In a development that helped breathe new life to an old building, the project team used a light-gauge framing system made from TRUECORE steel to add 8 new levels to a 50-year-old 12-storey building located at 388 Lonsdale Street in Melbourne.

Built by Verve Construction based on the design by Urban Design Architects for the client, Aurumstone, the project had several challenges including the existing structure’s ability to bear the additional load; the age of the building, which meant that the grid could have been anywhere between 10mm to 30mm off, requiring the new steel structure to accurately meet the existing columns; and the lack of external access to build and clad the walls, which required all the new levels to be built without scaffolding.

Peter Blythe, managing director of steel fabricator Dynamic Steel Frame, explained the key elements of the build:

Floor system 

The highly modularised floor system comprised a 2.7-metre wide by 5.5-metre long fully finished floor cassette, framed by 1mm gauge lightweight TRUECORE steel. Each flooring cassette had four lifting points, which were craned into position and dropped on top of the structural steel of the portal frame composed mostly of 200mm universal beams. The cassette was fixed in with screws and ready to walk on.

Wall façades

The wall façades comprised a system of interlocking panels made from COLORBOND steel in the colour Monument, and COLORBOND Metallic steel in the colours Celestian and Rhea that finish a frame of insulation and plasterboard internally. Built off-site, these were simply lifted onto the building by crane, where they were fixed from inside into wall frames made from 1mm gauge lightweight TRUECORE steel framing.

Wall frames

The wall frames allowed for 10-metre long by 3-metre high panels; no heavy structural steel was needed to meet the walls’ engineering requirements.

Carlos Cagliero, senior project manager at Verve Construction explained that 3D modelling ensured the system would work, and allow for a number of mechanical and plumbing services. It also ensured that appropriate joist-deflection requirements were met to prevent noise transmission between floors.

Roger Schmidt, project architect at Urban Design Architects led the design of the project while Irwin Consult provided structural engineering services.

By using lightweight TRUECORE steel framing, the development benefitted from cost and time savings due to the uniformity of the manufactured frames and ease of handling, as well as increased safety from reduced working from height requirements.

Summing up the project, Cagliero said, “It’s very rare. We’re starting at 12 storeys and going up another eight and that creates a lot of logistics to deal with. We worked with Peter and his engineers at Dynamic Steel Frame to push the framing system to its full capabilities and maximise our apartment space and building value.”

Blythe added, “It would be difficult to achieve the number of floors with alternative materials such as concrete due to strength-to-weight ratios. Due to its weight above the existing building if we were to use concrete we would have only been able to go up one or two levels. With our lightweight steel framing made from BlueScope’s TRUECORE steel, the client was able to go far higher than that. They are definitely very happy about it.”

Principal steel products used in the Lonsdale Street project included 1mm gauge lightweight framing made from TRUECORE steel; and structural steel components comprising of 200mm UBs, COLORBOND steel in the colour Monument and COLORBOND Metallic steel in the colours Celestian and Rhea for the walling.