Abnormal soil moisture conditions have moved the former convent 30 centimetres south, causing wall and ceiling cracking inside and outside the building.

An engineering company has called for St Michael and St John's Catholic Church to immediately implement measures to ensure the structural integrity of the primary school building.

Connell Wagner structurally inspected the school in March and recommended the parish replace the building with a new purpose-built centre designed for the soil conditions.

Parish council and parish financial group will make a decision on Thursday night.

Father Peter Sherman assured the community that the parish was not looking for the cheapest option but the best outcome in the situation.

Five St Michael and St John's Primary School classrooms, a library, administration, staff room and amenities are in St Brigidine House.

Father Sherman said the school and parish had canvassed information in the Catholic community.

"The main response is sadness," he said.

"It's been an icon in the Catholic community."

The engineer's report estimated repair of the convent's footing system would cost more than $250,000.

The report said that beyond footing repairs, ongoing maintenance was needed to maintain the building's structural integrity.

Principal Brett Anderson said the school was safe.

He said no engineers had given the school a time frame for when the building would be a risk to occupants' safety.

The school has spent more than $50,000 on maintaining the building, including reinforcing the school library.