Types of Roof Coatings
Roof Coating using GacoRoof products avoids costly flat roof replacements.
50 Year Material Warranty, for all restoration projects.
No Day-to-Day Business Interruptions during construction.
No More Worrying about "Ponding Water" Standing Water Resistant Coatings
Extend the life of your roof at a fraction of the cost of a full flat roof replacement.
EPDM Roofing Systems are an economical install without disturbing day to day business.
TPO Roofing, known as an energy star rated eco-friendly flat roofing option.
See an overview of our commercial roofing service options and comparisons.
PVC Roofing is popular for being heat reflective, lightweight, & eco-friendly
Modified Bitumen is the classic standard in flat roofing, but has recently fallen in popularity.
See an overview of our industrial roofing service options and comparisons.
Why Does The Type of Coating Matter?
Roof coating manufacturers apply many benefits to their liquid-applied roof coating systems. It should be suitable for their intended uses and compatible with materials over which they are to be applied. They should bond tenaciously to the intended substrate and sufficiently flexible to tolerate anticipated movement of the roof substrate.
Some roof coatings are intended for use only over bituminous roof membrane systems, others for metal roof panels, and others for sheet roof membranes and spray polyurethane foam roof systems.
Professional commercial roofing contractors should evaluate the selection of coatings and their respective primers while considering as much information as possible regarding their interactive compatibility and compatibility with the substrate over which the coatings are to be applied.
Why Use Primer?
Primers help with the adhesion of the coating by providing a bond between the surface of a roof and the roof coating. Primers come in many different forms, therefore, the type of primer that should be used is based on the substrate, weather condition, and the type of coating that’s being applied. The manufacturer of the primer should be consulted to determine the appropriate usage of the primer. Priming is not a substitute for the thorough cleaning of a substrate before installation
A primer should never be a substitute for proper roof membrane preparation. The substrate should be cleaned and dried prior to the roof coating application. Therefore, this means that any dust, chalking film, greases or oils should be completely cleaned off the roof prior to the application of coatings. Adding a primer to your roof installation can help extend the lifespan of your roof membrane by ensuring the proper adhesion of the roof coating.
Roof Coating Types
There are nine general types of polymer-based roof coatings. A few of the coatings used by our commercial roofing contractors include acrylic, polyurethane, silicone, and fluoropolymer.
Acrylic roof coatings typically are acrylic blinders dispersed in water and sometimes in solvents with pigments and several proprietary additives. Acrylic roof coatings are a well-established coating with proven performance in a wide range of applications. Acrylic polymers are the most commonly used of the high-performance non bituminous binders. There are many acrylic binders used in the roofing industry to produce products with significantly different properties. Acrylic binders may be selected to enhance adhesion to specific substrates, such as asphaltic surfaces, metal or spray polyurethane foam. Different binders will produce coatings of varying elasticity, hardness, permeability, durability, and so on. Proprietary additives may then be added to perform specific functions or act in a general-purpose fashion over a wide variety of roof substrates and conditions. Because of this formulation flexibility, broad application possibilities, and easy handling and installation, acrylic binders are the predominate elastomeric material used in roof coatings.
Because acrylic coatings are water-based, they typically are sensitive to moisture until they have cured; they at least need to be dry to touch and preferably cured to the point of accepting another coat before they can withstand rain. Once the film has cured, the film becomes more resistant to water. However, most acrylic coatings absorb enough water to create blistering and adhesion issues if the water stands on the cured film for extended periods of time. Most acrylic roof coatings are considered to be breathable and exhibit a typical perm rating of 5.0 to 10.0. All water-based products, including acrylic coatings, are also sensitive to temperatures until they are cured.
Polyurethane coatings can be formulated to provide a wide variety of properties and are developed out of an organic solvent base. Overall, polyurethane binders demonstrate high quality adhesion properties that are compatible with most roofing materials and exhibit high elongation and tensile strength, meaning they are strong and durable. They demonstrate a high chemical resistance to many materials and good water resistance. The cured roof coatings can be used as a significant part of many commercial roof coating systems.
Silicone coatings are typically moisture curing, solvent-based formulations. Silicone coatings demonstrate excellent weather resistance, good water resistance, and good elongation with the low tensile strength to be relatively soft in the cured film. The relative softness in the cured film tends to pick up dirt over time and has modest resistance to foot traffic and physical abuse. The cured film is breathable with perm ratings in the range of around 15. The primary use of a silicone coating in roofing is to provide a protective surface for SPF roof systems. In order to recoat a silicone roof coating, a primer may be required before adding the additional layer of silicone coating.
Fluoropolymer paints have been used in roofing applications as a factory-applied film to metal roof panels. The typical fluoropolymer binder has a solvent base and is applied in a thin film to the metal panel and cured in the factory. Recently, some of the manufactures of the fluoropolymer binders have introduced water-based derivatives of the original polymers, opening up the recoat/restoration market for the technology. Fluoropolymer coatings may be applied over the original fluoropolymer paint finishes and over other roof surfaces, as well.
Fluoropolymer coatings demonstrate weather resistance and modest elasticity, and the colored pigments in the coating allow for the color to last longer and prevent fading. The coating also resists dirt pick up while retaining their solar reflectance well. All of these properties indicate that fluoropolymer coatings typically are used by commercial roofing contractors in finish coats as the last step of the restoration system.
What Do We Use?
As stated before, roof primer is usually used in order to make an optimal and even application of coating - in layman's terms to make the coating stick properly to the roof.
We primarily use GacoRoof for our coatings. That means that on most flat roof surfaces, the need for priming can be eliminated because their product is designed to properly stick to a surface without taking this extra time consuming step.
For roofs that have aged asphalt or black tar, then priming will still be necessary because of the unique nature of these materials. All our coatings are tested 24 hours after application in order to guarantee that the new roof coating is properly adhered (sticks to) the surface.
Why Consider Recoating?
Because all field coatings have limited service lives, recoating existing coatings will be necessary after the coating surface has weathered and is no longer protecting the substrate from further weathering. Existing coatings should be identified and an adhesion test should be performed to provide a determination as to what type of coating should be selected for the recoating process.
Special preparation of weathered surfaces is necessary to address surface chalking, surface cracks or locally peeled coating areas. As with other substrates discussed, cleaning and special primers may be required to ensure the bonding of a new coating to weathered coating surfaces.
Once existing coating surfaces have been properly prepared to receive the new recoating material, the installation of the new coating system should be in accordance with the manufacturer’s recommendations and the following consideration: Only silicone primers and coatings should be used over silicone coatings.
Learn about how Spray Polyurethane Foam can help extend your roof's lifespan.
How Do You Apply a Roof Coating?
There are three common application methods for roof coating that commercial roofing contractors use is an airless spray, a roller and brush or a broom. An airless spray sometimes may lead to problems during installation. Mild winds may affect the uniformity of coating layers even when windshields are used during application. When a roofing contractor oversprays the coating application, it can become a problem as the wind can carry the sprayed droplets and atomized particles of coating onto adjacent buildings and/or into nearby parking lots. Coatings applied via the spray method should be applied in multiple cross-directional layers to ensure proper coverage of the surfaces to be coated. Pumps for airless spray applications should be properly sized to move material through long lines from the container to the point of application.
Rollers are available in varying nap lengths. Depending on the composition of the individual coating, the application may be best accomplished with long-nap rollers, medium-nap rollers or short-nap rollers. Rollers provide a better sense of control over the coating quantities and placement. Specialized rollers may be necessary to ensure full coverage of coating over irregular surfaces or folded standing-seam metal roof panels. The rapid movement of rollers may result in a form of overspray where small droplets disperse from the roller by centrifugal force. This overspray from the roller may cause some damage to the surrounding objects. A solvent-resistant roller should be used when applying a solvent-based roof coating.
All coatings should be applied to properly prepared substrate surfaces. Preferable weather conditions for water-based coatings should be dry with low humidity, and conditions for moisture-cure polyurethanes and silicones should preferably be in high humidity and high temperature. There should be little to no chance for any kind of precipitation during and well after the time of installation. Wind speeds preferably should be less than 6 mph. Ambient temperatures should be moderate, with most coating manufacturers recommending that their coatings be applied with ambient temperatures between 40 F and 100 F. Some solvent-based coatings can be applied at temperatures below 40 F.
Low temperatures lengthen a coating’s cure time. Water-based coatings are particularly susceptible to freezing either before or after application. Excessively high temperatures may result in a rapid cure of the coating and compromise the application of the coating. A commercial roofing contractor should consider installing wind screens for the application process to help control any coating droplets from being carried by wind to unmasked surfaces, adjacent buildings, and parking lots.