4 days ago
More than braces needed for restoration
Restoration of a prominent civic heritage building in Dunedin has begun. Reporter Grant Miller takes a look behind the scaffolding.
The Municipal Chambers in Dunedin evidently needs some dental work.
Certainly, there is decay.
Parts of the exterior could do with a clean.
Restorative treatment is needed.
Whitening would not go amiss, although too much would create the wrong effect.
The Dunedin City Council invited the Otago Daily Times on a tour around the outside of the building last week. This included climbing up and down scaffolding and taking a close-up look at some of the building's exterior features while council property project manager Mike Restall and Naylor Love projects and interiors manager Paul Stevenson explained what was going on.
The building is listed by Heritage New Zealand Pouhere Taonga as a category 1 historic place.
It still has much of its original detailing.
Mr Restall said work there needed to be sympathetic to a heritage building.
"It won't be shiny white," he said.
The Municipal Chambers in the Octagon opened in 1880 and this was followed by the Concert Chamber, now known as the Glenroy Auditorium, and Town Hall opening in 1930. Together, they are known as the Dunedin Centre.
The council says the entire building complex is showing signs of deterioration and age, and it is in need of care and attention to restore the facade and decorative features.
Pieces of Oamaru stone facade fell from the Municipal Chambers in October 2020, leading to protective measures being put in place for pedestrians. There have since been further occasions where stone, slate and cast-iron balustrading have fallen.
A report for councillors last month said Oamaru stone had relatively low compressive strength and the softness of the stone left it vulnerable to erosion because of weathering and exposure to contaminants.
Parts of the exterior facade have been renewed over time.
"However, the exterior is now at a stage where a more wholesale restoration is required," the report said.
A seven-stage exterior heritage restoration project is under way.
The first and second stages are focused on the Municipal Chambers and later stages will deal with the Town Hall.
A final quote for the first stage was confirmed at $2.7million, including contingency of 10%.
"Much of the work involved is highly specialised, including the preparation and installation of lead flashings, roofing slate and stone masonry," the report said.
The project benefited from expertise developed during restoration work at the Dunedin Railway Station, the council said.
Mr Restall showed the ODT exterior decorative features that had darkened in colour significantly over time. Contaminants were stuck behind a sealant and moisture would be trapped, he said.
The council report he co-authored with property services group manager Anna Nilsen, who was also on the tour, expanded on the point.
"Historically, it was believed that applying a sealant to the surface of the Oamaru stone was the most effective means of protecting it. While this approach was a common practice for the time, the types of sealants used did not allow the stone to breathe."
Around the corner was a series of small blocks described as "dentals". This may or may not be the technical term for them, but a line of white new blocks had evidently replaced blackened "teeth" that were beyond repair.
It also looked like efforts had been made to create what might be termed fillings. Trials were being run to assess the suitability of stone, the ODT was told.
Balusters appeared to be relatively new.
In 1989, redevelopment of the Municipal Chambers included reconstruction of the clock tower in its original form, using reinforced concrete. A report by consultancy WSP that referred to this refurbishment noted many embellishments — balusters and cornices — were replaced with concrete replicas.
Ms Nilsen said two balusters were removed recently to see how they were repaired during refurbishments over the years.
"The majority that were replaced during the 1989 refurbishment have cracked and are in poor condition, owing to the steel rods fixed through the balusters corroding and expanding over time," she said.
Balusters refurbished more recently, in 2010, were fixed with stainless steel dowels and had not corroded.
Ms Nilsen said 31 of the total 87 balusters were in fairly good condition and could need minor repairs only.
Parts of the chambers building wall have a design resembling fish scales. Mr Stevenson said the slates were at the end of their life. They needed to be replaced and the new material had to be cut into the right shape, he said.
The council is also assessing to what extent seismic strengthening might be needed at the property. WSP said the Municipal Chambers had several significant structural deficiencies.
A report about options for seismic strengthening is expected to come before councillors early next year.
Any strengthening of the interior should dovetail fine with the exterior restoration work, the council says.
The overall exterior restoration project, including for the Town Hall, is expected to continue until at least 2028.
