Overview

National Coatings Of Canada Inc explains how commercial roof coatings are applied, including roof preparation, application methods, detail work, coating layers, application rates, and curing.

Highlights

Introduction

If you’ve seen a finished coated roof, the result can look surprisingly simple. The surface appears continuous across broad roof areas and around the many details that interrupt them. Getting to that finished surface, however, takes a deliberate application process.

Commercial roof coatings begin as liquid-applied materials. Depending on the selected system, trained applicators can spray material across the roof, back-roll freshly applied coating where required, address seams and penetrations, incorporate reinforcement, and build the system through successive applications.

Understanding how this process works can help building owners and facility managers evaluate a proposed coating system and the work required to apply it correctly.

What Happens Before Coating Application Begins?

Before the commercial roof coating process begins, the roof has to be ready for the specified system. That can involve inspection, repairs, cleaning, and substrate-specific preparation based on the existing roofing material and its condition. Requirements can also vary across different parts of the roof. Open field areas, seams, fasteners, penetrations, and existing problem areas may require different attention as the project progresses.

Once that work is complete, attention turns to the application. Crews organize materials, equipment, and work areas while accounting for the roof layout and conditions at the job site. This planning prepares the project for the specified application stages that follow.

How Is Commercial Roof Coating Applied to the Roof?

Once the roof is prepared, application follows the specifications for the selected coating system. Depending on the products and layers involved, crews may spray the coating, back-roll freshly applied material, incorporate reinforcement, or use other approved techniques as the system is built.

Professional Spray Equipment Supports Large-Scale Application

Professional airless spray equipment enables trained applicators to apply compatible coatings across large commercial roof surfaces. Rather than mixing the coating with compressed air, an airless unit pressurizes the material and delivers it through a hose to the spray gun. The material then passes through a selected spray tip that produces the required spray pattern.

A commercial spray setup can include an airless spray unit, high-pressure hoses, spray gun, and appropriately selected spray tips. The particular equipment and setup have to be compatible with the coating being installed and its application requirements.

This type of equipment is particularly useful when crews are working across thousands of square feet of commercial or industrial roofing. It provides a continuous supply of coating to the applicator while work progresses across the roof.

For certain coating systems or layers, spray application may be followed by back-rolling while the material is still workable.

Application Methods Can Change Between Layers

A fluid-applied roofing system can involve several stages, and each one may have its own application requirements. One layer may involve spraying and back-rolling, while another may be spray-applied according to the specified technique. Detail products can have other approved application methods, and reinforcement can introduce additional steps where required.

The applicator follows the specifications for each stage, with the application technique changing as the system requires.

How Are Coatings Applied Around Roof Details?

A commercial roof is rarely one uninterrupted rectangle. Vents, stacks, skylights, parapets, drains, seams, fasteners, and other penetrations or transitions can interrupt the open roof field and require focused attention during application.

Fluid-applied materials can follow the geometry of these areas, but the coating still has to be integrated around each detail in accordance with the selected system.

Seams and Fasteners on Metal Roofs May Be Treated Separately

Metal roofing is a good example of the variability of commercial roofs. Panels create seams across the roof, while mechanical fasteners appear repeatedly throughout the surface.

Depending on the coating system, these areas can receive dedicated waterproofing or reinforcing treatment before subsequent coating layers are applied. Reinforcing material may also be incorporated where the system calls for additional support.

This detail work covers far less square footage than the open roof field, but it remains an important stage in building the overall system.

Penetrations Require Careful Application

Vents, stacks, and other penetrations create transitions between the main roof surface and components rising through it. Liquid-applied materials can be worked around these shapes, with reinforcement incorporated where required by the system.

The number and complexity of these details can vary considerably from one building to another. A relatively open roof and one crowded with equipment may have the same total square footage but present very different application conditions.

How Are Commercial Roof Coatings Applied in Layers?

A commercial roof coating system can involve several materials with different jobs. Rather than applying a single product repeatedly, crews progress through substrate preparation, localized waterproofing, base applications, and protective finish coats, depending on the roof and selected system. Not every roof requires every stage. The exact products and sequence depend on the substrate, its condition, and the coating system being installed.

However, the layers can generally perform functions such as:

  • Surface conditioner or primer: Prepares a compatible substrate for subsequent materials by stabilizing or priming the existing surface as required
  • Detail waterproofing: Encapsulates specified seams, fasteners, penetrations, flashings, joints, and repaired areas before broader field applications
  • Base sealer: Creates a continuous waterproof bonding layer in systems that require one and provides a compatible surface for subsequent finish coats
  • Finish coats: Build the weather-exposed portion of the system and provide its final protective and reflective surface

Reinforcing fabric or tape can also be incorporated into wet waterproofing or base materials at designated seams, joints, repairs, and other details. Once embedded and coated, the reinforcement becomes part of that application rather than a separate exposed layer.

The result is a system in which individual materials perform specific functions while bonding together to create the completed roof coating assembly.

What Happens Between Coating Layers?

Coating layers aren't necessarily applied one immediately after another. Depending on the product, each application may need to dry or cure sufficiently before the next stage begins.

Temperature, moisture, humidity, and precipitation can affect this process. Before proceeding, crews may also need to confirm that the previous application is clean, dry, properly cured, and otherwise ready to receive the next layer.

Inspection between stages helps identify application issues before additional coating covers the previous work.

How Is Coating Coverage Controlled During Application?

Commercial roof coatings are typically installed according to specified application rates. An application rate states how much liquid coating should be used over a defined area and gives crews a measurable target while the material is being installed.

For example, a coating specified at one gallon per 100 square feet calls for approximately one gallon of material for each 100-square-foot application area. At that rate, coating 1,000 square feet for a single coat would require approximately 10 gallons of material.

Why Are Application Rates Important?

Application rates tell applicators how much coating to use over a specified area to build the required coating film. Crews can calculate the area being coated and track material use as work progresses, helping them apply enough product to meet the system requirements.

The required rate can also differ between products and layers. A base sealer may have different requirements from a finish coat, while a system involving two finish applications can establish a separate rate for each coat.

These quantities matter because fluid-applied products lose moisture or other volatile components as they dry or cure. What remains is the solid coating film. Applying the specified amount of liquid material helps the completed system build toward its required dry film thickness.

Dry film thickness, often abbreviated as DFT, is the thickness of the coating after it has dried or cured. Where a coating specification establishes a required DFT, application rates and material use provide important controls for building that finished film as intended.

How Does Liquid Coating Become a Seamless Membrane?

Fluid-applied coatings conform to the prepared roof surface and form a continuous film as they dry or cure. Seams, fasteners, penetrations, flashings, and repairs are treated according to the system requirements so these vulnerable areas can be incorporated into the broader coating system.

Base and finish applications then extend across the roof and treated details. As these compatible layers bond and build the specified coating thickness, they form a continuous membrane over the qualifying roof.

This is what makes the system seamless. Rather than installing separate sheets of new roofing with field seams between them, the fluid-applied membrane forms a continuous system across the prepared surface.

See What a Professional Roof Coating Can Do for Your Roof

Commercial roof coating application is a staged process that can involve spraying, back-rolling, reinforcement, detail work, multiple layers, controlled coverage, drying or curing, and inspections as the system progresses. The exact approach depends on the roof and coating system being installed.

National Coatings Of Canada Inc applies commercial roof coating systems for qualifying metal, flat, EPDM, and TPO roofing. With trained applicators, professional airless spraying equipment, and extensive commercial and industrial project experience, our team can approach each roof according to its specific system and project requirements.

To discuss commercial roof coatings for your property, contact us at (519) 323-4597.