About 35% of medium and large-sized businesses affected by the Queensland floods do not have insurance, a National Australia Bank (NAB) survey has found.

NAB used the framework of its regular monthly and quarterly business surveys to investigate how the floods are affecting business and has found only 8% of firms expect to use insurance as their main source of funding for recovery.

Chief Economist Alan Oster says 90% of the 380 firms surveyed nationally in late January said they had been affected by the floods.

Although he believes there will eventually be a “kick” to the economy as companies rebuild, he says the lack of insurance is likely to mean the economy is weaker than might be expected in the early days.

“Most businesses will rely on cashflow or savings to finance their recovery”, he told insuranceNEWS.com.au.

The floods affected a quarter of Queensland respondents and 10% of businesses nationally.

All the firms employed more than 50 people and Mr Oster says some of those in the mining and construction sector may self-insure.

Just over half said they were back to pre-flood levels within a week and 22% said they would take more than a month to recover.

“Some firms that are struggling will not be able to recover and 1% have said they would not be back in business,” Mr Oster said.