof to determine if your roof is a good candidate for a roof coating.

Some of the criteria to determine roof coating eligibility are:

  • Wet insulation – if there is a leak in the roof that has soaked existing insulation board, the insulation must be replaced with dry before the roof can be coated. Wet substrate can result in a failed roof coating system
  • Coating material adhesion – many times, an adhesion test is performed to ensure the coating material will “stick” to the roof. Coatings that don’t adhere to the roof surface can create a roof failure later.
  • Coating over prior coating – if the roof has already been coated with silicone, then silicone must be used going forward. Silicone cannot be re-coated with other materials (but performs well with silicone re-coats).
Silicone Coating
Roof Coating Before and After

What Type Of Roofs CANNOT Be Coated?

Certain types of roofs simply cannot be coated. Those include:

  1. Asphalt shingles – shingle roof systems are not eligible for roof coatings. The uneven surface shingles are designed with does not allow roof coatings to be applied in a seamless manner.
  2. Tile roofs – tiles are often nailed under the overlapping rows, and have air gaps in-between rows and columns of tile. The presence of the air gap prevents coatings from working on tile roof systems. This is true for different types of tile including concrete, clay, and synthetic.

Should A Professional Be Hired To Install Your Roof Coating?

Commercial roof coatings are simple to understand, so some building owners have attempted do-it-yourself approaches. Unfortunately roof coating is not a great DIY project because the true installation techniques are multi-layered and more complex than they seem.

We recommend hiring a professional for your roof coating. The steps involved in a long-lasting roof coating include:

  • Surface preparation – this includes repairing the existing roof to ensure the coating will hold firm for decades. Surface preparation also includes a thorough cleaning of the roof to remove debris that can prevent coating adhesion.
  • Primer application (and rinse/reapply) – Most roof coating systems require one (or more) layers of primer to be installed at just the right thickness. Without a correctly installed primer, the coating can fail in multiple ways.
  • Seams and Flashings – after the primer layers but before the main coating, the roof seams and flashings require special attention. Seams should be coated with thick-grade roof coating.
  • Coat the roof – this is when the roof is fully coated with either spray-rig or rolling machines. Experienced coating technicians know how to install the coating to the right thickness, which is critical to the success of the roof to last long-term.

Wrapping Up

When you are ready to get started on your roof coating, contact our team to get started!