Brisbane is facing a homelessness crisis, the premier warns, amid fears bodies could be lying undiscovered in flood-hit parts of the city.

Premier Anna Bligh convened a special cabinet today to formulate a detailed recovery plan for the flood-devastated state.

She said it was clear many people would be homeless for an extended period of time, and all options, including "work-camp" style hubs were being considered to accommodate them.

Meanwhile, Lord Mayor Campbell Newman has warned there could be bodies lying undiscovered in Brisbane homes.

"We are concerned, sadly, about the potential for people to be found who may have died," he told reporters on Monday, urging people to check homes where there'd been no activity for days.

"We're concerned, as well, that there may be elderly people or other people who have literally had a nervous breakdown. They may be sitting in their homes in a dark room and need help now."

Ms Bligh said Brisbane was facing "a massive relocation task" after 11,900 homes and 2500 businesses were flooded.

She said many flood victims were staying with family and friends while others had insurance policies that would cover the cost of alternative accommodation.

But, she warned: "There will be a very large number of people who might not have any of those options".

"We are currently looking at how we can provide temporary accommodation. It may be necessary in some places to have, effectively, a temporary work-camp set up," she told the ABC.

"We have a large homelessness task ahead of us and we're looking at every option."

The grim search for bodies was continuing today in the devastated Lockyer Valley, west of Brisbane.

The death toll still stands at 18, most in valley communities. Police say grave fears are held for 14 others who remain missing from the Toowoomba/Lockyer Valley area.

Queenslanders are being asked to observe a minute's silence at 2.33pm (4.33pm NZT), exactly a week on from the devastating flash flooding that brought death and destruction to Toowoomba and the nearby Lockyer Valley.

"Wherever you are, please stop for a minute and remember those innocent people who lost their lives simply because they were in the wrong place at the wrong time," said Scott Buchholz, the federal MP for Wright whose electorate covers the valley.

With 51 of the state's 73 council areas affected by flooding, federal treasurer Wayne Swan says the disaster may prove the costliest to ever hit Australia.

"It looks like this is possibly going to be, in economic terms, the largest natural disaster in our history," Mr Swan told the ABC.

"This is very big ... It's not just something which is going to occupy our time for the next few months. It will be a question of years as we go through the rebuilding process ..."

Mr Swan flagged changes to the insurance industry, amid concerns over insurers refusing to compensate people who thought they were covered for flood damage.

"I don't think there's any doubt that there is a need for reform in this area. But, at the moment, we're concentrating on dealing with the practical realities of what people are facing today," he said.

He also warned Australians could expect an increase in the cost of living as a result of the floods, which have hit food bowl regions, including the Lockyer Valley.

As Brisbane gets back on its feet, the premier has suggested some properties in flood-prone areas may not be rebuilt.

"We have some very old homes that are in places that are clearly flood-prone and we're going to have to give some consideration in the rebuilding task to where they should be located," she told the ABC.

"Equally, there are some places that have been approved by various authorities 30 and 40 years ago, that are not so old, and they're going to have big questions as well."

As Brisbane's CBD returned to life on Monday, workers were being urged to use free public transport, car pool, and to stagger their arrivals to ease pressure on damaged road networks.

Mr Newman has said ferry services would remain suspended for at least three months after terminals were severely damaged.

Five CBD buildings remain without power, Energex said.