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Commercial Roofing

Roof Coating Systems—What They Are and How to Calculate Just What You Need

By Dawn Killough

May 10, 2021

A roofer applying a roof coating

Even structurally sound roofs may show the effects of weathering and UV damage. Roof coating systems can help protect and extend the life of existing roofing systems.

What kinds of roof coatings should you consider for your roof? And, just as importantly, how do you know how much coating you need for your roof?

Types of Roof Coatings

GAF offers a variety of roof coating systems made with acrylic, silicone, and polyurethane. Below are the key features of each type of system.

  • Acrylic coatings are an ideal solution for structurally sound roofs in need of restoration. Products such as GAF's RoofMate coating can be used on a variety of substrates to help protect the substrate against weathering and UV damage. Additionally, some acrylic coatings systems are fabric-reinforced for an extra layer of protection.
  • Silicone coatings, like GAF's line of Unisil silicone coatings, help protect the substrate against weathering and UV damage while also providing protection against leaks due to ponding water. Silicone coatings provide strong adhesion to many substrates, and come in both high solid and low solid varieties.
  • Polyurethane coatings, like GAF's line of Elastuff coatings, provide an excellent balance of tensile strength, elongation, and hardness. Their hard finish makes them well-suited for installations that require high abrasion, impact, and chemical resistance.

Calculating How Much Coating You Need

The amount of coating a project calls for will depend on a number of factors, including the type of coating, the size of the roof, the substrate being coated, the specific needs of the building, the goals of the owner, and the desired warranty or guarantee coverage. Installers can refer to GAF's Quick Specs and GAF's Application & Specifications Manuals to determine the number of coats and the dry film thickness required to meet the desired warranty or guarantee term. The application manual is also a great reference to identify proper substrate preparation and application techniques.

GAF has a new resource to help contractors, building owners, and distributors estimate the amount of coating needed for a particular project. According to GAF Product Marketing Manager Dave Rubin, the coverage calculator will help when "a contractor is out in the field or in their distributor's showroom and they need to quickly run a calculation."

The calculator is available to help estimate HydroStop acrylic membrane as well as Unisil silicone products. For Unisil silicone products, the calculator is located on the bottom of the individual product web pages. There's no sign-up required, and the tool is accessible from any device that has Internet, including mobile phones and tablets.

To calculate the amount of coating needed, follow the prompts in the tool. You'll need the following information:

  • Project name (optional)
  • Whether the project is located in Florida (and therefore subject to certain specific local code requirements)
  • Type of substrate
  • Square footage of roof to be covered
  • Linear feet of perimeter
  • Linear feet of curbs and penetrations
  • Parapet wall height in feet
  • Desired warranty period

With the information above, the tool can help estimate the amount of coating, fabric, and flashings needed for a project based on the information provided. The report can be saved as a PDF or printed for your records. (For privacy purposes, none of your project or contact information is stored in the system.)

The calculator provides plenty of additional help to assist customers with their calculations, Rubin says.

"We help guide you through the process and give you information about how to properly measure a roof, if you need some guidance on that," he says. "The menu takes you to our preparation guides that provide detail behind the proper prep work needed before you're ready to apply a roof coating—including if primers are needed, what type of primers are needed, and how to properly clean the roof."

It's important to note that the results provided by the calculator are an estimate of the required amount of coating. The accuracy of the estimate depends on the accuracy of the information entered and is for guidance purposes only. Always confirm quantities prior to ordering and ensure you are following local building code requirements.

Coating Calculations Made Easy

GAF aims to support commercial roof installers and building owners with a quick and easy estimate of how much material they'll need for their project. Installers will still need to reference the Quick Spec and application guides for specific information on substrate preparation, application instructions, coverage rates and required thickness and warranty or guarantee options—but Rubin says GAF hopes to give contractors more confidence in their calculations and make the process simpler.

About the Author

Dawn Killough is a freelance writer in the construction, finance, and accounting fields. She is the author of an ebook about green building and writes for construction tech and green building websites. She lives in Salem, Oregon with her husband and four cats.

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Have you ever thought about building products reducing the carbon dioxide emissions caused by your building? When considered over their useful life, materials like insulation decrease total carbon emissions thanks to their performance benefits. Read on for an explanation of how this can work in your designs.What is Total Carbon?Total carbon captures the idea that the carbon impacts of buildings should be considered holistically across the building's entire life span and sometimes beyond. (In this context, "carbon" is shorthand for carbon dioxide (CO2) emissions.) Put simply, total carbon is calculated by adding a building's embodied carbon to its operational carbon.Total Carbon = Embodied Carbon + Operational CarbonWhat is Embodied Carbon?Embodied carbon is comprised of CO2 emissions from everything other than the operations phase of the building. This includes raw material supply, manufacturing, construction/installation, maintenance and repair, deconstruction/demolition, waste processing/disposal of building materials, and transport between each stage and the next. These embodied carbon phases are indicated by the gray CO2 clouds over the different sections of the life cycle in the image below.We often focus on "cradle-to-gate" embodied carbon because this is the simplest to calculate. "Cradle-to-gate" is the sum of carbon emissions from the energy consumed directly or indirectly to produce the construction materials used in a building. The "cradle to gate" approach neglects the remainder of the embodied carbon captured in the broader "cradle to grave" assessment, a more comprehensive view of a building's embodied carbon footprint.What is Operational Carbon?Operational carbon, on the other hand, is generated by energy used during a building's occupancy stage, by heating, cooling, and lighting systems; equipment and appliances; and other critical functions. This is the red CO2 cloud in the life-cycle graphic. It is larger than the gray CO2 clouds because, in most buildings, operational carbon is the largest contributor to total carbon.What is Carbon Dioxide Equivalent (CO2e)?Often, you will see the term CO2e used. According to the US Environmental Protection Agency (EPA), "CO2e is simply the combination of the pollutants that contribute to climate change adjusted using their global warming potential." In other words, it is a way to translate the effect of pollutants (e.g. methane, nitrous oxide) into the equivalent volume of CO2 that would have the same effect on the atmosphere.Today and the FutureToday, carbon from building operations (72%) is a much larger challenge than that from construction materials' embodied carbon (28%) (Architecture 2030, 2019). Projections into 2050 anticipate the operations/embodied carbon split will be closer to 50/50, but this hinges on building designs and renovations between now and 2050 making progress on improving building operations.Why Insulation?Insulation, and specifically continuous insulation on low-slope roofs, is especially relevant to the carbon discussion because, according to the Embodied Carbon 101: Envelope presentation by the Boston Society for Architecture: Insulation occupies the unique position at the intersection of embodied and operational carbon emissions for a building. 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The input on the far left is a given number of kilograms of carbon dioxide equivalent (CO2e) generated for the flight, from the manufacturing of the airplane, to the fuel it burns, to its maintenance. The output is the flight itself, which creates CO2 emissions, but no durable good. In this case, the only CO2 reduction strategy you can make is to make fewer or shorter flights, perhaps by consolidating visits, employing a local designer of record, or visiting the building virtually whenever possible. Now consider the wallpaper you might specify for your client's building. It involves a discretionary expenditure of CO2e, in this case, used to produce a durable good. However, this durable good is a product without use-phase benefits. In other words, it cannot help to save energy during the operational phase of the building. It has other aesthetic and durability benefits, but no operational benefits to offset the CO2 emissions generated to create it. 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We've prepared a handy chart to help.First, when looking at lower-embodied-carbon substitutions for higher-embodied-carbon building materials or systems (moving from the upper-left red quadrant to the lower-left yellow quadrant in the chart), ensure that the alternatives you are considering have equivalent performance attributes in terms of resilience and longevity. If an alternative material or system has lower initial embodied carbon, but doesn't perform as well or last as long as the specified product, then it may not be a good carbon investment. Another consideration here is whether or not the embodied carbon of the alternative is released as emissions (i.e. as part of its raw material supply or manufacturing, or "cradle to gate" stages), or if it remains in the product throughout its useful life. In other words, can the alternative item be considered a carbon sink? 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By Authors Dawn Killough

August 29, 2024

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A low-slope commercial roofing system is responsible for keeping the elements out of the building. During heavy rain, water with nowhere else to go may pond on the roof. A roof drain prevents water from ponding by providing a way for it to leave the roof, and regular commercial drain maintenance ensures its continued performance.Although commercial buildings may appear to have flat roofs, some roofs have slopes built into the structure or require added slopes, typically achieved with tapered insulation to facilitate water drainage. This slope is designed to guide water to a drain, so it doesn't sit on the roof and damage the roofing system or structure. Standing water can slowly deteriorate certain roofing materials and cause premature degradation, failure, or damage. It can also promote algae and plant growth and attract nuisances such as birds and insects.Guiding Water off the RoofResidential roofs have gravity on their side—water flows down the slopes into gutters that transport it away from the home. Commercial buildings with low-slope roofs have to work a little harder to remove water, which is where roof drains come into play.The roofing system design can help guide water toward the drains. It often involves using tapered insulation such as GAF EnergyGuard™ tapered polyiso insulation. The two most popular tapered boards deliver a 1/8-inch or 1/4-inch per foot slope. This slight slope prevents water from standing on the roof, forcing it toward a drain strategically installed at various low points on the roof with crickets and saddles.Drain placement is particularly essential when the parapet wall sheds water. To help water arrive at the drain line or gutter, tapered crickets are typically installed in corners and between drains to direct the flow and alleviate ponding. This water must flow down the roof side of the parapet wall and follow the roof slope to reach the drain.3 Common Types of Roof DrainsInner DrainsInner drains are connected to sloped pipes under the roof that carry water off the roof and away from the building. They typically rely on gravity and the roof's slope to get water to the drain.ScuppersScuppers are found at the roof's edge, usually installed through a hole in the parapet wall. They're designed to drain water from the roof into a downspout or may extend out from the building to shed water.Siphonic DrainsSiphonic drains feature a baffle that keeps air out and allows water to fill the pipes. Once the pipes are full, the lack of air creates a vacuum that siphons water from the roof at a high velocity. The baffle also keeps leaves and debris from gathering in the drain and causing a blockage.Caring for and Maintaining Roof DrainsInspecting and maintaining roof drains should be part of your regular roof inspections. Because roof drains are located at low points on the roof, it's easy for debris or leaves to build up in these areas. Clearing debris is essential for the drains to function properly. Clogs encourage pools of water to form on the rooftop, which can cause structural issues for the building. Even just an inch of standing water can add thousands of pounds of weight to the roof, reinforcing the need for regular commercial drain maintenance.Advancing Roof Drain Maintenance with TechnologyGAF recently introduced the Steely Drain™. This is a roof drain solution that leverages technology allowing contractors to build their maintenace relationship by setting up building maintenance reminders to contact building owners or facility managers. This contractor-inspired drain is made of 316L marine-grade stainless steel, making it ideal for tough environments that require exceptional corrosion resistance.Steely Drain™ features a QR code etched onto the top that you can scan with your smartphone to instantly view information about the roofing system. This data can include the contact information of the contractor who installed the system, the architect and consultants for the project, and the roofing system details if all information is inputted.This critical data is managed from a convenient GAF-hosted dashboard and plays an important role in the roof's maintenance plan. Contractors can set up and receive email reminders when it's time to perform scheduled roof and drain inspections. The dashboard also eliminates the need for core cuts since every detail of the roofing system is available through the QR code—from the deck type to the cover board, underlayment, insulation type and thickness, to the final membrane.Knowledge Is Key to SuccessWhen properly installed and maintained, roof drains can keep the rooftop free of standing water for many years. Curious to learn more? Explore how the Steely Drain™ can help you with your ongoing maintenance programs. You can also visit the GAF CARE Contractor Training Center to gain additional tips and access valuable training courses that allow you to learn at your own pace.

By Authors Karen L Edwards

August 29, 2024

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