CLEANERS are being balloted for strike action at 20 Kirklees schools.
Public sector unions GMB and Unison have declared an industrial dispute with building company Jarvis.
Talks broke down earlier this month after cleaning staff at the schools had their contracts transferred to Jarvis from Trident/OCS.
Jarvis wants cleaners to accept 48-week contracts, which union say will mean they will go unpaid for four weeks of the year.
A union spokesperson said in all other schools in Kirklees cleaners worked all the year round.
But in schools which are part of the private finance initiative (PFI) half the cleaners work four weeks less.
He said inevitably cleaning standards in schools would deteriorate and members would lose out on already low wages.
"Cleaners are only paid just over £5 an hour and could earn more at their local supermarket. It would cost Jarvis £400 per cleaner to put them on all-year round contracts. For a multi-million pound company that is getting enough money from the council to pay the full rate, this is penny pinching at its worst," he said.
The unions say they are now set on a collision course with Jarvis.
They are speaking to councillors who are pressing for an urgent meeting with the council's chief executive Tony Elson.
A Jarvis spokeswoman said they would investigate the concerns.