Nicholson Construction for the Ballarat Town Hall

Specialist Heritage Trade Skills, Publically Owned – Finalist

Owner: Ballaarat Mechanics Institute

Architect/Designer: IJBO & EMTB

Builder/Tradesperson: S.J. Weir (Ballarat) Pty Ltd

Nicholson Construction was engaged by the City of Ballarat to undertake heritage repair works to the façade of the Town Hall of Ballarat in August 2009.

The scope of works generally included:

• The removal of existing and inappropriate acrylic render from the north, east and west elevations, and replacement with traditional render;
• Repair of worn and damaged render features including modillions, bottles, parapets, sills and ledges;
• Removal of worn and damaged stone to the feature pediment and replacement with new hand masoned stonework;
• Replacement of damaged (non-traditional) glass louvers in Bell Tower utilizing traditional materials and workmanship;
• Restoration to the clock face glass and clock face steel numbers and hands;
• Extensive restoration to the existing steel crow’s nest utilising traditional (Blacksmith) materials and workmanship.

The Head Contract required the appointment of specialist traditional subcontract trades including stonemasons, (roman) lime renderers and blacksmiths.

Nicholson Construction was also responsible for providing access on all four facades, which required the erection of numerous substantial scaffolding structures.  That required independent engineering and specialist subcontractors to erect and dismantle.  The scaffolding was particularly challenging for the workers required a safe working place but also an environment that allowed them to work uninhibited by the positive scaffold connections which were required to be fixed adequately to the building face.  The scaffold component required involvement from industry engineers, scaffolding specialists, multiple on site workers, management and government safety bodies (Worksafe) to be completed successfully.

Specialist Trades

(1)   Stonemasons

A major component of the scope required the appointment of a specialist stonemason to carve and replicate the existing feature stonework on the building.  The specialist skills required for the work are not available in Ballarat, and IG Parker (Ian Parker) from Melbourne was engaged to carry out the works.

The first step was to source stone which matched the existing material originally used on the building. The original stone was sourced from Constitution Dock in Hobart and new material from that location is obviously unavailable.  The nearest match for the stone is from Germany, and is called Udelfanger Sandstone.  20m3 of rock was sourced, roar cut into 2m3 blocks and shipped to Melbourne.

The rock was imported by a specialist supplier who shipped the material to Harcourt to be cut into stones of suitable size for the project.  Every piece of feature stonework requires shop drawings to be created and approved by the Heritage Architect Lovell Chen.  Once shop drawings were approved the stone was cut into appropriate sizes and hand carved to match the feature stonework, then delivered to site and installed.

This component of work heavily influenced the timeline of the project dur to the large man hours required to mason the roar material, however the process was streamlined due to experienced of the Heritage Architect Lovell Chen, headed up by Mr Fraser Brown.

(2)   Render

The render component of the works required the removal of an existing acrylic render that has been applied to the facade sometime around the year 2000.  The acrylic render product that had been used was incompatible with the existing brick and stone used in the walls of the Town Hall, and was not allowing the wall to “breath” thereby reducing the serviceable life of the walls.  This material, whilst appearing in good condition, had to be scaled away from the walls, and a traditional sand, lime and cement render using material that matched the existing render, re-applied by specialist Roman Renderers.

A sample of the existing render had been studied under a microscope to identify the materials used in the mix, and it was revealed that much of the material was sourced from old mine mullock heaps – which are unfortunately unavailable to source render from today.

So a number of samples and mixes using different sands, cement and lime were trialled and left to age and weather beside the existing building in order to choose the best matching color and aging characteristics.

Unfortunately, the skills required to remove and replace a traditional (Roman) render are not available in Ballarat on a scale necessary to complete the works on time, and specialist renders from Melbourne (Norvech Property Services Pty Ltd) were engaged to undertake the works to the satisfaction of the heritage architect.

(3)   Blacksmith

The existing original Crow’s Nest at the top of the Town Hall tower was installed in the 1800’s and had suffered from over 100 years of weathering.  It was deemed unsafe, and as a result, access to the Crow’s Nest from the inside of the tower was not available.

The lace work is made from cast iron, and required extensive repair including replacement of missing parts and repair of rusting and weather damaged areas.

These works required the expertise of a traditional blacksmith, familiar with the skills required to work with cast iron (rather than wrought iron) and the entire lace work was removed, delivered to Daylesford to Mr John Madigan, where the repairs were carried out.  The lace work was reinstalled and is now compliant with modern building codes for fall protection.

(4)   Scaffolding

Despite the heritage nature of the works to the facade, the project required an extensive and sophisticated modern day scaffolding structure in order to gain access to the work face.

A scaffold structure was erected in four stages for the works:

• West Facade
• East Facade
• North Facade
• Tower

Each stage required a significant scaffold structure that was designed by a specialist scaffold erection company, and independently certified by a structural engineer. Complication the engineering was the requirement to cover the entire scaffold with shadecloth to provide protection for workers (from the weather) and the public (from falling debris), and hide the unsightly nature of the repairs.  Adding to this, was the need to install direct fixings into the walls of the Town Hall in areas that could be repaired once the scaffold was removed.

The scaffold contained a weather station that continuously measured wind speed, and a system was in place to re-inspect and adjust the scaffold after the wind speed exceeded 50kts (which was quite often!).

The scaffold also had a monitored security system installed to deter youths from climbing the scaffold at night and potentially forcing entry into the Town Hall via upper level windows.

List of Key Personnel on the Project: