Defending Against Very Severe Hail

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Longtime fixtures of playgrounds and recreational areas, sports courts have a lot to offer. In addition to providing opportunities for children and adults to participate in physical activities, they can strengthen communities. There are also other benefits when courts are designed to reduce surface temperatures and protect substrate materials.Here's a comprehensive look at the benefits of safe, quality sports courts and the impact innovative pavement coatings can have.Current Challenges with Outdoor CourtsSports court coatings were developed to help address challenges faced at many levels. By enhancing courts' durability and design, communities are provided with tangible solutions that address many of these challenges.Increasing TemperaturesClimate change and the heat island effect in urban areas—where hard surfaces like pavement absorb and retain the sun's heat—have led to higher temperatures, potentially affecting the amount of time people can spend outside. Solutions such as building covered structures can be expensive and require a lengthy design and construction process. Planting trees and other landscaping for shade is effective but can take years to develop.Shrinking BudgetsAt the same time, many schools, municipalities, and community organizations have reduced budgets. Play areas are often seen as inconsequential to curriculum, and it can be easy to defer upgrades or repairs.This has caused facilities to put construction plans on hold and instead search for ways to reduce maintenance costs while extending the useful life of their outdoor equipment and paved surfaces. Staff are tasked with providing options for outdoor activities without investing in expensive equipment or major site renovations.Growing Health ConcernsIn response to these environmental and financial challenges, children have been experiencing less outdoor time and lower physical activity levels. This has been found to play a factor in obesity and mental health. Additionally, regular physical activity for students leads to increased concentration and focus, improved attendance and behavior, and boosts academic performance.Outdoor play is a great way to get physical activity, form relationships, and work through difficulties. In fact, the American Red Cross recommends using play to help children manage their emotions. Many studies have shown the value of structured and unstructured play for children, reporting it helps build social skills and encourages creativity.4 Benefits of Pavement Coatings for Outdoor Sports CourtsSports court surface coatings can address these challenges while providing additional benefits.1. Space FlexibilityTraditional playground equipment or court markings can limit the outdoor space's use. With a rich palette of colorful coatings and designs, pavement coatings can provide opportunities for a variety of activities.For example, four square courts can be embedded in traditional basketball court areas, or unique designs can spark imagination, allowing children to create their own games. Providing both children and adults with fewer constraints in how a space is used can help foster creativity and encourage new forms of exercise and play.Some durable, next-gen pavement coatings may even offer opportunities to create courts that can stand up to vehicular traffic for increased flexibility, providing the ability to turn a court into overflow parking or turning excess parking into a multi-court surface.2. Lower CostsDurable pavement coatings can help reduce maintenance costs, by protecting asphalt and cement from damage, which can reduce cracks and extend the usable life of the asphalt or cement substrate. Additionally, coatings may cost less to install than resurfacing or purchasing new equipment.3. Temperature BenefitsHardscape surfaces absorb heat, which can increase the air temperature near the surface. By incorporating lighter-colored or solar reflective surface coatings, more heat can be reflected off the surface, reducing the temperature of the surface and potentially, the air temperature near the surface. This can result in cooler outdoor spaces for children and adults to play, which may increase the amount of time they can engage in physical activity.4. Increased Activity LevelsStudies have shown that creative outdoor play spaces can help increase activity levels and engagement, especially when the surface temperature of the play area has been reduced. An initiative in Boston, which included creating varied outdoor play courts, led to increased physical activity, improved student behavior, and stronger community relationships. In Los Angeles, similar projects led to a 4% gain in the number of students obtaining an hour or more of physical activity per day and a 7.9% decrease in the number of students considered overweight.How Court Coatings Encourage PlaySchool may be the only opportunity children have to engage in physical activity, sports, and general play. Reports have repeatedly shown that play patterns can change significantly when colorful coatings are used.These coatings can help encourage structured activities and games, like four square or hopscotch, or provide the basis for unstructured activities, such as drawing the school logo or a mural. Students can also learn through these surfaces when the pavement is painted with maps or planets. These coatings can have social benefits as well. Playgrounds with a variety of play options may also lead to decreased injuries and an increase in game participation.How StreetBond® Can HelpWhen assessing whether to add or transform a hardscape into a sports court, look at three main factors: budgets, safety and health concerns, and the value of play.StreetBond® pavement coatings can help schools and community organizations transform their hardscapes into robust play areas while meeting their budget constraints. Coatings can help reduce surface temperatures, protect surfaces, and encourage more creative play, helping communities get healthier while learning to work and live together. Visit the StreetBond® website to explore available products, or email streetbond@gaf.com to get support and discuss specific projects.

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.