International Conservation Services worked with heritage consultants Geoff Ashley and Rebecca Hawcroft of Godden Mackay Logan and structural engineers Simon Wiltshier and Alison Naimo of Hughes Trueman to identify the conservation works required and to agree on appropriate methods for each element. Investigations included:
- assessment of the condition of each column and truss
- scheduling of damage to individual elements of each component
- review of alternative conservation treatments
- investigation of past finishes to the columns and trusses
After completion of these investigations, we carried out the following conservation works on the 27 cast iron columns and 9 cast and wrought iron trusses:
- Blasted the cast-iron columns before painting with a zinc-rich epoxy primer and 2 pack polyurethane topcoat;
- Repaired the three broken columns by pinning the pieces to a new galvanised steel CHS installed inside the columns;
- Undertook various other repairs to the cast iron columns and truss support brackets on the columns, including casting new capital plates;
- Deconstructed the trusses to straighten bent wrought iron angle and flat bar tension members
- Cast new compression strut members to replace broken or missing pieces of the original cast iron compression struts;
- Installed new purlin angle supports to carry a new roof; and
- Blasted and painted the trusses to match the columns.
The introduction of new material was limited to:
- new purlins over the original trusses;
- new steel aisle trusses over three side bays;
- a new crane rail to interpret the early 20th rail; and
- translucent fibreglass roof sheeting and rainwater goods over approximately one third of the structure.
The new material has been introduced to provide for public use, to protect original fabric and to interpret the likely building form. Site signage and a cyclic maintenance plan is currently being prepared.
Hughes Trueman worked closely with the ICS and GML to maximize retention of existing fabric and also assessed the strength of the columns, trusses, brackets and connections and designed the strengthening, structural repairs, connections, bracing and footings necessary for re-erection. Hughes Trueman also provided advice on the new structural elements necessary to re-connect the components, support the cladding and brace the erected structure. The principle structural issues were:
- reconnecting and re-erecting the fractured columns allowing them to remain in the finished structure with broken and missing elements displayed;
- incorporating tolerances in connections to allow site adjustment to fit distorted and irregular elements together;
- achieving fixity and anchorage at column bases to make the structure rigid; and
- connecting new elements to old without the use of welding and minimizing the drilling of original cast iron.
Consultation and Client Needs
The redevelopment of the former ACI site has been staged over a decade and this has included a number of development consents for which heritage impact statements were prepared. The strategic approach for the Grissell building has been to prepare a CMP and archival recordings prior to its careful deconstruction and a detailed reconstruction strategy prior to construction documentation. All stages have included consultation with the City of Sydney.
The project has a very broad audience that includes not only residents and visitors to the major residential complex but also a potentially large international audience interested in industrial structures dating from the Industrial Revolution.
A large public park has been created in the centre of the Meriton development that is partly managed by City of Sydney and partly by the Body Corporate of the Meriton development. The Grissell building is the key visual element and focus in this park area. The structure will allow for informal public use for gatherings and picnics etc. The new roofing structure was designed to facilitate these gatherings. Interpretation will be provided to communicate the significance of the Grissell building to park users.
Australia ICOMOS Burra Charter principles have been followed in assessments, conservation planning and works documentation. Appropriate professionals expertise was engaged in all phases of the project.
Heritage Benefits and Issues