Your Roof Coating Project: What to Expect

October 21, 2014

You’ve decided to embark on a roof coating project, but aren’t sure what to expect. Here are the basics.

Most manufacturers offer two types of roof coating: acrylic, which is water based, and urethane, which is solvent based. They are compatible and can be (and quite often are) used together. Roof coating products fall into one of four categories.

  1. Sealants.
  2. Accessories.
  3. Primers/base coats.
  4. Finish coats.

Sealants and accessories are applied first, and are typically urethane products. Acrylic or urethane base and finish coats follow.

Prepping the roof surface for a coating application is a very involved process. Careful attention should be paid to the presence of rust, wet insulation, open seams, and raised fasteners, as well as dirt, dust, and debris. Repairing deficiencies and cleaning the surface is critical for adhesion and a quality application.

An adhesion test will be performed to make sure the coating will bond to the existing roof system. If the coating and roof surface do not bond properly, blisters or delamination result.

The weather can greatly impact the quality of the application. Ideal conditions are low humidity, no wind (especially if spray applying), and Fahrenheit temperatures in the range of lows in the 50s and highs in the 80s.

If the application method of choice is sprayed (vs. roll on), when it’s time for work to begin, post signs to instruct individuals to park their vehicles 200 yards from the building. Wind and overspray is a concern. Screens and fencing can be used to minimize overspray, but vehicles should be relocated as a precaution.

If urethane coatings are applied, expect some odor.

After allowing a minimum of 24 hours for prep materials to cure, a base coat is applied. The base coat must cure 24 hours and, in some cases, has limitations on exposure time. Once the base coat is cured, a finish coat is applied.

Base and finish coat application time varies based on the type of roof, application methods, and products used but generally applying a coating as a reroof option shortens the project duration dramatically.

After the finish coat is applied, ample curing time is necessary. Foot traffic is not recommended for 48 to 72 hours, although it’s preferable to stay off the coated roof entirely.

Maintenance of any roof system is important but once coating is applied, it’s imperative that facility professionals perform regular visual inspections and contract with professionals for routine roof inspections. Preventive maintenance is a must to ensure the longevity of the coating.

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