Among them was a green roof planted with sedum to support biodiversity.
In July 2021, the school's first floor was temporarily closed after it was discovered roof repairs were needed.
Work to replace the roof began in April 2022 and wasn't completed until January 2023. To fund the £2.6m work, money was released from council's reserves.
On December 12, an Extraordinary Meeting of the council was held to discuss potential legal avenues as the council sought to recover the cost of replacing the failed sedum roof.
As this was held behind closed doors, details of a report presented to councillors have not been disclosed.
The local authority said specialist external solicitors were appointed to advise the council on its chances of recovering the £2.6m. Independent expert evidence was also commissioned but this "did not adequately support the council's case".
As a result, Anglesey Council was advised not to issue court proceedings as an unsuccessful challenge would "risk significant legal fees". Dylan J Williams, the council's chief executive, s...