The building sits along York St facing the road. "It tells people what we are about," Mr Cranshaw said.
"It's going to offer more learning space. It's a multi-purpose classroom so it can be used for multi-purpose things." St Augustine's has about 30 boys at the moment with an overall roll (including St Dominic's Girls' College and St Anthony's Primary School) of about 130.
Mr Cranshaw said the idea for the building pre-dated his appointment as principal in 2012 but the design and build process had taken just over a year.
"Everything's been right on track," he said. "The funding came through the bequest of one of our faithful. That allowed the project to go ahead."