A Christchurch city councillor is threatening to chain himself to the cathedral to prevent demolition.

Cr Aaron Keown said today the cathedral would be demolished ''over my dead body''.

''I would be in there chaining myself to the building to stop that and I know lots of other volunteers would come in to do that.

"Forget Lucy Lawless' little eight-person campaign, this would be a big one,'' he said.

''We'd form a ring around the building and not let them in. It shouldn't even be a discussion.''

Cr Keown said he had been inside the cathedral after the December 23 quake and it was in ''good shape''.

The damaged west side was ruined but could be replaced with glass and the steeple rebuilt with wood.

Only four tiles on the roof had loosened, he said. ''If the building was in trouble, the roof would look like New Brighton beach. It would be all warped, the tiles popped and beams gone.''

Cr Keown likened it to a person ''busting their leg'' and the doctor telling the family, ''right, we're going to have to pull the pin now''.

''I don't mind making new history but not when it's not necessary. We're going to build enough new history,'' he said.