Dundee City Council is facing a £4.4m bill to repair hundreds of roofs which were fitted incorrectly.
A total of 450 new roofs should have been made more durable against strong winds, but an error meant out-of-date building regulations were followed during works between 2015 and 2019.
The local authority first became aware of the issue two years ago when a resident’s complaint led to hundreds of other properties being checked.
But the issue has only just come to light ahead of a council meeting on Monday and, if approved, will see the administration fund a multi-million pound, two-and-a-half year repair programme.
Dundee council leader John Alexander admitted the authority had been aware of changes to building regulations in 2015, but that they not had been applied during works.
He said: “We’ll be looking to square that [the cost] off within the overall quantum of the council’s budget, and bearing in mind the broad shoulders of the city, with a budget in excess of £350m, we’ll accommodate it within that.
“But it isn’t acceptable, it isn’t right and it shouldn’t have happened in the first place.”
The authority will now launch an investigation into the error, and opposition councillors said there were serious questions to answer.
“These roofs have been tiled since 2015 and it’s taken an awful long time for this to be noticed,” said Liberal Democrat councillor Fraser Macpherson.
“It has to be rectified, but the question I think all councillors will be asking is ‘why did this drag on for so long?’.”