Updated Insurance Council of Australia data on the storms and floods that impacted southeast Queensland and coastal NSW in February and March shows the event set a record to be Australia’s costliest flood ever.

Insured losses are estimated by the ICA at $3.35 billion, based on costs from 196,761 claims across both states, the highest ever for a flood.

More than 11% of the claims, which are made up of 86% property, 13% motor and 0.6% other, have been closed so far, and $580 million paid to policyholders.

Only four other disasters in Australia have cost more in normalised values: The eastern Sydney hailstorm in 1999 ($5.57 billion), Cyclone Tracy in 1974 ($5.04 billion), Cyclone Dinah in 1967 ($4.69 billion) and the Newcastle earthquake in 1989 ($4.24 billion).

ICA data for the 2011 Brisbane floods put the cost of that disaster at $2.38 billion on a normalised loss basis – a way of calculation to give a present-day perspective of historical events.

The rise in insured losses compared to previous floods is being driven by higher costs in personal property, personal contents and commercial property classes, ICA says, reflecting a challenging supply chain environment and a rise in the price of materials.

"In monetary terms it was in fact the biggest (flood) ever,” ICA CEO Andrew Hall said. “It’s imperative that governments commit to a significant increase in investment in programs to lessen the impact of future events.”

The February 23 to March 8 weather event saw Brisbane receive 80% of its annual rainfall in just a few days, rivers burst their banks and hundreds evacuated in Lismore in northern NSW. The floods caused chaos in Sydney, and 22 died.

The record flood makes the case for investment in measures to lessen the impact of future events “even more compelling,” Mr Hall says, urging better planning to “no longer build homes in harm's way” and make buildings more resilient to the impacts of extreme weather, as well as removal of state insurance taxes which the ICA says discourages adequate insurance cover.

The ICA’s recent Building a More Resilient Australia report called on Australian governments to double federal funding to $200 million a year over five years, matched by the states and territories.

Catastrophe data company Perils last month estimated insured losses from the event at $3.99 billion and warned no common reinsurance market standard will apply, and event definition clauses will vary across reinsurers - with some including meteorological conditions and loss aggregation periods such as a 168-hour clause.

IAG, Suncorp and QBE have said their claims impact will be limited because of reinsurance programs.