The Dunedin City Council is facing a $60,000 bill to
strengthen the Wall Street shopping mall's glass ceiling and
protect against further spontaneous glass explosions.
It has also emerged other Dunedin building owners could face
similar bills for buildings constructed before regulations
were toughened two years ago.
The concern comes after two men - one in a wheelchair -
escaped injury despite being showered with falling glass
fragments when a ceiling panel spontaneously shattered inside
the Wall Street mall in April.
The incident prompted an Australian construction industry
source - visiting Dunedin when the mishap occurred - to warn
the glass needed strengthening to prevent a possible repeat,
which could have fatal consequences.
Council city property assistant manager Rhonda Abercrombie
said this week the incident had prompted the council to pay
for a protective film to be added under every glass ceiling
pane in the shopping mall.
The film would prevent fragments falling if another piece of
glass shattered, she said. Work began last month and was due
to be completed next week.
The retrofit would cost about $60,000 and be paid for from an
operational maintenance budget for Wall Street, she said.
Council staff had been advised a repeat was "very, very
unlikely", but had decided to be "incredibly proactive", she
"There's no design flaw. The council didn't have to do it,
but we made the call ... that we would take this
Parker Warburton Team Architects Ltd was the lead architect
behind the $34 million, council-owned shopping mall, which
opened in March 2009.
Parker Warburton director Simon Parker said yesterday the
mall was designed to meet the regulations of the day, but
glazing codes had been toughened in 2010.
That meant the mall - and possibly other buildings in Dunedin
- would need to be retrofitted if owners wanted to bring them
up to the newer requirements.
"There's the potential for any building that was built prior
to 2010 ... [to] also have this issue.
"There's certainly projects which were designed to the
standard before it was upgraded which would be in the same
April's incident was blamed on nickel sulphide inclusion,
which could occur during the manufacture of float glass that
was later toughened.
Nickel contamination meant nickel sulphide crystals, formed
during glass toughening, slowly reverted to a larger form and
expanded to trigger shattering.
The phenomenon was a "worldwide problem" that could affect
one in 2500 sheets of glass, but 90% of those shattered
before leaving the factory, Mr Parker said in April.
Australia had already adopted new regulations requiring
toughened glass to be heat-soaked - causing faulty toughened
sheets to fracture - and laminated before use.
Yesterday, Mr Parker said New Zealand had since adopted its
own new rules partly in response to incidents such as that
which had occurred in Wall Street and other buildings.
"There is certainly retrofitting ... going on throughout
The film was being added underneath all 201 panes of glass
inside Wall Street, and attached to the edge of each ceiling
frame using structural silicone.
"In the event there is ever another breakage, the film just
really holds all the glass, and then the film itself is
attached to the edge of the frame, so it doesn't fall in.
"It's clear, so you'd never ever even know it was there."