A potentially dangerous concrete has been found in the gym at Castlehead High School in Paisley, it can be revealed.

Reinforced autoclaved aerated concrete (RAAC) – a lightweight material that can be susceptible to failure when exposed to moisture – has been discovered at the Camphill facility.

It comes little more than a month after Renfrewshire Council said none of its schools or early learning and childcare centres were found to contain this particular form of concrete.

However, questions have now been directed at the local authority after follow-up inspections, conducted on October 16 and October 19, identified RAAC had been used in the construction of the roof of the school gym.

As a result, the council has taken the decision to close the gym for immediate remedial works, which are expected to take months.

Councillor Kenny MacLaren, who represents Paisley Northwest, said: “How worthwhile were the assurances given to us when we were told there was no problem with RAAC in schools?

“I don’t remember them saying it was just an initial survey and there would be further work.

“Councillor Will Mylet and myself contacted the chief executive when the original assessment was made as councillors were informed after parents and press – this time they’ve informed us first to help answer any questions.

“The main issue is the safety of the pupils and school staff. If there was to have been further work done, it should have been made public and precautions taken for the safety of pupils and staff.

“Yet again we’re at the position of officers not fully telling us as elected members what is happening.”

RAAC is less durable than traditional concrete and was used in the construction of some public buildings between the 1950s and 1990s.

Elected members were made aware of the development at Castlehead High in an email from the head of marketing and communications on Tuesday.

The correspondence said: “Initial analysis of available data confirmed there were no RAAC materials known to have been used in the construction of the main school building at Castlehead High School.

“However, during our follow-up inspections on October 16 and October 19, we identified the presence of RAAC limited to the school gym.

“The inspection concluded our analysis of the construction materials of the main school building was correct, but that different material – RAAC – had been used in the construction of the gym hall roof.

“Structural engineers have advised there are no concerns about the current condition of the gym roof structure and it has also been confirmed there is no further RAAC present at the school.

“The school is safe for pupils and school staff, however, we have taken the decision to close the gym and immediately instruct remedial works.

“It is anticipated this will take a number of months to complete … The school will be confirming alternative arrangements for PE as soon as possible.”

Further inspections of gym hall roofs were scheduled to take place at Johnstone High School, Gryffe High School, Trinity High School, Paisley Grammar School and Renfrew High School on Wednesday.

A second phase of primary school inspections is also underway.

A council spokesperson said: “The discovery of reinforced autoclaved aerated concrete (RAAC) at the gym hall at Castlehead High and the decision to close the gym and instruct remedial works was shared with elected members, school parents and carers yesterday.

“This update confirmed the school is safe for pupils and school staff, with no RAAC in the main school building and structural engineers have advised there are no concerns about the current condition of the gym roof structure.

“The remedial works will take a number of months and we will provide an update on the timeline as quickly as possible. The school will confirm alternative arrangements for PE with parents and carers.

“Based on the discovery at Castlehead High and as a precautionary measure, we are carrying out further checks of some secondary and some primary school gym hall roofs.

“All these ongoing checks are informed by the assessments and inspections already undertaken and we will share the outcome of this work with elected members, parents and carers and school staff as quickly as possible.”