Does Unitization Work for Complex Façades?

By Jordan Scott

Unitization is a trend that continues to grow because it offers quality control, cost savings and installation efficiency. But is unitization possible when designing buildings with unique shapes? Many glazing subcontractors say yes, for a cost.

System Edits

YYK AP America of Austell, Ga., often creates custom unitized systems by modifying its existing systems. Project center manager John McGill says the company rarely makes a brand new system for a specific project.

“If you have an existing or standard system to work with it will be more cost effective and ready in the timeframe needed versus developing a completely custom system,” he says, adding that another benefit is that the manufacturer already knows how that system performs even if a few modifications are made.

Marketing and communications manager Steve Schohan adds that this is especially important in Florida where the product approval process is more difficult than other states. However, testing could be required in other states if significant modifications  are made.

McGill cites early involvement with the architect as important if they want the façade to be unitized, since the anchoring needed could require more clearance than a stick-built system. However, he expects that, in five to ten years, most systems developed by manufacturers will have pre-glazing and unitized options, even for complex geometries and angles.

YKK AP America acquired Erie Architectural Products Group of Lakeshore,
Ontario, in December 2019, a company that’s involved in creating custom unitized curtainwall. Erie vice president Chris Stronks says creating these systems requires finding the perfect balance between the aesthetic drivers from the architect and the performance requirements of the building.

“We will create a custom unitized curtainwall for the right project, but we try to maintain our ENVIRO|FACADES design principles. For example, the air seal in our unitized curtainwall system is a very good seal and proven technology. If a project requires a custom system, we will modify the unitized curtainwall system, but always maintain the critical design principles (like the air seal) sticking with proven technology while customizing the more ‘flexible’ components of the system to suit the customer’s needs,” he says.

Rectangular panels that span from floor-to-floor lend themselves to unitization. Adding complexity to the design increases the challenge for the manufacturer.

“When the designer introduces knuckles/kinks or multi-planar elevations in the façade system, it tends to cause additional challenges for a unitized curtainwall system. Since the vertical mullions need to span from floor-to-floor to make the system work structurally, the knuckle/kinks often cause challenges with that and you end up needing to combine units into much larger panels until the panel can structurally span floor-to-floor,” says Stronks.

Sometimes achieving unitization requires compromise. Stronks explains that for projects such as a midrise tower in New York City or downtown Philadelphia, a good architect or façade consultant would understand the challenges being faced.

“They are often willing to work with us, modify the geometry as required and ultimately allow the project to stay unitized,” he says.

Rob Huffman, director of Kawneer Collaborative for Kawneer Co. of Norcross, Ga., says approximately 80% of his company’s unitized work involves customized solutions and extrusions, ranging from modified stack joints to mullion-less unitized chassis that feature structural glass.

“We start with early involvement to ensure that we have a proper understanding of the architect’s aesthetic requirements. This includes building geometry and system performance requirements. Once we have an understanding, we will review against our chassis portfolio to determine if we have a match and at what percentage,” he says. “This information is presented back to the design team for review and comment. If conditions look favorable, we will schematically develop the remaining percentage. Throughout the process, we use cloud-based tools (i.e. BIM 360) to enhance communication and development.”

He says that, theoretically, unitization is always possible, but it’s not always favorable due to time and cost. Many factors are at play when deciding whether to unitize or not. It often depends upon the perspective of the initiating party.

“An architect may want a unitized solution to garner manufacturer accountability for quality and performance. A contractor may want a unitized solution to compress onsite construction time. A glazier may want a unitized solution due to the resource constraints in their shop. However, these perspectives are often bound by competing factors (i.e., schedule, budget, labor skill set), which might not allow for a unitized solution,” Huffman explains.

Mixed Methods

Kirt Smith, director of engineering at Benson Industries in Portland, Ore., says his company creates custom unitized systems for nearly every project, meaning Benson doesn’t reuse its dies.

“It’s actually more difficult to come up with something that’s not unitized,” he says. “Having a unique geometry, size or shape is what makes unitization more difficult, usually due to shipping. A lot of projects do run up against manufacturing capabilities and limitations in the size of the insulating glass units or the length of the extrusions.”

Smith says that certain scopes of a project may not be unitized due to its complex geometry, especially projects involving shifting horizontal or offset grid patterns. In those cases, more of the tower will be unitized while the setback will be stick-built.

“We try to do as much as we can offsite by using ladder frames or cassette systems so the glass is already glazed to a frame that just needs to be attached to the system,” he explains, adding that Benson does most of its work offsite in a controlled environment to speed up onsite product delivery. “There’s value from a quality perspective as well as speed of installation.”

Jeff Haber, managing partner, says his company, W&W Glass in Nanuet, N.Y., prefers to use unitized systems regardless of the geometry if possible due to the quality control, cost savings and ease of installation.

“Typically the tower is entirely unitized regardless of the geometry. We figure it out and modify the frames if necessary and the client pays accordingly,” he says.

Working Together

Budget definitely plays a role in determining how much of a complex project is unitized, says Haber. The other factor is whether or not the various manufacturers involved have the technical ability to solve complex geometries.

“There’s a limit in the [number of] manufacturers that can participate in these types of projects right now. Over time, the technology will become more commonplace and readily available,” he says, likening this process to the evolution of oversized glass in the industry. “Both architects and consultants will get used to it and integrating it into projects and more fabricators will adopt the technology and processes needed. It will become commonplace just in time for someone to change their mind.”

Early collaboration is vital for unitization to be successful.

“Some of the biggest issues that we see occur when architects spend a lot of time with complex geometry, with not as much detail being put into transitions,” says Smith, who adds that it can be difficult to model those complex transition areas.

When those details haven’t been developed, it can conflict with the project schedule.

“It’s a big challenge when we need to be in the fabrication process but the architect still wants to mess with the geometry,” he says. “We have to be on top of documenting any changes that the architect is making that impact our schedule and relaying that to the general contractor. Then the general contractor can work with the owner and architect to limit those changes and adjust the project schedule.”

Smith says this is an example of why it’s extremely important for the glazing contractor to be involved during the design phase. Haber adds that early involvement is not only for the success of the project, but critical for the project’s complex and unique elements.

“The earlier we can get involved, the earlier we can lend our expertise to the design team. We can help them rationalize the geometry and make sure it can be manufactured and implemented into the logistics, installation and sequencing of the project so that it doesn’t become a budget buster,” he says. “There’s always a way to do things it’s just that, at a certain point, you cross a threshold that the client doesn’t want to cross. The earlier you participate with  designers, the better the chances that element stays in the project.”

Facing Forward

Benson’s engineering experience has grown over the 40 years it’s been creating unitized curtainwall. Smith says the company couldn’t have done the buildings it’s doing now back then, and attributes that growth, in part, to software.

“Without the capabilities created through 3D modeling we couldn’t do these projects to the level of accuracy they’re done today,” he says.

Stronks thinks that as computer software, such as Revit, Rhino, etc., continues to advance, it will be easier for the architect to introduce complex geometry and for this trend to advance.

“The proliferation of 3D software and modeling talent is enabling more elaborate designs. The ability to repurpose this design content to develop deliverable goods through robotics and automation is improving manufacturer abilities to supply complex geometric solutions,” adds Huffman.

Smith expects unitization to continue to grow. However, he says there will always be a place for stick-built in applications such as storefronts due to economies of scale.

While the demand for unitization is continuing to grow, it’s unlikely that these systems will completely replace stick-built systems. However, advances in software and other technologies are allowing unitization to be used in increasingly complex designs. This is a trend major contractor glaziers don’t see going away any time soon.

Jordan Scott is an assistant editor for USGlass magazine. She can be reached at

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