The Cathedral of the Blessed Sacrament in Christchurch will be demolished.

The Category 1 Heritage building, built in 1905, was badly damaged in the 2011 earthquake.

Bishop Paul Martin informed parishes yesterday, saying the church was unable to meet a 12 point test when it came to costs and safety.

A preference, by former Bishop Barry Jones, to save the nave of the church would cost more than $90 million while full restoration would cost almost $150 million.

The Diocese had set aside $30 million from its insurance payout

No time frame has been set down for demolition - the church is still looking at new sites - and then they can look at design.

Central Christchurch councillor Deon Swiggs says it's sad news for such a grand building, but he believes most will accept the decision.

"The feedback that I;ve had initially is that people are sad, but we're looking forward and hoping that the something else that replaces it will be significant in its own right."