Metal fabric is a versatile, sustainable and elegant solution for both new construction and existing structures. As a building material itself, the parameters of metal mesh are relatively straightforward. But applying it to the design of a structure requires a more holistic approach to define an appropriately sound solution. The design teams should be prepared to consider the application, performance criteria, and geographic region of the installation and be aware of common pitfalls when designing with the material.
This elegant design solution using metal mesh is the high-tech Tencent Holdings Ltd. in the Chinese metropolis of Shenzhen. For the cladding of the atrium, architects from NBBJ selected 20,000 square feet of golden, stainless steel metal fabric. Key specification factors were the material’s transparency and breathtaking aesthetic.
Determine the Design Intent and Application
The goal is to determine what you need to accomplish—what are we trying to cover, clad or protect? This will help select the right weave pattern and attachment method for the application. This is also a time to consider the desired characteristics of the metal fabric product to align with the design intent. What is the overall design aesthetic and how should metal fabric contribute to that design?
Define Performance Criteria
Once the application and design intent are laid-out, performance criteria should be well defined. To specify the ideal attachment system, appropriate percent openness for perforation and the correct metal alloy, the following performance factors come into play:
- Durability – Will the location of the installation make the mesh subject to high traffic use and abuse? Is low repair and maintenance important to the customer?
- Sunshading – Are you trying to gain solar mitigation? Metal fabric facades naturally provide sunshading but a tighter weave or strategic positioning of the mesh panels can dramatically decrease heat gain on a building.
- Natural Lighting – The transparency of the weave will provide daylighting and unobscured views to the exterior, but architects can vary the degree of transparency which will increase or decrease natural lighting as needed.
- Protection – What level of architectural or perimeter security is required? Do you just need to deter non-personnel from a certain area or do you need active theft deterrent?
- Ventilation – Some building codes, such as those for parking structures, require specific degrees of transparency to allow for ventilation. While you want a weave pattern that meets your aesthetic needs, you can choose a pattern that meets your parameters for ventilation.
Meet Building Codes and Sustainability Standards
After application, design intent and performance criteria are determined, two final considerations are to know exactly how the selected product will meet applicable building codes and fulfill any targeted sustainability standards. While sustainability standards generally remain consistent within a certain version, design load requirements vary from building to building based upon factors such as building type, location, surrounding topography and mesh height.
For example, when specifying metal fabric to mask mechanical equipment on top of an 860-foot building, ask the engineering team: What will the mesh panel reactions be at this altitude? This will help determine at the get-go whether the substructure requires reinforcement, which can lead to significant budget inflation and major schedule delays.
Avoid Pitfalls
Beyond the advice above, some common areas for mishap and specification mistakes include:
- Scheduling – Engage with your metal fabric supplier early in the design process so that production is in alignment with the Master Schedule and any potential delays or installation challenges can be addressed early on.
- Material Consideration – Determine which alloys are suitable to meet your performance objectives and budget requirements. Material interaction is extremely important to the longevity of an installation as it can lead to a galvanic reaction. This refers to the chemical reaction that occurs when two dissimilar alloys are in electrical contact with one another causing one metal to corrode. For example, if you use stainless steel mesh and galvanized steel for bracketry, galvanic corrosion can lead to staining, streaking and dripping. Ideally, stainless steel should be used for the mesh and bracketry attaching to the structure, but hardware consideration may sometimes be tied to budget. One way to use dissimilar metals while limiting contact between them is by using rubber-backed washers, shoulder washers or Teflon tape.
- Holistic Planning – While metal fabric is a high-performance material, it’s important to thoughtfully consider the project as a holistic system that includes the material, hardware and maintenance that will best contribute to a long lifetime for the installation. Taking the easiest or cheapest solution may reduce the initial cost but could require more maintenance over the lifetime of the project.
Dale Payne, PE, is chief engineer at GKD-USA Inc., Cambridge, Md. For more information about specifying architectural metal fabric and additional resources, visit www.gkdusa.com.