A team of 60 building inspectors has fanned out across Christchurch's devastated eastern suburbs to inspect homes in the area.
It is expected that many of those homes will be given a red sticker, which means occupiers will not be able to live there.
Christchurch City Council says Operation East, to inspect more than 300 homes in the eastern suburbs is going well.
The city's civil defence controller, Michael Aitken, says he does not know how many homes are uninhabitable right now or how many people are affected.
Mr Aitken says those issued with a red sticker are being asked to liase with the council's welfare help desk whose staff will offer assistance with moving furniture and finding other accommodation.
Mr Aitken expects many of the families will stay with friends and relatives.
And Christchurch Mayor Bob Parker says the cordon in the central city will be lifted at 5am on Friday unless something significant happens between now and then.
Mr Parker told a briefing at Civil Defence headquarters on Thursday afternoon that many of the earthquake recovery workers are tired, but their efforts are going to plan.
Meanwhile, nearly 400 homes in Kaiapoi and the Pines Beach/Kairaki area are now considered so unsafe that people either have to leave altogether or stay in them only if necessary.
Those homes represent about a quarter of the 2500 residential properties so far assessed for structural or sanitary problems. Ninety-seven of the affected homes have been given red stickers. Another 274 sustained less serious damage.
Fifty-five commercial premises have also been affected.
Waimakariri district Mayor Ron Keating says 15 teams of building inspectors have been working long hours in the area since the day after the quake.
Mr Keating says there may be several buildings in the centre of the town of Kaiapoi that need to be demolished in the next few days.
He says Saturday's earthquake has damaged parts of the sewage system so badly that some residents may be waiting a year before it can be replaced.
Mr Keating says waste water services have been restored to 70% of homes in the town of Kaiapoi, and the remaining 30% will be repaired during coming weeks. That mainly affects properties between the Waimakariri River and nearby Beach Road. Mr Keating says 200 portable toilets have been brought in.
Waimakariri District Council is having to pump raw sewage into rivers and waterways because of damage to pipes and pumping stations. Council utilities manager Gary Boot says it is likely to take weeks to clear blockages and repair pipes to the remaining 30% of homes.
Tap water has been restored to 90% of users in Kaiapoi, but people should still boil it for three minutes, he says.
That advice has also been issued to residents of Pines Beach and Kairaki.
The state of emergency imposed in Waimakariri district has been extended for another week. The district council says the move brings it into line with Christchurch city, where a state of emergency was extended on Wednesday for seven days.