WA Liberals branded 'financially reckless'

Western Australia's opposition leader has vowed to boost the state's public housing supply but is facing heat over his party's uncosted election promises.

Zak Kirkup on Friday pledged to build 4600 new homes over the next five years under a Liberal government.

The plan includes transferring 10,000 existing homes to the not-for-profit sector on a long-term lease which community providers can use as security for loans to build 2000 homes.

Mr Kirkup insists there is existing funding in the state budget to build the remaining 2000 homes but has declined to say how much it will cost.

The Liberals have refused to submit their policies to Treasury for costing, instead saying they will have them verified a week before the March 13 election.

Labor took a similar stance while in opposition in 2017, although their flagship Metronet train network had been costed by Treasury in 2013.

Early voting starts on Wednesday and more than a million voters are expected to cast their ballots before polling day.

Labor campaign spokesperson Rita Saffioti branded the Liberals "financially reckless".

"It's one thing to refuse to submit your policies for an independent analysis, but to not even attach any cost to your policies is just extraordinary," she said.

"Are Western Australians supposed to guess how much these commitments will cost?"

Mr Kirkup insisted the Liberals were simply following the convention for opposition parties.

"We'll be releasing our costings closer to the election which is exactly what happens every election," Mr Kirkup told reporters.

"That is the tradition, that's absolutely what we do."

Treasury costings this week revealed Labor's campaign promises will add $1 billion to the state's net debt over the next four years.

Labor's cost estimates for 126 commitments were considered reliable with only one minor discrepancy identified, Under Treasurer Michael Barnes said.

Homelessness has become a challenging issue for the McGowan government, which has been forced to deal with large tent cities arising in Perth and Fremantle.

Almost 16,000 people are on the public housing waitlist and there is currently forecast to be a net increase of just 47 homes over the next four years.

Mr Kirkup said the government had "continued to ignore" the homelessness crisis, adding that his policy would also boost construction jobs.

"We know that after the eviction moratorium ends in March and the subsidies and incentives from the federal government come to an end, the residential construction sector is telling us that there will be a housing cliff," he said.

"We're positioning this policy to make sure that our tradies have long, secure work into the future."