Renovating while holding on to history with Nord-Lock X-series washers

The Malmö Börshus building is an icon in Sweden’s southernmost city. Located next to Malmö Central Station, its sandstone facade and rows of massive windows evoke a sense of both the historic and the modern. Inside, an internal courtyard with vintage marble floor sits under a geodesic-like roof of skylights. It’s an eye-catching feature at the heart of the landmark, aligned to contemporary standards without sacrificing the building’s heritage.

Since first opening its doors in 1879, Malmö Börshus has been an architectural fixture in three separate centuries. Today, the building houses floors of modern offices, conference and meeting areas, as well as restaurant and event spaces. It reopened in early 2026 after a thorough renovation that began in 2023 with a focus on flexible functionality in harmony with the building’s cultural and architectural character.

A core element of the renovation was transforming the central courtyard into a light-filled atrium with a futuristic skylight roof using German window maker Schüco’s cutting-edge Grid2Shell system of self-supporting aluminum geometric frames for glass structures.

In a video documenting the roof’s installation in the summer of 2025, Peter Stockbrügger, a Senior Manager at Schüco, highlights the project as a first-of-its-kind application for Grid2Shell as a skylight.

“This construction, this building is exciting for us,” says Stockbrügger, adding later: “It's great to be a part of such a story so that we can bring new life to an old site.”

And the Nord-Lock X-series washers are part of the Grid2Shell skylight roof at Malmö Börshus but also part of the story of how it came to life.

“They were really open-minded and interested in improving their existing solution”

Founded in 1951 and based in Bielefeld, Germany, Schüco produces windows, doors, facades, and other building elements. Its products are used all over the world, but it’s as big a name as it gets for windows in Europe’s building sector.

Grid2Shell is one of Schüco's newest products. An aluminum-and-glass modular system for building enclosures and architectural elements, it uses a plug-and-play design with polygonal or triangular units to enable freeform construction without load-bearing substructures.

But Schüco engineers wanted to improve the system’s bolting, ensuring it was protected as much as possible from unintentional loosening.

“They were using stainless steel bolts with aluminum, which is okay for material pairing, but they were concerned about any kind of vibrations, dynamic movements of the Grid2Shell structure,” says Frank Götz, Nord-Lock’s Global Business Development Manager for Buildings and Infrastructure.

Furthermore, different metals react to temperature changes differently, increasing the potential for slackening in bolted joints.

“Just a 10 or 20 degrees change, plus or minus, and the components will behave differently due to the material properties,” Götz explains. “You may have a small gap or deflection that’s not possible to avoid.”

Schüco connected with Götz about potentially replacing some of Grid2Shell’s bolting elements with a Nord-Lock product line at a conference sometime in 2023. The X-series washers seemed ideally suited to the task. But it took more than a year and a half of working together to confirm that, as well as find the optimal sizing and material specifications through testing, analysis, and review.

“They were really open-minded and interested in improving their existing solution,” says Götz, who notes that Schüco went further than most other customers. “They also did tests with external laboratories and hired some outside experts as well. And then they decided to go for it.”

The updated Grid2Shell system featuring Nord-Lock X-series officially debuted at the Bau trade fair in Munich and, a short time later, was used for the Malmö Börshus project.

A dual-function design ideal for the construction sector

The Nord-Lock X-series washer features wedge-locking technology to keep bolted joints from loosening and prevent unintentional rotation once tightened. Its conical shape also acts like a spring mechanism, maintaining the joint’s clamp load and counterbalancing any settlement or relaxation.

That dual-function design makes the washers perfect for building and construction applications like Grid2Shell.

As Stockbrügger explains in the Malmö Börshus construction video, “We are working with two materials, a steel bolt and aluminum profiles and nodes, and the difference in thermal expansion can be compensated by the Nord-Lock X-series washers perfectly.”

Although the Nord-Lock X-series washers have been on the market since 2012, they’re just now gaining ground in the construction and building sector. That’s largely because Nord-Lock X-series washers recently qualified for the CE marking in 2025, meeting the EU’s strict standards for construction use.

In fact, one of the first construction projects to use CE-marked Nord-Lock X-series washers was the Grid2Shell skylight roof for the Malmö Börshus renovation. As Götz explains, it’s a significant detail.

“The CE marking demonstrates that the Nord-Lock X-series washer is an effective, proven, compliant securing element,” he says. “And it was an additional element that improved the level of safety and confidence in the structure”