The Construction, Forestry, Mining and Electrical Union hopes the intervention-style approach could help ease the burden on health and legal services struggling to cope with drug addiction.

The first meeting in a planned Australia-wide consultation process took place in Canberra on Thursday afternoon.

The union has recommended mandatory blanket testing for drugs and alcohol on work sites several times a year without notice, using impairment assessors drawn from equal numbers of employer and employee representatives.

The ACT Government has asked the Work Safety Commissioner to work with the union, Master Builders Association and Housing Industry Association to reduce ice's impact on the capital's work sites.

The union has a long history of opposing drug and alcohol testing in the workplace, but shifted its position over members' concerns about the safety risks posed by workers impaired by addiction or substance abuse.

CFMEU ACT state secretary Dean Hall hoped the testing regime would be included in new Enterprise Bargaining Agreements within the next year.

Mr Hall said the prevalence and danger of the drug ice – which has been described as an epidemic - had prompted the proposal.

"Ice is a problem in society and the building and construction industry reflects society," Mr Hall said.

But he said the policy was not about catching and punishing users, but about the safety and rehabilitation of workers.

Mr Hall said the workplace had been proven to be one of the best places to stage interventions, and that early identification could help take pressure off the health and justice system.

He said, under the policy, workers with drug and alcohol issues could take leave for rehabilitation, with the promise their jobs would be waiting when they returned.

"It's a hell of a lot of motivation for a person to try and turn their life around if they know their job will still be waiting for them," Mr Hall.

"It says, we understand there's a problem, we don't want to sack you, we want to help you.

"It defers to them to sort themselves out so they can remain productive members of society."

CFMEU national construction secretary Dave Noonan said the policy focused on the causes of impairment, which could include fatigue, physical and mental health, job insecurity, injury and illness and drug and alcohol use.

"The union has worked on the ground in this space for over 25 years raising awareness, offering counselling and assisting people overcome addictions," he said.

"Our proposal is not punitive – it's about safety and providing support for people to turn their lives around.

"It's possible for people with substance abuse issues to get help and turn their lives around. It's not a life sentence."

ACT Workplace Safety Minister Mick Gentleman welcomed the CFMEU's initiative and said there were legislative barriers to the proposal.

"It has always been a question of the willingness of the industry partners to progress initiatives such as this one, and I have asked the Work Safety Commissioner to keep me updated on the progress of proposed drug testing."