A restriction on the number of windows in one of the external walls because of fire safety concerns meant internal atriums had to be included to ensure acceptable levels of natural light inside the building.
That had pushed out the overall size of the building and pushed up the expected cost, two reports to yesterday's university council meeting said.
The university had already announced plans to spend about $45 million building on a 13,400sq m L-shaped building immediately to the west of the stadium to house several stand-alone activities including Student Health, the Unipol gymnasium and the foundation studies department, and possibly child-care facilities, research spaces and a cafe.
Another $5.6 million is being spent on the land beneath the building.
A two-stage construction project was being considered, with the building adjoining the west wall of the stadium going up first and the rest being left until after the Rugby World Cup in October 2011.
The university's design team had worked hard to produce, in just four weeks, a "well-considered" concept for the stadium building which met the university's needs and the constraints of the site, property services director Barry MacKay said in his report.
However, he said the design was being re-evaluated by the project team to see if the size and cost could be reduced. That process was expected to take two to three weeks.
In a second report, financial services director Grant McKenzie said the concept design was "well over budget" and work was under way to reduce the cost.
As long as university approval for the scheme is given before Christmas and there were no further issues, the building should be completed in time for the World Cup, Mr McKenzie said.
No-one from the university was available yesterday to comment on the details of the concept plan, the increased size of the building, the increased cost, whether any of the proposed facilities might have to be eliminated from the amended design, or whether the building would still be built in two stages.
