Cracking on the pillars was spotted by a member of the public, who told Mayor Tania Gibson, prompting a check by council engineering staff.
The Town Square was closed immediately and by late Friday afternoon about a dozen people were on site as the canopy was propped up.
"We have engaged an independent structural engineer (Stantech) to assess the structure and what has occurred. Once the assessment is completed we will know exactly what the issue is and be able to determine next steps," the Grey District Council said in a statement this morning.
Five years ago, soon after the structure was opened, Mrs Gibson (then a councillor) raised concerns about its structural integrity, but today she was diplomatic about its closure.
Staff were reassessing the square's closure and hoped to reopen it later this week.
Work on the Town Square began in early 2017, but struck problems only a month into construction when contractors found poisonous historic coal tarsealing material during excavations.
The $1.7 million bill ended up closer to $2 million.
The council said at the time the steelwork alone for the canopy cost $175,000.
Mrs Gibson dropped a bombshell at a March 2018 council meeting when she said she had been told there was too much "flex" in the framework to safely hold the heavy plate glass it was designed for.
"Dave McMillan (of Dispatch) said it was the worst design he had seen for 40 years," Cr Gibson said at the time.
"Opus (designers) have a lot to answer for. The structure is not braced, and (it) rocks."
The Christchurch-based engineers behind the canopy design had not come to Greymouth to see the problem, she claimed at the time.
"The Opus staff here who saw it were shocked at the way it rocked," Cr Gibson said.
Then-chief executive Paul Pretorius said the council had written to Opus with questions about the design competency and had sought a meeting.
In 2018 he said concerns about the design and its safety aspect had been taken seriously and the structure had been signed off by a professional engineer.
The consultant responded that: "Perception of movement being 'too much' is subjective, and the design deflections were within code guidance prior to any additional measures being added.
"We do note however, that the structure by nature of its design will move a little in strong winds, and this is an expected and accommodated aspect of the design being a lightweight cantilever structure."
In 2020, the Town Square won accolades at the Canterbury Architecture Awards.
The awards jury said the revitalisation of the Greymouth central business district had created a "much-needed, high quality public venue" suitable for a wide range of events.
Opus, now known as WSP, said today it was in contact with the council regarding the structural issues that had been identified
