About 250 Bunnings workers have walked off the job in their fourth strike this year to protest a proposed roster system change.
Staff from 21 stores met this morning and FIRST Union spokesperson Morgan Godfery said he expected more than 800 workers would strike by the end of the week.
Under the current collective agreement roster changes have to be a mutual agreement between managers and workers, but Mr Godfrey said Bunnings wanted to give managers the power to impose rosters.
"The big concern among workers is really how are you meant to plan your family life when you don't know when you'll to be home, how can you go to your children's school prize giving if you've lost control over the times you work," Mr Godfrey said.
"People are basically saying - how are we meant to control our life outside of work if we don't know when we'll be rostered on?"
Bunnings has said that if a roster change was needed, then workers must be consulted and given four weeks notice.