Work to reinforce the roof of the gym halls at Castlehead High School in Paisley after the discovery of potentially dangerous concrete is expected to last until the end of September.

Reinforced autoclaved aerated concrete (RAAC) – a lightweight material that can be susceptible to failure when exposed to moisture – was identified at the Camphill facility in October.

A contract for strengthening works – worth in excess of £800,000 – was given the green light by Renfrewshire Council’s finance, resources and customer services policy board in April. The contractor is due to start on Monday, June 3.

Councillor Kenny MacLaren, an SNP representative for Paisley Northwest, said: “Although it’s disappointing that the work won’t be completed before the end of the summer holidays, it’s important to put pupils’ safety first.”

An update issued to elected members on Tuesday confirmed the project is expected to be ongoing for a number of months.

Chris Dalrymple, the council’s head of facilities and property services, told councillors in an email: “As you know, some reinforced autoclaved aerated concrete (RAAC) was found in part of the building last year.

“While the building remains safe, the gym halls/fitness suite were closed as a precaution while our property services team investigated solutions.

“The agreed programme of work will see new steel beams installed above all four gym halls to strengthen the structure and improve the condition.

“A contractor has now been appointed for this work, they are due to start next week on Monday June 3 – and the work is expected to last until the end of September.

“This is and will remain a very challenging project to deliver.

“We had initially hoped to have the work complete before the end of the summer holidays, but due to the complexity, this will not be possible.”

Meanwhile, interim arrangements for pupils’ physical education, which have involved travelling to the Lagoon Leisure Centre, will remain in place until the work is complete.