Rogue worksites are putting Australia's construction industry at risk by not following health guidelines to slow the spread of coronavirus.
The construction industry has been given the green light by the national cabinet to continue working during the COVID-19 outbreak.
Australia's unions are urging employers and staff to strictly follow the public health advice so construction can continue.
Electrical Trades Union national secretary Allen Hicks says reckless individuals may "stuff it up" for everyone else.
"There are some people out there who are treating this as business as usual," he told AAP.
"Some of the sites are doing an awesome job, others need a shot across the bow. If they are going to stuff this up they will stuff it up for the whole industry."
Mr Hicks zeroed in on Western Australia as one state where the message did not seem to be getting through.
"Without singling out any specific builders or contractors, Western Australia needs to lift its game," he said.
Construction workers would further clog the welfare system if building projects were suspended during the pandemic, Mr Hicks said.
"We are talking about hundreds of thousands of construction workers - it will put enormous strain on the welfare system."
SafeWork NSW on Thursday told AAP it had received 13 complaints about possible coronavirus exposure on construction sites.
Inspectors were enforcing coronavirus health guidelines during building site visits, a SafeWork spokesman said.
"Where on-site construction work is required, operators should put in place controls to ensure social distancing and positive hygiene practices can be maintained."
The construction union on Thursday said a Melbourne worker had been infected with coronavirus after travelling overseas.
The worksite was immediately shut down and no close contacts had displayed COVID-19 symptoms, the CFMEU said.
"All necessary procedures to ensure the health and safety of site workers were implemented," the union said in a statement.
CFMEU national construction secretary Dave Noonan says members are being urged to report any worksite not following coronavirus guidelines.
"The union has heard from members that some worksites are not changing their practices or setups to meet the hygiene and safety measures that have been advised by medical authorities and mandated by the government," he told AAP.
"This is not good enough. It is essential that the industry maintain all of the health and hygiene precautions that are required for construction workers to remain safe."
Mr Hicks said unions would only push for construction work to continue so long as health authorities said it was safe.
A group of 11 unions and industry associations on Wednesday issued a joint statement stressing the importance of keeping construction jobs running.
"As vital constituents of the economy, it is critical that all stakeholders of the building and construction industry work together to ensure the protection of employers, workers, their families and our community," the statement said.