The Construction, Forestry, Mining and Energy Union unveiled the new policy on Thursday, calling for "blanket" drug and alcohol testing in a bid to stamp out illicit substances from the high-risk industry.

Union delegates nationwide will begin pushing building industry employers to agree to fund the new initiative in the coming enterprise bargaining period.

The move is at odds with the powerful union's previous stance on the issue in Victoria, where branch leaders attacked the former state government's mandatory testing code.

Dean Hall, the union's ACT secretary and one of the creators of the new policy, said the drug ice had become a "gamechanger" in the industry.

"Its prevalence is growing in society and its potency is growing exponentially," he said.

"There is an epidemic out there and people in the construction industry are using it."

Mr Hall, who worked as a drug and alcohol social worker for a decade, said he believed five per cent of construction staff had a substance addiction.

"I believe that's the case in the construction industry and society as whole ... one in 20 of us," he said.

"They are not all people who are ripping off your television – there are a lot of people who can function in various states of dependence – but we are a high-risk workplace where mistakes can not only lead to the death of that worker but other workers and the public."

Master Builders Association of Victoria has welcomed the CFMEU's support for drug and alcohol testing.

Chief executive Radley de Silva said a testing regime was "vitally important" on worksites where people under the influence could be free to operate machinery and endanger the lives of co-workers and the public.

"Master Builders has been calling for action on this issue," he said. "Every construction worker has the right not just to feel but to know they are operating in a safe environment."

The union said there were key differences between the new policy and the testing regime proposed by the former government in Victoria, which it claimed was "punitive" and ideologically driven.

The CFMEU's policy calls for mandatory saliva testing for all people on a building sites – including employers, construction workers, crane operators and tradesmen – instead of the previous code that required testing of 10 per cent of the workforce on public projects.

Opposition industrial relations spokesman Robert Clark said the policy was a "welcome change of heart" by the CFMEU but an embarrassment for the Labor government, which previously trashed requirements for on-site testing.

"It's clear that when CFMEU tells Daniel Andrews to oppose drug and alcohol testing he opposes it, and now when they tell him to support it he welcomes it." he said.

"The Coalition was consistently focused on safety but Daniel Andrews is dancing to the tune of the CFMEU."

Mr Andrews said the previous government's policy was a political weapon in the campaign against the CFMEU.

"It was about ideology, it wasn't about better outcomes," he said.

The Abbott government has criticised the CFMEU's new policy as an attempt to court crossbench senators ahead of a vote on laws to extend the coercive powers of the building industry watchdog, the Fair Work Building and Construction inspectorate.

"This proposal regrettably seems to be a desperate attempt to court crossbench senators and draw attention away from the CFMEU's appalling record of intimidating workers and making excuses for dangerous behaviour on work sites," Employment Minister Eric Abetz said. "The CFMEU's proposal is rushed and half-baked."

Mr Hall said the workplace had been proven to be one of the best places to stage an intervention and hoped the proposed regime could ease the burden on the courts and medical system.

Meanwhile, Liberal MPs in the state's west are also calling for shearers to be drug-tested at work, amid concerns about widespread use of ice.

- with Marissa Calligeros