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Critical Considerations for Working with Windscreens

As one of the most visible elements of any building project, a windscreen adds safety, comfort and style, while optimizing the views.

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Commercial windscreens deliver unobstructed views while diverting wind to create a more enjoyable outdoor experience. While most windscreen systems are capable of handling 10psf wind loads, the Ascent™ Glass Windscreen from Trex Commercial Products is designed for eight times that amount with a qualified wind load of 80psf, allowing for installation at much higher altitudes.

By: Jon Chase, Vice President of Engineering, Trex Commercial Products

There’s nothing like the great outdoors. This mantra rings true no matter the setting – whether camping in a national park or just stepping out of the office for a breath of fresh air.

With the rising popularity of all things al fresco, architects and designers are incorporating open air spaces into virtually every type of building project – from hotels and high-rises to holistic healthcare settings. Playing a vital role in ensuring the comfort and safety of these exterior areas are commercial windscreens.

Laminated glass and an aluminum or steel framing system provides a sturdy, transparent shield for any outdoor amenity in mixed-used, healthcare and hospitality design plans. Fasteners connected to metal railing posts support the glass infill.

As one of the most visible elements of any building project, a windscreen serves a vitally important role by adding safety, comfort and style, while optimizing the very thing that draws people outside in the first place – the views. Beyond wind protection and visual appeal, a windscreen also aids in noise reduction, a key benefit for outdoor spaces in urban areas or alongside busy roadways.

Although windscreens may be one of the last products to be installed, their specification should be considered early in the design process, ideally at concept, as the structure must be designed to support the system. There are several critical aspects to consider when specifying a windscreen system:

Force and Impact

Most importantly, in order to provide a quality, tested and proven safe product, architects must meet the structural and load requirements of the International Building Code (IBC), as well as applicable local codes, when designing, specifying and installing windscreen systems. In most areas windscreens must be able to withstand a concentrated live load of at least 200 punds and must withstand the force of high winds, especially atop multi-story building terraces.

Most commercial windscreen systems are capable of handling wind loads of 10 pounds per square foot (psf). However, products designed for increased wind load allow for installation at much higher elevations. For instance, the Ascent Glass Windscreen from Trex Commercial Products has a qualified wind load of 80 psf (8 times the industry standard), making it ideal for higher applications.

Windscreens are completely customizable to meet the performance needs and safety requirements for any project’s design. The use of tall, thick glass provides a sound barrier, and quality finishes and special coatings can enhance the durability of the windscreen surface.

Materials and Components

An understanding of typical windscreen material properties will help when evaluating conditions and designing new systems.

Windscreen systems are designed and constructed using laminated glass infill and aluminum or stainless steel framing, such as aluminum posts and steel stanchions. Aluminum structural components are corrosion-resistant, lightweight with a favorable strength to weight ratio and are available in a variety of protective finishes from powder-coat to anodize.

Glass selection will be determined primarily by the environment and wind load. The size, thickness and type of glass must comply with building codes, standards and safety requirements. The IBC requires a minimum thickness of quarter-inch for monolithic tempered glass, laminated tempered glass or laminated heat-strengthened glass.

The offering of a snap-fit aluminum post system makes for quick, safe and easy installation. With one side of the post in place, the glass is positioned in front of the system and held in by VHB tape. The tape holds the first pane of glass in while the next piece of glass is installed. The post cover is then snapped in from the non-drop side, safely securing the glass panel in place.

Because the wind load increases at higher altitudes, thicker, heavier glass will be required to withstand the applied wind load. The IBC also requires that glass installed in exterior railing infill panels or balusters in wind-borne debris regions must be laminated to comply with safety glazing impact requirements. Special coatings, interlayers or films can also be added to reduce glare, provide UV protection or increase privacy.

For structural integrity, designers must select the type, grade and class of fasteners required for connections to anchor handrails and railings to other types of construction and that can withstand the project’s specific design loads. Metals that are corrosive or incompatible with materials joined must not be used.

Weatherproofing

Countersunk screw and setting block attachment detail: Flat head screw fastens aluminum setting block to aluminum post.

Weather and waterproofing are important considerations that too often are overlooked during the specification process. Serious issues can develop when different metals intersect with one another and with the outdoor elements. Thus, it is important to separate incompatible materials to prevent galvanic corrosion.

Movement that occurs with changes in temperature must be considered during the design process, as well. Windscreens should be designed to allow for movements resulting from 120-degree F (49o C) changes in ambient and 180-degree F (82o C) surface temperatures. Taking thermal stress into consideration will maintain the structural continuity along the entire windscreen system.

In areas of high annual rainfall, waterproofing is necessary to safeguard the structural integrity of the building. For hurricane regions or areas prone to high winds, modifications may be required to meet local codes.

Installation

An aluminum post system with snap-fit pressure plate secures glass, and a snap-fit cover plate conceals all fasteners.

When it comes to installation, traditional glass windscreens often require installers to lift large panes of glass and slide them in from the top of the post system. However, as windscreen systems continue to advance, so do installation methods.

Trex Commercial Products’ snap-fit aluminum posts make for quick, safe and easy assembly. With one side of the post in place, the glass is positioned in front of the system and held in by double-sided foam tape. The tape holds the first pane of glass in while the next piece of glass is installed. The cover is then snapped in from the front, safely securing the half-inch glass panel in place. This simple design reduces the time it takes for a contractor to install the system, which can lower labor costs and help keep a project within or even under budget.

Code Compliance

Several codes and requirements must be considered for windscreen applications. At the minimum, systems must be IBC- and IRC-compliant and tested in accordance with AC439 – Evaluation for Glass Railings and Balustrade Systems. This testing evaluates static strength, impact resistance and wind pressure.

A glass windscreen, such as Trex Commercial Products’ Ascent™ Glass Windscreen shown here at Vertis Green Hills in Nashville, Tenn., is ideal for wind protection and privacy around outdoor pool areas.

If a design includes handrails, compliance with the Americans with Disabilities Act (ADA) Title III requirements for designing handrails for commercial facilities will come into play. Locally, it is important to confirm requirements related to glass railing systems with the building department. Field tests may also be required based on local regulations.

As a supplier, I cannot emphasize enough the importance of working closely with the windscreen manufacturer at the onset of the design process.

In our experience, it’s always beneficial when architects and glaziers enlist the help and expertise of the manufacturer to best understand their options and capabilities, especially when determining weight capacity, structural requirements and code compliance. We’ve seen too many cases where a building’s exterior had to be completely redone due to lack of familiarity with national or local codes.

A knowledgeable partner will be able to provide valuable insight regarding regulations and how they might impact the project scope, logistics and cost. At Trex Commercial Products, we conduct a thorough review of applicable codes and regulations. Then we provide a fully engineered system meeting project specifications and requirements.

Over the years, windscreens have evolved from purely functional features to vital design elements that elevate a building’s overall appeal. Whether you’re looking to create a welcoming rooftop retreat, a relaxing outdoor pool area or a therapeutic healing garden, a well-designed windscreen system can provide wind protection, unobstructed views and a sophisticated aesthetic to any building.

For more information about commercial windscreen systems, visit www.TrexCommercial.com.

 

Jon Chase is Vice President of Engineering for Trex Commercial Products, a national leader in architectural railings for commercial applications. The Minneapolis-based company engineers and markets pre-engineered and custom railing systems and has supplied railing solutions for some of the largest projects in North America from major sports arenas to government projects.

 

Photos courtesy of Trex Commercial Products

July/Aug 2020 Digital Issue

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