88 Walker Street Soffit
Location: North Sydney
Completion Date: January 2023
Size: 420sqm Membrane + 143 Aluminium Panels
Fabric: PTFE & Custom Aluminium
The 88 Walker Street Soffit adds a stunning visual detail to the brand-new high-rise development in North Sydney. The PTFE Mesh and curved aluminium petal soffit crowns the open-air podium section of the building which rises above the historic North Sydney Fire Station.
Created by suspending 420 square metres of PTFE open-weave mesh fabric and 143 custom-designed aluminium panels below the building’s formwork, the 88 Walker Street soffit features integrated lighting to further enhance the stunning visual statement.
The design intent of the 88 Walker Street soffit was to provide an architecturally unique finish to the lower facia of the high-rise development. Created with an aluminium petal array above the outdoor podium area of the new building, the soffit includes an innovative use of a tensile membrane ceiling installed above the open petal arrangement.
Suspended below the rendered concrete base of the building and above the aluminium feature panels, the tensile membrane ceiling was designed was to hide the building formwork, as well as provide a surface to reflect the integrated lighting off, providing a more visually appealing soffit.
The design for secondary steel employs a multi-layer grid structure, suspended from the building’s formwork via steel droppers. Once we had the design of the secondary steel structure locked down, we could proceed with the multitude of small connection details; we designed special steel cleats for the interface of the primary and secondary steel sections, as well as custom steel cleats to connect both the PTFE membrane and aluminium petals.
The architectural specification for the 88 Walker Street soffit project listed PTFE Open Weave Mesh and we proposed Chukoh FGF-412-25 for its superior fire-performance characteristics. The woven fibreglass base cloth is non-combustible, and the PTFE coating is thin enough to achieve a fire performance solution.
The lightweight PTFE open-weave mesh fabric is an ideal façade and soffit material. The long-lifespan and low-maintenance qualities of FGF-412 were vital to the project as the membrane is installed above the aluminium soffit, with limited access for regular maintenance.
Made up of 5 panels, the 420m2 PTFE membrane ceiling was designed to allow for ease of installation. Rather than a sewn rope edge along the straight edges, we employed a loop-style edge detail to connect the membrane directly to secondary steel around the perimeter. Curved rope edges and clamp plates were used to hold the membrane in place around the exposed building support pillars. Fabrication of the PTFE membrane panels occurred in our Brisbane facility and production was timed to coincide with the installation of the secondary steel.
The 143 bespoke aluminium panels required were based on 15 separate designs. The flat aluminium panels were laser cut and then uniformly curved before being powder coated on both top and bottom to protect the alloy. Shipped to site in 5 separate deliveries, the aluminium petals connected to the supporting steel grid using arched steel rib-brackets.