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Residential Roofing

The Benefits of Self-Adhered Roofing Systems for Low-Slope Roofs

By Annie Crawford

February 24, 2023

Two-story wood house with flat roof porch featuring cedar beams.

About 82% of homes in the United States have outdoor living areas—many with low-slope roofs. That's nearly 6 million homes that could feature a self-adhered roofing system. Are you taking advantage of the opportunities that these porches, sheds, garages, and carports represent?

The LIBERTY™ SBS Self-Adhering Roofing System is a residential low-slope roofing solution that can help boost your bottom line and help keep customers happy.

System Components

The LIBERTY™ SBS Self-Adhering Roofing System features the LIBERTY™ SBS Self-Adhering Base/Ply Sheet and the Liberty™ SBS Self-Adhering Cap Sheet.

Benefits for Customers

Contractors can help educate customers about the benefits of hiring a GAF-Certified Contractor to install the LIBERTY™ SBS Self-Adhering Roofing System on their low-slope roof.

When talking to a customer, explain how asphalt shingles aren't intended for low-slope roofs. In fact, installing shingles could lead to excess debris, pooling water, and an increased risk of leaks and water damage. When it comes to a mopped roof, explain the increased risks of the hot asphalt, and the unpleasant smell. Plus, you can point out that a LIBERTY™ SBS Self-Adhering Roofing System is typically quicker to install.

Clarify for customers which types of low-slope roofs could benefit from having a self-adhered roofing system — such as garages, sheds, patios, porches, carports, etc.

Customers will likely care about aesthetic benefits, too. The granule-surfaced modified-bitumen roofing system has an attractive, low-profile look and comes in seven popular colors that can help complement GAF Timberline® Shingles (among many others!) installed on their home.

Finally, you can explain that the Liberty™ SBS Self-Adhering Roofing System offers both 10 and 15-year warranties depending on the system that is installed. Click here for warranty details.

Benefits for Roofers

Roofers already have the know-how to install the LIBERTY™ SBS Self-Adhering Roofing System, but adding it to your roofing arsenal also comes with real perks, such as:

  1. Saving on setup and cleanup time compared with a typical mopped SBS roof system.
  2. Expanding your economic opportunities by offering an efficient, quality solution for low-slope roofs.
  3. Convenient installation with no torches, open flames, hot asphalt, bulky equipment, or messy solvent-based adhesives.
  4. Rising above the competition by offering an aesthetically pleasing low-slope solution.

Installation Best Practices

This self-adhered roofing system is a straightforward install—no difficult new techniques, just the roofing basics you've already mastered. Here are some best practices for installing the LIBERTY™ Self-Adhering Roofing System. Remember to always refer to full instructions for proper installation.

Remove Old Roof: Remove the existing roof(s) and inspect the roof deck to determine suitability for the LIBERTY™ Self-Adhering Roofing System. As always, confirm the decking is in sound shape before beginning this or any other roofing project, making sure any damaged deck materials are replaced as necessary.

Prep the Deck: Seal up any seams with roof deck tape (to provide added structural strength and waterproofing protection for your project) and prime the deck using the Matrix 307™ Asphalt Primer, LIBERTY™ Asphalt Primer, or equivalent ASTM-D41 Asphalt primer prior to installing the LIBERTY™ SBS Self-Adhering Base/Ply Sheet.

Cut the Base Sheet: Watch the online instructional video to learn the correct base sheet drip edge allowance, how to account for inside corner transitions, and how many inches to add for cant strips when installing the LIBERTY™ Self-Adhering Roofing System. (A password is required. If you're not already using the GAF Learning Portal, you can register to watch this video and other roofing-focused vocational training videos and courses here). Plus, learn how to stagger your base sheet seams to help prevent water and debris from gathering and to improve overall aesthetic outcomes. Pro-tip: lay out the material before starting the installation, so you can verify measurements and help with a smoother application. Note: For two-ply installations, LIBERTY™ SBS Self-Adhering Base/Ply Sheets are required.

Install the Base Sheet: The beauty of self-adhered durable membrane is that no nails are required (unless the slope is 1:12 or higher, then back-nailing in the selvage edge is required to prevent slippage). To create a strong bond and smooth surface when installing, roll with a weighted roller (~150 lb.) between each layer.

Attach the Metal Drip Edge: Before setting the metal drip edge, determine if you are installing a one or two-ply system. This will determine the location of the metal drip edge. Learn about correct nail type and penetration depth for metal drip edge installation in the video. Along with the knowledge gained from the instructional video, be sure to always follow local code on nail spacing.

Cut the Cap Sheet: Cut the LIBERTY™ SBS Self-Adhering Cap Sheet to a manageable length, and align at the lowest edge of the roof, overlapping and flush with the outer edge of the drip edge, with the selvage edge at the high side of the roof.

Install the Cap Sheet: Thankfully, installing the cap sheet is as easy as aligning, folding, peeling, and rolling. The LIBERTY™ SBS Self-Adhering Roofing System was made to simplify a roofer's life when it comes to residential low-slope roof applications. Watch the cap sheet install demonstration and get pro-tips about cap sheet priming, overlap allowance, end laps and T-joints, and more in the above video.

Grow and Connect with Fellow Roofing Professionals

Ready to build your business with expanded roofing products and know-how? Grow professionally with the GAF Learning Portal. Improve your hands-on skills, business expertise, and product knowledge—all while connecting with fellow roofing pros.

About the Author

Annie Crawford is a freelance writer in Oakland, CA, covering travel, style, and home improvement. Find more of her work at annielcrawford.com.

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Commercial Roofing

Branching Out into Commercial Roof Maintenance for Schools

Commercial roof maintenance programs are a great way to expand your business and build long-term relationships with school facility managers. You may already be offering commercial roof maintenance services, or perhaps you're interested in branching out. Providing roof maintenance to K-12 schools and universities can be a good source of reliable, ongoing work. But you'll need to consider these facilities' nuances.Schools' Current Roof Maintenance ChallengesIn an educational environment, students' safety and comfort come first. Buildings must be secure and functional, and they must provide an atmosphere conducive to learning. Creating this environment starts with the roof, but this can easily be put off or forgotten about as many school facility managers focus on day-to-day maintenance issues. If students and teachers complain about a lack of hot water or classroom temperatures that are too hot or cold, facility managers swiftly address these issues.However, facility managers should prioritize regular roof maintenance in addition to addressing the most immediate facility concerns. Even something like a small leak from deferred roof maintenance can lead to much larger, and more costly repairs, creating headaches for everyone involved, that could have been avoided.The Value of Commercial Roof Maintenance ProgramsThe roof protects everything inside the school—from books and computers to shop equipment and musical instruments. If a roof leaks, many items could suffer damage. At the end of the day, ensuring a quality roof through regular maintenance not only protects everything inside the building, it can also help extend the life of the roof. Moreover, some roofing system manufacturers may require regular roof inspections to maintain warranties or guarantees. A roof maintenance program can meet this requirement, providing inspection records and evidence that any issues were addressed.How to Develop a Maintenance Program for SchoolsA commercial roof maintenance program for schools isn't much different from what you already do for other commercial buildings. And while regular maintenance inspections can be completed anytime, a neglected roof can often end up requiring repairs that need to align with the school's calendar to plan for minimal disruptions to the students. This can cause inconvenient delays, or date changes that could be avoided with regular inspections and maintenance.GAF Senior Product Manager Benjamin Runyan says that it's important to identify the manufacturer of the existing roofing system to ensure you are using compatible products that won't void the warranty or guarantee. "You want to be looking at this from a maintenance standpoint," says Runyan. "What does the roof look like? How was it built? How have they been maintaining it?"To start, Runyan recommends that you inspect the entire roof system and document its condition with photos and notes. Pay particular attention to the more vulnerable areas, such as seams, fasteners, flashings, edge metal, drains, and gutters. Look for cracks, missing roofing materials, evidence of ponding water, or of birds or other animals, and signs of moss or algae. An infrared scan of the roof can determine if any moisture is present and help pinpoint areas that need immediate attention.Your program should include basic tasks such as clearing debris from drains and gutters, removing leaves or branches, and making minor repairs where existing sealants are losing pliability or are showing signs of deterioration. If you identify larger concerns, you can document that with photos and provide an estimate for the repairs. Also, note how long the repairs should take and what products you'll use.Getting Started with SchoolsPreventative maintenance programs aren't just a benefit to the schools, they can also lead to other school roofing work including re-roofing opportunities. If you're ready to add school commercial maintenance programs to your business plan, GAF has the resources you need to get started. Runyan explains, "Your first step should be talking with your GAF Territory Manager as they will likely already have established relationships with school districts, colleges, roof consultants and architects in your service area."From commercial roofing system specifications to WellRoof® Guarantee Extensions, plus roof restoration options, GAF meets all your needs for stepping into the world of educational buildings.

By Authors Karen L Edwards

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Flat roof with hot air welded pvc membrane waterproofing for ballasted system
Building Science

Thermal Bridging Through Roof Fasteners: Why the Industry Should Take Note

What is going on here?No, this roof does not have measles, it has a problem with thermal bridging through the roof fasteners holding its components in place, and this problem is not one to be ignored.As building construction evolves, you'd think these tiny breaches through the insulating layers of the assembly, known as point thermal bridges, would matter less and less. But, as it happens, the reverse is true! The tighter and better-insulated a building, the bigger the difference all of the weak points, in its thermal enclosure, make. A range of codes and standards are beginning to address this problem, though it's important to note that there is often a time lag between development of codes and their widespread adoption.What Is the Industry Doing About It?Long in the business of supporting high-performance building enclosures, Phius (Passive House Institute US) provides a Fastener Correction Calculator along with a way to calculate the effect of linear thermal bridges (think shelf angles, lintels, and so on). By contrast, the 2021 International Energy Conservation Code also addresses thermal bridging, but only considers framing materials to be thermal bridges, and actually pointedly ignores the effects of point loads like fasteners in its definition of continuous insulation: "insulation material that is continuous across all structural members without thermal bridges other than fasteners and service openings" (Section C202). Likewise, The National Energy Code of Canada for Buildings: 2020 addresses thermal bridging of a number of building components, but also explicitly excludes fasteners: "in calculating the overall thermal transmittance of assemblies…fasteners need not be taken into account" (Section 3.1.1.7.3). Admittedly, point thermal bridges are often excluded because it is challenging to assess them with simple simulation tools.Despite this, researchers have had a hunch for decades that thermal bridging through the multitude of fasteners often used in roofs is in fact significant enough to warrant study. Investigators at the National Bureau of Standards, Oak Ridge National Laboratory, the National Research Council Canada, and consulting firms Morrison Hershfield and Simpson Gumpertz & Heger (SGH), have conducted laboratory and computer simulation studies to analyze the effects of point thermal bridges.Why Pay Attention Now?The problem has been made worse in recent years because changes in wind speeds, design wind pressures, and roof zones as dictated by ASCE 7-16 and 7-22 (see blogs by Jim Kirby and Kristin Westover for more insight), mean that fastener patterns are becoming denser in many cases. This means that there is more metal on average, per square foot of roof, than ever before. More metal means that more heat escapes the building in winter and enters the building in summer. By making our buildings more robust against wind uplift to meet updated standards, we are in effect making them less robust against the negative effects of hot and cold weather conditions.So, how bad is this problem, and what's a roof designer to do about it? A team of researchers at SGH, Virginia Tech, and GAF set out to determine the answer, first by simplifying the problem. Our plan was to develop computer simulations to accurately anticipate the thermal bridging effects of fasteners based on their characteristics and the characteristics of the roof assemblies in which they are used. In other words, we broke the problem down into parts, so we could know how each part affects the problem as a whole. We also wanted to carefully check the assumptions underlying our computer simulation and ensure that our results matched up with what we were finding in the lab. The full paper describing our work was delivered at the 2023 IIBEC Convention and Trade Show, but here are the high points, starting with how we set up the study.First, we began with a simple 4" polyisocyanurate board (ISO), and called it Case A-I.Next, we added a high-density polyisocyanurate cover board (HD ISO), and called that Case A-II.Third, we added galvanized steel deck to the 4" polyiso, and called that Case A-III.Finally, we created the whole sandwich: HD ISO and ISO over steel deck, which was Case A-IV.Note that we did not include a roof membrane, substrate board, air barrier, or vapor retarder in these assemblies, partly to keep it simple, and partly because these components don't typically add much insulation value to a roof assembly.The cases can be considered base cases, as they do not yet contain a fastener. We needed to simulate and physically test these, so we could understand the effect that fasteners have when added to them.We also ran a set of samples, B-I through B-IV, that corresponded with cases A-I through A-IV above, but had one #12 fastener, 6" long, in the center of the 2' x 2' assembly, with a 3" diameter insulation plate. These are depicted below. The fastener penetrated the ISO and steel deck, but not the HD ISO.One visualization of the computer simulation is shown here, for Case B-IV. The stripes of color, or isotherms, show the vulnerability of the assembly at the location of the fastener.What did we find? The results might surprise you.First, it's no surprise that the fastener reduced the R-value of the 2' x 2' sample of ISO alone by 4.2% in the physical sample, and 3.4% in the computer simulation (Case B-I compared to Case A-I).When the HD ISO was added (Cases II), R-value fell by 2.2% and 2.7% for the physical experiment and computer simulation, respectively, when the fastener was added. In other words, adding the fastener still caused a drop in R-value, but that drop was considerably less than when no cover board was used. This proved what we suspected, that the HD ISO had an important protective effect against the thermal bridging caused by the fastener.Next, we found that the steel deck made a big difference as well. In the physical experiment, the air contained in the flutes of the steel deck added to the R-value of the assembly, while the computer simulation did not account for this effect. That's an item that needs to be addressed in the next phase of research. Despite this anomaly, both approaches showed the same thing: steel deck acts like a radiator, exacerbating the effect of the fastener. In the assemblies with just ISO and steel deck (Cases III), adding a fastener resulted in an R-value drop of 11.0% for the physical experiment and 4.6% for the computer simulation compared to the assembly with no fastener.Finally, the assemblies with all the components (HD ISO, ISO and steel deck, a.k.a. Cases IV) showed again that the HD ISO insulated the fastener and reduced its negative impact on the R-value of the overall assembly. The physical experiment had a 6.1% drop (down from 11% with no cover board!) and the computer simulation a 4.2% drop (down from 4.6% with no cover board) in R-value when the fastener was added.What Does This Study Tell Us?The morals of the study just described are these:Roof fasteners have a measurable impact on the R-value of roof insulation.High-density polyisocyanurate cover boards go a long way toward minimizing the thermal impacts of roof fasteners.Steel deck, due to its high conductivity, acts as a radiator, amplifying the thermal bridging effect of fasteners.What Should We Do About It?As for figuring out what to do about it, this study and others first need to be extended to the real world, and that means making assumptions about parameters like the siting of the building, the roof fastener densities required, and the roof assembly type.Several groups have made this leap from looking at point thermal bridges to what they mean for a roof's overall performance. The following example was explored in a paper by Taylor, Willits, Hartwig and Kirby, presented at the RCI, Inc. Building Envelope Technology Symposium in 2018. In that paper, the authors extended computer simulation results from a 2015 paper by Olson, Saldanha, and Hsu to a set of actual roofing scenarios. They found that the installation method has a big impact on the in-service R-value of the roof.They assumed a 15,000-square-foot roof, fastener patterns and densities based on a wind uplift requirement of 120 pounds per square foot, and a design R-value of R-30. In this example, a traditional mechanically attached roof had an in-service R-value of only R-25, which is a 17% loss compared to the design R-value.An induction-welded roof was a slight improvement over the mechanically attached assembly, with an in-service value of only R-26.5 (a 12% loss compared to the design R-value).Adhering instead of fastening the top layer of polyiso resulted in an in-service R-value of R-28.7 (a 4% loss compared to the design R-value).Finally, in their study, an HD polyiso board was used as a mechanically fastened substrate board on top of the steel deck, allowing both layers of continuous polyiso insulation and the roof membrane to be adhered. Doing so resulted in an in-service R-value of R-29.5, representing only a 1.5% loss compared to the design R-value.To operationalize these findings in your own roofing design projects, consider the following approaches:Consider eliminating roof fasteners altogether, or burying them beneath one or more layers of insulation. Multiple studies have shown that placing fastener heads and plates beneath a cover board, or, better yet, beneath one or two layers of staggered insulation, such as GAF's EnergyGuard™ Polyiso Insulation, can dampen the thermal bridging effects of fasteners. Adhering all or some of the layers of a roof assembly minimizes unwanted thermal outcomes.Consider using an insulating cover board, such as GAF's EnergyGuard™ HD or EnergyGuard™ HD Plus Polyiso cover board. Installing an adhered cover board in general is good roofing practice for a host of reasons: they provide enhanced longevity and system performance by protecting roof membranes and insulation from hail damage; they allow for enhanced wind uplift and improved aesthetics; and they offer additional R-value and mitigate thermal bridging as shown in our recent study.Consider using an induction-welded system that minimizes the number of total roof fasteners by dictating an even spacing of insulation fasteners. The special plates of these fasteners are then welded to the underside of the roof membrane using an induction heat tool. This process eliminates the need for additional membrane fasteners.Consider beefing up the R-value of the roof insulation. If fasteners diminish the actual thermal performance of roof insulation, building owners are not getting the benefit of the design R-value. Extra insulation beyond the code minimum can be specified to make up the difference.Where Do We Go From Here?Some work remains to be done before we have a computer simulation that more closely aligns with physical experiments on identical assemblies. But, the two methods in our recent study aligned within a range of 0.8 to 6.7%, which indicates that we are making progress. With ever-better modeling methods, designers should soon be able to predict the impact of fasteners rather than ignoring it and hoping for the best.Once we, as a roofing industry, have these detailed computer simulation tools in place, we can include the findings from these tools in codes and standards. These can be used by those who don't have the time or resources to model roof assemblies using a lab or sophisticated modeling software. With easy-to-use resources quantifying thermal bridging through roof fasteners, roof designers will no longer be putting building owners at risk of wasting energy, or, even worse, of experiencing condensation problems due to under-insulated roof assemblies. Designers will have a much better picture of exactly what the building owner is getting when they specify a roof that includes fasteners, and which of the measures detailed above they might take into consideration to avoid any negative consequences.This research discussed in this blog was conducted with a grant from the RCI-IIBEC Foundation and was presented at IIBEC's 2023 Annual Trade Show and Convention in Houston on March 6. Contact IIBEC at https://iibec.org/ or GAF at BuildingScience@GAF.com for more information.

By Authors Elizabeth Grant

November 17, 2023

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Commercial Roofing

Questions to Ask a Roofer for Your Commercial Roof Project

If your commercial building needs a new roof or repair, it might be time to call in a professional roofer. You might have a few contractors in your area, so knowing what questions to ask a roofer can help you find the right one for the job. In addition to requesting examples of their past work, here are eight questions to ask a roofing contractor before hiring them.1. Are You Licensed and Insured?Not all states require licensing but many do, and you'll want to see proof that the contractor is licensed in the state they'll be performing work for you.In many cases, roofing contractors who advertise their services are required to include their license number in the advertisement. Most states that require licensing have online portals where you can verify that the contractor's license is in good standing.Insurance is also important, as sometimes not all jobs go smoothly. The contractor should be covered in case an unfortunate incident occurs.2. Does Your Company Hold Manufacturer Certifications?Roofing manufacturers may offer several certification levels, helping you know what level of service and experience to expect. For instance, GAF Master Select contractors are required to complete ongoing training and be properly licensed and insured. Additionally, they must have at least $1 million in general liability insurance coverage and a satisfactory Better Business Bureau rating, among other requirements.Not every contractor can achieve certification. In fact, only 1% of roofing contractors in the US achieve the GAF Master Select status. This status means the contractor has been vetted by the manufacturer, meets strict requirements for quality control and can potentially offer enhanced warranties on roofing systems.3. Are Your Workers Certified?Many training programs and certifications are available for roofing installers, such as the National Roofing Contractors Association ProCertification® training program and the GAF CARE Contractor Training Center.You want to be sure the people working on your roof understand the proper repair and installation methods for your roofing system. Seeing what certifications they hold can confirm their roofing knowledge and familiarity with the products you're looking to install.4. Is Your Company a Member of Any Industry Associations?Membership in an industry association can demonstrate a roofing contractor's professionalism and commitment to their industry. In addition to regional, state, or national roofing associations, some commercial roofing contractors belong to associations designed for building owners and facility managers, such as the Building Owners and Managers Association or the International Facility Managers Association.If you're a member of either of these organizations, your membership list could be a good place to start your search for a commercial roofer.5. What Is Your Project Timeline and Process?The contractor should consider all aspects of your project when planning it. Ensure they'll install quality roofing systems and solutions, and share any concerns you may have—before work begins. For instance, you may be concerned about how construction may affect building occupants, including noise levels and parking. Your contractor should be able to review a plan with you that addresses these concerns.They should also give you a project timeline from start to completion and be able to explain their process, which can include:Initial site inspectionRepair or replacement recommendationsEstimate developmentProject timelinePlans to minimize disruptionsHow they'll handle and communicate unexpected issuesWarranty options6. How Do I Prepare for the Roofing Project?Determine if you need to take any steps to prepare for the project. For example, your contractor should suggest how to inform building occupants about the upcoming work and how long it will last. Also, if you have neighbors close by or share parking lots, they'll need to be notified too.Every project and building is different, so other preparations may need to happen before the project begins. Your contractor can identify any additional needs as part of their inspection and planning process. In most cases, the contractor will handle precautions—like roping off parking areas or protecting landscaping—and they should communicate that to you before your project begins.7. How Much Will the Project Cost? Are There Contingencies?Most commercial roofing contractors include the project cost in their bid package, but you should also ask about contingencies. A contingency is typically a small percentage of the total project cost that may be included to cover surprises during a roofing project, such as mold or rot. Making unexpected repairs will increase the project's cost. So, understand whether a contingency is included in your estimate so you can financially prepare.8. Do You Have a Maintenance Program for Repair Work?Once your roof has been installed, it's important to take care of it. Ask the contractor if they offer a maintenance program that includes an annual inspection of your roof. This is a great way to assess the health of your roof after a year's worth of weather. Any issues can be addressed before they turn into larger problems.By having a maintenance program in place, you can build a lasting relationship with your commercial roofing contractor and may even be able to extend your roof's warranty. If your contractor participates as a GAF Certified Maintenance Professional® you could be eligible for a 25% warranty extension with the completion of required inspections and proper documentation.Signing with a Commercial Roofing ContractorKnowing what to look for when hiring a roofer is the first step toward a successful project. Now that you know some of the questions to ask a roofer, interviewing them should be more straightforward. Their answers can help you decide if they're the right fit for your project. Keep in mind that it's wise to meet with and interview multiple commercial roofing contractors before signing a contract.Ready to take the next step? Find roofing contractors certified by GAF* in your area and schedule a time to talk about the commercial work you need completed.*Contractors enrolled in GAF certification programs are not employees or agents of GAF, and GAF does not control or otherwise supervise these independent businesses. Contractors may receive benefits, such as loyalty rewards points and discounts on marketing tools from GAF for participating in the program and offering GAF enhanced warranties, which require the use of a minimum amount of GAF products. Your dealings with a Contractor, and any services they provide to you, are subject to the GAF Contractor Terms of Use.

By Authors Karen L Edwards

November 08, 2023

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