Zinc roofing on the newly-refurbished butterfly shelters at Hunstanton is to be replaced following rapid discolouration.
The manufacturer has acknowledged the materials used were defective and will be undertaking the replacement work at no cost to the council and under warranty, West Norfolk Council confirmed this week.
Replacement work is expected to start on Monday and the shelters will be closed until it has been completed.
Elizabeth Nockolds, borough council cabinet member for culture, heritage and health, said: “This is a Heritage Lottery fundedproject and it is vital that it is up to standard and will last for years to come.
“I’m pleased that we picked up the problem while still under warranty so that the matter can be dealt with as quickly as possible with no cost to tax payers.
“It is unfortunate that we will have to close the shelters while the work is done, but they will be re-opened as soon as possible.”
The shelters were revamped as part of the town’s Heritage Gardens project, which attracted a £1.3m Heritage Lottery Fund grant in 2016.