This article was published in Frame Building News in June 2020. To view the entire question, click on the cover page above.
The green movement is everywhere now, but many of us were already “green” before the green movement. The post-frame construction industry has been strongly supporting the use of polycarbonate translucent panels to provide daylighting. They use our biggest free resource and use the sun to provide light, otherwise they will need electricity to provide light.
Corrugated translucent panels used in conjunction with popular metal roof profiles have been a cost-effective daylighting solution in many architectural applications, including storage, animal confinement, hobby sheds, and commercial greening. Choosing the right panel to meet the needs of the building may be a difficult decision, because there are many manufacturers, colors and thickness/grade products available on the market.
Corrugated polycarbonate is no longer limited to 0.8mm thick transparent panels designed to span a 2′center; now, the thickness reaches 2.0mm, which can span a 5-foot center, making polycarbonate panels a viable commercial building lighting solution. Just as important as choosing the right product for your application, proper installation and maintenance are essential to ensure extended product life.
The right panel of the application first, determine the required panel configuration file. There are more than 300 configuration files for translucent and metal panels. The corrugated profile you choose should closely match the accompanying metal building panel that the translucent panel will be paired with.
If your application requires the entire roof or sidewall system to be translucent, the profile may not be important. In this case, we recommend that you use the R panel profile to provide you with the most standard thickness and color options. Once the preferred profile is selected, you can use the color and thickness options to move forward.
The heat reflected by reflective silver is 200 times that of a transparent panel. Photo courtesy of Direct Metals Inc.
Transparent panels: These colorless panels can provide up to 90% light transmittance. If you choose to clear, you will get a direct focused beam.
Please note that choosing a transparent panel placed between the metal panels (such as a skylight in a warehouse) can produce a “window frame” effect directly on the floor below-the skylight will create a hot spot, most of which come from the openings concentrated in one area. If your project requires the panels to be transparent, you should choose a transparent panel to make it best for full roof or sidewall applications, such as greenhouse, porch, or pavilion roofs.
Opal white panel and soft white panel: If it is a soft white panel, the light transmittance is between 45% and 85%. These panels are translucent, allowing light to pass through, but it is not clear.
These white panels scatter light and send light in many different directions. This is why white and soft white panels are very suitable for “in-line” skylight applications (such as warehouse skylights), where customers want the best lighting, not the absolute highest light transmittance. The white panel can provide uniform lighting and avoid the “hot spots” that may be generated by the transparent panel.
Special colors: The available types of colored panels include milky white, fog green, bright green, bronze, daylight control silver and reflective silver. Most of these special colors have a transmittance of 20% to 40% and are found in extremely limited profiles.
Although many special colors are only available in 0.8mm thick panels, the latest technology in profiled polycarbonate panel colors is reflective silver panels, currently only available in 2.0mm thick R panels or ridge cap profiles. The heat reflected by these panels is up to 200 times that of transparent panels, which makes the internal temperature of the building lower. This reflective technology and 2.0 mm rigidity make it ideal for warehouse applications in southern and coastal areas hit by sunlight and storms.
The transparent panel can provide up to 90% light transmittance, providing a direct, concentrated light beam. Photo courtesy of Direct Metals Inc.
Panel thickness selection The choice of panel thickness will be determined by your performance expectations. Factors to consider include:
Be sure to refer to the manufacturer’s recommendations to understand the frame requirements needed to support translucent panels of different thicknesses. Many manufacturers specify a 0.8mm panel with 2′center pur spacing, and 1.5mm thick panels have been tested and can withstand a hurricane with a 5′center pur spacing.
Corrugated polycarbonate sheets are usually offered in 0.8mm, 1.0mm, 1.2mm, 1.5mm and 2.0mm sheets. As the thickness of the panel increases, the panel will provide greater resistance to hail, higher snowfall and higher wind pressure resistance. These resistance capabilities may also vary between contours, so if the contour is not important, but the final load capacity is important, we recommend that you use 7.2 corrugated cardboard or a thicker R panel.
The force that conforms to the building code can accurately change the size of the building code, and the size can be as large as the force of a hurricane. The same wind necessitates Florida building codes and standards.
Building regulations encourage the use of higher quality materials, which are expected to increase the stiffness of the structure and extend the life of the building. These standards were quickly designated, adopted or enforced by many coastal cities, counties, and insurance agencies to encourage responsible construction practices.
Examples of code requirements and recommendations include the 2014, 2017, and upcoming 2020 versions of the Florida Building Code, which require wind load testing of structural translucent roof panels. Other governing bodies, such as the Texas Department of Insurance (TDI), also have guidelines and approval systems for translucent panels. If you are building in an area with building regulations, it is recommended that you determine whether the panel selection has an approval or certification number before buying to comply with local building regulations.
Cost issues When choosing translucent products, if you have to weigh the choice between entry-level 0.8mm economical panels and higher-performance 1.0mm, 1.2mm, 1.5mm or 2.0mm panels, it is very important to take the additional cost into consideration The total internal cost of the important roofing system.
Upgrading from the entry-level 0.8 mm to the strongest 2.0 mm, the cost per panel may be three to four times that, but this may only be equivalent to 0.002% of the cost of a 16,000 square foot commercial building.
In order to determine the best value proposition, it is important to understand the customer’s performance expectations. It is also important to consider the total cost of the project, especially if additional purlins must be added to the project, where thicker panels can provide the required structural integrity at a lower cost. When properly installed, the energy-saving effects provided by these panels should exceed the final cost of the installed product.
In warehouses, translucent panels can be a cost-effective daylighting solution. Photo courtesy of Direct Metals Inc.
Installation Tips When installing translucent panels, there are some key processes that can be used to ensure the normal service life of the product:
Sawing, cutting and drilling: Most polycarbonate panels can be cut or sawed by hand or power tools. A desktop/desktop circular saw with a 128-tooth saw blade is preferred, but a portable circular saw can be used in the clamp for on-site cutting. Avoid intersecting cuts-if you must make a cut, drill holes at the intersecting point and saw to that point. Always wear work gloves and protective glasses when cutting, and use gloves to clean rough edges after cooling.
Pre-drilled fastener location: Since the expansion and contraction rate of polycarbonate panels is higher than that of metal panels, it is necessary to pre-drill all fasteners with pilot holes larger than the fastener diameter. The manufacturer recommends that the size of the hole be too large (1/16″ to 1/8″).
There are some winged fasteners on the market that can be pre-drilled and knocked into the wooden substrate, thereby reducing the labor required for proper installation. However, these fasteners work well on thinner 0.8mm panels, but do not work well on 1.5mm and 2.0mm panels. As the hole is too large, it is recommended to use a fastener with a 3/4″ diameter or in some cases a 1 1/8″ diameter gasket to ensure water tightness. Examples of these types of fasteners can be found here.
Panel manufacturers or distributors may need to use specific fasteners, so be sure to check before installing any warranty panels. It is best to use a drill bit specially designed for metal to pre-drill the panel at a drilling speed of 1000 rpm at a 90-degree angle.
Fastener installation and tightening: Do not overtighten the fasteners, otherwise the rubber gasket will be completely compressed. It is best to use an electric screw gun with a torque sensing device and do not hit the driver. Always drive the fastener perpendicular to the surface of the panel until it is secured in place. If the gasket is deformed, the fastener is too tight.
Sealants, adhesives and chemical compatibility: Although polycarbonate panels are resistant to many chemicals, many sealants, paints, coatings, adhesives and insulating backings can be detrimental to the material. The reaction to the sealant may look like spider cracks in the panel, thereby weakening the integrity of the panel. Before installation, it is recommended to consult the manufacturer for a list of pre-tested sealants, adhesives and coatings. If your manufacturer does not provide a list, please find the list here.
In addition to using new sealants, care should be taken to remove old butyl tape and sealant residues in refurbishment applications, and to fold back the vinyl-backed insulation material so that it does not touch the panel. Pay attention to the chemicals used during installation, and use non-ammonia detergents (such as soap and warm water) to clean the panels, which will keep your panels in a good appearance for years to come.
We hope this article can help you avoid the three most common mistakes when selecting and installing translucent panels: choosing a panel too thin, choosing the wrong color for your application, and screwing in the panel without pre-drilling through holes , Like a steel plate. Taking these factors into account, building owners can enjoy years of trouble-free daylighting.
Post time: Nov-13-2020