HALF of primary schools spent more last year than they received in income, with parents being pressed to help with funding.
Another one in five (22pc) barely broke even in the academic year to August, according to research for the Catholic Primary Schools Management Association (CPSMA).
And the financial pressure is worsening after Education Minister Ruairi Quinn said the minor works grant for schools won't be paid this year.
One school has been forced to text parents to tell them to put extra layers of clothing on their children for warmth, as they struggle to cope with funding cutbacks.
The principal of Our Lady of the Wayside national school in Bluebell, Dublin, told how children sometimes wear coats in the classroom as they have "no money" to pay for their struggling heating system to be serviced.
Anne McCluskey, who is in her sixth year as principal at the school deemed disadvantaged by the State, said the problems paying for the minor repair works at her 120-pupil school were being mirrored around the country.
Ms McCluskey said the school simply did not have the money to pay for the day-to-day repair and maintenance jobs.
Each morning, she goes out to try and "kick-start" the boiler.
The Irish Primary Principals' Network (IPPN) has urged the Department of Education to reinstate the vital minor works grant – worth €8,000 to a school for maintenance – which was slashed in the last Budget.
The CPSMA survey, conducted by Amarach Research, found over nine in 10 schools (93pc) received a minor works grant last year to carry out essential repairs.
But now schools are losing out because of cuts in state grants, and also the additional monies that most raise through other sources such as voluntary contributions and fund-raising.
More than eight in 10 (86pc) schools rely on ad-hoc fundraising, while four in 10 (43pc) ask parents to make an annual voluntary contribution.
However, in more than half of cases (57pc), the amount of additional monies received by schools from these other sources last year was down on the previous year.
The survey was carried out among 540 primary schools over a period between October and November.
CPSMA general secretary Eileen Flynn said schools at primary level were always the "poor relation" in terms of funding, even in times of plenty.
But now they could not even make ends meet, she said.
With the Budget due next week, Ms Flynn warned that any further cuts to school finances would be "devastating".
Sean Cottrell, director of the IPPN, said: "Back in the 70s and early 80s, we saw some awful pictures on television of schools with rat holes.
"We will be heading back to that, there has been a lot of good money spent over the past five years on school buildings but we will lose that benefit if we don't maintain them properly."