Two Christchurch youths sleeping in an abandoned inner city building. The multi-storey building is home to about eight people aged between 16-27.

The flame from Luke's cigarette lighter flickers down the maze of dark corridors of an earthquake abandoned inner city Christchurch building.

It is pitch black.

The lighter casts a soft, ethereal glow against the walls.

The ground cannot be seen but squelches under foot.

Mould, wet carpets and unwashed bodies overpower the senses.

Eight people from ages 16 to 27 live in the maze of bedrooms of the multi-storey building. There is no plumbing or working toilets.

Luke, 23, has been in six abandoned buildings since January.

"They get knocked down, or get rolled [by police] or are unlivable," he said.

Luke has depression and anxiety. He self-medicates with synthetic cannabis.

In summer, Luke and about five others huddled in a lean-to, with two couches as a place to sleep. They made it because "technically" it is not an abandoned building so they could not be arrested for being in it.

But it is too cold in winter to stay outside.

Lily, 23, lives in one of the bedrooms. She had a baby three months ago. Her "beautiful" newborn girl is with an aunty. It was agreed to before the child was born.

"I used to be embarrassed of living like this. I thought this kind of stuff only happened in the movies," she said.

She has post-natal depression and thinks of suicide often.

"There is nothing I can do about it out here. I feel like the filthiest, dirtiest person ever," she said.

It is always cold.

She has been in the building for a month. At night she is a sex worker on Manchester St.

"I tried to get a benefit but it is kinda hard going to appointments when you don't get the mail. Then you have to tell everyone you are homeless in order to get it," she said.

"You try and apply for jobs but you don't have a qualification, and well, how do you describe where you live?"

298 Youth Health Centre director Dr Sue Bagshaw said youth homelessness is worse post-earthquake.

"There is no low-cost rental properties, which is why they [youth] are living on the streets. If you are on a youth benefit you get $120 a week maximum.," she said.

Presbyterian Support upper South Island manager youth service Heather Batin, said about 23, 16-19 year-olds in Christchurch were classed with "no fixed abode".

Using data from youth benefits, she said about 63 in substandard housing including couch surfing.

"It is an absolutely chronic situation for young people. It is worse for them because they are always at the bottom of the list for rentals and board due to their age," she said.

Bagshaw said: "Eighty per cent of mental illness starts in this age group, they need support. What we are doing at the moment is nothing. It's crisis point in Christchurch."

Christchurch city councillor Glenn Livingstone said its social housing policy could be extended to include youth.

Meanwhile, back at the abandoned building, Luke is scouting around to see if anyone will see them slip inside. If they are seen, they will be arrested and be back to sleeping outside until they find another building.

Lily has gone out to work.

"I buy their drugs and food so they are not grumpy, so they don't do commit crime. We are all in the same boat. We all have nowhere to live, we are all hungry, we are all grumpy, we all need food. We only have each other."

* Real names have not been used because it is illegal to squat in buildings.