"All these factors, as well as establishing the status of all insurance claims, need to be known before a comprehensive report can be completed," he said.
While this plan is being considered, work on the Basilica continues.
The Catholic Cathedral, which was completed in 1905, suffered massive damage in the February 22, 2011 earthquake.
The large copper dome which graced the building was painstakingly removed last year as its weight posed a risk to the rest of the structure as it forced weight-bearing structures outwards.
"We are really looking at three options - whether to demolish the existing building, to retain what we can of the Basilica and rebuild to its former glory, or, in the short-term, whether or not to mothball the building until we have a clearer picture.
"Early indications are that the costs of retaining and rebuilding the Basilica are in the vicinity of $100 million. The nave is the only part of the existing building that could be retained, but it will still need extensive reinforcing to bring it up to the required standard."
The board is having costs prepared for the removal of the large organ and also the stained glass windows.
"This is a frustrating time for all, but we must ensure we work wisely. The Cathedral of the Blessed Sacrament is only one piece of the diocesan jigsaw, and until we know all the pieces and the community has been consulted, we are reluctant to move with any haste.
"Getting it right is everyone's first priority," he said.