Bending Over Backwards

From One Continent to Another, Silicone Glazing Projects take Shape

Back in December 2012, WilkinsonEyre, a London architectural firm, entered a global competition to design a landmark Australian building. The firm was one of four contestants placed on the shortlist to design a skyscraper, Crown Towers Sydney at One Barangaroo, along the Australian Harbour. Five months after entering, WilkinsonEyre received the news they would design Sydney’s newest landmark structure.

After more than seven years of international collaboration, consulting and work, the tower was finally completed in December 2020.

The structure stands about 900 feet tall, with 71 floors and three different façade types. One of the most eye-catching parts of the façade’s design is its subtle twist with each level, almost as if it was a piece of PlayDoh, stretched and twisted into a cylindrical shape.

The glass on the hotel portion, the shorter section of the structure, is fairly simple and relatively standard, says Conor Worth, an associate at WilkinsonEyre.

“On the main tower, however, there are two separate types. It’s when the geometry is quite a bit more curved … the front of the tower is rectangular wall paneling. But it’s on a staggered setup.”

What Worth refers to as the back of the building consists of the most intricate phases of design.

The back faces west and is where the geometry is the most extreme, said Worth. In order to achieve the twisted shape the structure was intended to have, the flat panels used for the hotel portion couldn’t be utilized.

“We had to end up going for a triangulated scheme.”

Triangle-shaped panels would end up adding more to the structure than one would anticipate. Thanks, that is, to the sunny Australian weather.

“As the sun moves around … the light really hits each panel individually and it sparkles year-round because of that grid,” said Worth.

The complexities of the façade were accomplished with the help of China-based glass supplier Xinyi Glass, South Korean contracting group Iljin Unisco and global silicone and sealant provider Dow Performance Silicones.

Dow was contracted by Iljin. The South Korean group selected “DOWSIL as their silicone sealant for the structural glazing applications, the insulated glazing secondary sealant application, and weatherproofing application for the project,” says Jayrold Bautista, associate TS&D scientist based in Singapore at Dow Performance Silicones and the leader of technical services for the structure.

The tower’s unconventional form was accomplished largely due to the façade being made up of cold-bent glass—the glass is manufactured flat, then on-site, corners are bent and pulled into place.

However, installation of cold-bent glass is easier said than done.

“There was a concern from the contractor regarding whether our solutions, especially the structural sealant and the IG secondary sealant, can withstand the cold bending of the facades,” says Bautista. “This is not an easy ‘stroke of a pen’ approval where in one sitting, you can look at the contractor’s drawing and say that our solutions can work. Dow’s global expertise was tapped because we have previously worked with cold-bent panel projects. It was also timely as we were already advancing our previous guidelines for such designs to enable greater design flexibility. The contractor was also not used to such design so it was essential to explain to them the risks of such design but at the same time ensure them that we are confident of our solution as it is based on both engineering and previous project scenarios.”

The Crown Towers Sydney was an international collaboration from conception to completion. While WilkinsonEyre is located in London and the jobsite is in Sydney, Dow and Iljin also had to be concerned with global travel.

Another challenge, according to Bautista, was the contractor’s locations, as their design team was in the Philippines. “Their façade fabrication was in South Korea. And the project was in Australia. So three locations [needed] to be coordinated.”

The Crown Towers is more than just its façade and complicated curtainwall. It could be hailed as the ultimate group project. After years of work, competitions, travel and even a pandemic, several countries and people were all tied together and connected at One Barangaroo, the Crown Towers in Sydney.

Lourdes (Luly) Hernandez is the assistant editor for USGlass. Email her at lhernandez@glass.com and connect with her on LinkedIn.

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