A royal commission has heard more evidence of the construction union harassing building companies that didn't have enterprise agreements.

Dennis Milin, owner of construction company Milin Builders, told the commission that CFMEU ACT secretary Dean Hall told him he’d be the laughing stock of the union movement in Canberra if there was no agreement in place covering a Woden development the company was working on.

The union official told Mr Milin if his company didn’t sign up it would have trouble getting cement pours and other trades and there would be “all sorts of authorities and officials visiting to check you over”, Mr Milin’s notes of the August 2014 conversation show.

He asked Mr Hall if he was threatening the company.

“Of course not, we don’t do that, we don’t threaten anyone,” he says Mr Hall replied.

The union official went on to say he was worried the company would get negative publicity along the lines of “site picketed” or “bad unsafe builder”.

Mr Milin on told a hearing of the commission in Canberra he did take the conversation as a threat.

At the time, Milin Builders had been in protracted negotiations with the CFMEU to set up an enterprise agreement that covered all its work, instead of the site-specific agreements it normally used.

Those negotiations started in early 2013 and Mr Milin said that by the middle of the year he had signed an agreement and taken it to the union office where he paid an $800 fee and asked for it to be registered.

But the union didn’t register the agreement, with assistant secretary Jason O’Mara telling Mr Milin later that he’d been given the wrong instrument but now he had the right one and should sign in.

“I basically said no, you have stuffed me around … you’re treating us all like a pack of fools,” Mr Milin said.

The conversation got more heated with Mr O’Mara calling the builder a “f****** smart arse” and telling him, “You’re going to sign the f****** EBA.”

“I said you get f*****, you fat -” Mr Milin said, censoring himself.

He also gave evidence that Milin Builders had won a contract in 2012 to build the IQ Apartments on Northbourne Avenue in Braddon but was booted off the project after the union became a joint venture partner.

Mr Milin’s witness statement said that soon after the union started funding the project, Mr Hall told him he’d need an enterprise bargaining agreement and that the union only wanted to work with companies who would guarantee all sub-contractors also had agreements with unions.

Milin Builders employees gave evidence to the commission about officials from the CFMEU and the Communications, Electrical and Plumbing Union visiting their various construction sites and raising safety issues.

One visit, in April this year, resulted in site foreman Micah Beaumont calling the police about the disruptive behaviour of union officials.

By Katina Curtis