About 1000 care workers will leave their posts on Sunday, demanding better pay and working conditions.
It's the longest strike so far for IDEA Services staff, in an eight-month-long dispute.
E tū union industry coordinator Alastair Duncan says the employer hasn't budged.
"Right across New Zealand we've seen issues resolved - midwives, teachers - and now these care workers need to be listened to. But we're not sure their employer is listening."
The workers want a formal facilitation process over workloads, job security and wages. IDEA, owned by IHC, says there has been "considerable planning" to ensure care continues through the strike.
"Wherever possible we are using the same people to cover shifts so that there are as few new faces as possible," said Joan Cowan, chief operating officer of IDEA Services.
"IDEA Services supports around 3000 people at weekends though some will return to family members for the day. Service managers, including me, will be in homes supporting people and national office staff will also be involved where appropriate."
IDEA Services staff care for people with intellectual disabilities, providing vocational and residential care.
"That means the workforce has to sleep over - they don't get a lot of private time to themselves," said Duncan. "It means they're working shifts, it means they're working weekends."
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The union says there have been two days of failed mediation over its wages. But Duncan says it's not just about pay.
"IDEA wants the right to move workers willy-nilly from workplace to workplace. That's not fair on the workforce, but it's also not fair on the people that they support."
The strike begins at 8:30am and ends 12 hours later. Details of what's happening on the picket lines are available on the E tū website.