Cost-blowouts to a proposed $39.5 million performing arts centre at Christ Church Grammar School has caused the elite private school to make some revisions to the original plan.

The lavish three-storey centre, called PERFORM, will be facing some scaled-back revisions after it was found that the projects costs were “significantly over budget” following approval in August last year.

The amended plans were brought back for council approval on Tuesday night.

Under the updated design, the overall height and bulk of the building have been reduced, while elements of the upper level have been scaled back to create a less imposing structure.

The building has also been shifted slightly west to improve separation from nearby heritage-listed structures, including Parry House, and the size of a southern balcony has been cut to increase its setback from the Swan River foreshore.

Concept images from inside the $39.2 million performing arts centre proposal. Camera IconConcept images from inside the $39.2 million performing arts centre proposal. Credit: Supplied

Council officers said the changes resulted in a “less complex design” that would reduce visual impact while maintaining the same function and capacity as the original proposal.

This includes the 470-seat auditorium, a 220-seat black box theatre with retractable seating, an ensemble room, an orchestral rehearsal room and a terrace, all with sweeping river views.

The decision clears the way for the school to proceed with the refined version of the project.