Below are four major types of coatings to be compared to answer the question: what is the best roof coating? The information below comes from a study performed in the early 2000’s, read the study here.
These coatings are emulsified asphalt and consist of asphalt particles dispersed in water; they utilize clay as the emulsifying component. These coatings also contain many types of organic and/or inorganic fibres and fillers to provide extra strength to the coating. These coatings are available in black, brown, or as a reflective coating when titanium dioxide or aluminium pigments are added.
These coatings can be applied at approximately 1.5 gallons per 100 square feet, so they require very little material. They can be “swept on” using a push broom. This application method makes for very easy installation, which is an argument for why this could be the best roof coating.
Acrylic roof coatings
These coatings contain various types of acrylic polymer and are typically formulated to help extend the coating’s life and improve durability. Acrylic coatings are available in a number of colours but are most commonly used as white reflective coatings. Thanks to its durability and low cost, many contractors and facility managers believe this to be the best roof coating.
Acrylic coatings are typically applied in two coats, with the second running perpendicular to the first. 1 gallon per 100 square feet is a good estimate for these coatings, as they do not need to be applied nearly as thick as many other coatings. These coatings can be sprayed or roll-applied. Acrylic coatings generally require a re-coat within 2-3 years of application.
Solvent-based asphalt coatings
Solvent-based asphalt coatings are often also referred to as cutback coatings because the asphalt (solid at room temperature) is “cut back” with a solvent which liquefies the coating. This allows the coating to be easier applied. Cutback coatings are available in asphalt black or an aluminium-finish reflective coating.
Solvent-based asphalt coatings can be applied with heavy-nap rollers are a rate of 1.5 gallons per 100 square feet. This coating type can often have asbestos in the coating, so users need to be cautious when selecting their raw materials.
Solvent-based silicone coatings: the best roof coating
Silicone coatings are typically produced by adding a catalyst and solvents to a silicone base. Because the silicone is a natural material, these coatings are bio-degradable. They can be applied to a roofing system using many different techniques, including spraying or rolling. Silicone coatings are available in many colours, including reflective white and translucent.
Silicone-based coatings can be spray or roller-applied and should utilize a medium-nap roller when rolled. These coatings are applied anywhere from 2 to 3.5 gallons per 100 square feet, depending on the substrate. Silicone has two major advantages over the other four types of coatings that should be considered when searching for the best roof coating: 1) it can resist ponding water for extended periods of time and 2) it can adhere to most substrates without a primer. Because of these two major advantages, silicone is the best roof coating that satisfies both quality and cost-effectiveness.