Hutt City Council is telling owners of earthquake-prone buildings to carry out strengthening work soon - or the council will do it for them and recover the cost.
The council has identified 25 properties that need work. About half of them are in Petone and are heritage buildings.
Mayor Ray Wallace says some owners have known for 12 years that strengthening is needed. If nothing is done soon, he says the buildings could be fenced off and the owners prosecuted.
The council's own headquarters in Lower Hutt, which only just meets the safety threshold, may also have to be pulled down.
The council is also looking at passing a by-law that would double the safety threshold for heritage buildings.