A total of 390 new special classes have been sanctioned to open in schools for next September according to the latest National Council for Special Education (NCSE) figures.
Most of the new classes are for autistic children.
But some schools that have agreed to open special classes have expressed concern that they are coming at the expense of other vital provisions for vulnerable children.
They say other important programmes are being displaced as schools are told to make space for the new classes.
Principals of three primary schools all share this concern.
St Malachy's Senior School in Dublin’s Finglas is a DEIS school that has agreed to open two special classes for the coming school year.
It agreed after the NCSE told the school following a visit that it had identified three spaces that are not currently being used for teaching and learning.
St Malachy’s has spare capacity due to falling demographics in this old established suburb of the capital.
For a long number of years a private crèche has been operating out of one classroom, at a nominal rent.
"We are looking at a situation where we will not be able to open the school."
The children’s charity Barnardos also rents a former classroom in the school.
In order to make room for two new special classes, St Malachy’s has been obliged to give notice to both the crèche and Barnardos.
They have told them they have to leave by the end of this month.
'We have no money', says principal
The school says it will feel the loss of Barnardos particularly acutely.
As well as providing vital supports to families in this area, and training for school staff, the charity was also paying rent of €10,000 annually to the school.
To put that in context, the school receives €29,000 in capitation funding from the State.

"That is a very vital revenue stream for us and it will be gone", says the school's principal Michelle Eustace.
Outlining the expenses this 1970’s breeze block construction school faces, she says she had just paid an electricity bill of €3,600 for one month alone.
"I am two gas bills away from not having any money. That is where I am at financially.
"We have no money. We are looking at a situation where we will not be able to open the school."
Ms Eustace is at pains to point out that she is absolutely supportive of the opening of special classes.
It is just that there is a price to be paid and she feels it is pupils currently at the school who will pay that price.
"I fully understand the need for these classes," she says.
"I will open them and I have no doubt we will do a great job.
"I have two fantastic teachers who have volunteered to teach in them. But where is the recognition and the voice of the other 145 children we are looking after?"
No provision made for construction of special class
Across the city, on Dublin’s south side, another school that is among those sanctioned to open one special class has similar concerns.
Despite the fact that it is housed in a building constructed in very recent years, no provision at all was made in its design or construction for a special class.
It is a stark reminder of the lack of planning that has led to the current explosion of demand from parents.
This school did not wish to be identified. It too received a letter from the NCSE identifying spaces that according to the NCSE were not being used for teaching and learning.
But this school disputes this. It says it has no spare capacity.
"We are going to have to shoehorn in this class," the principal says.
It will have to lose either its library or a very small 'nurture’ room in the process.
The school’s library is used for English as an Additional Language (EAL) classes and for paired reading where older children support younger children by reading with them.
"Some children are coming in hungry and hunger is a huge trigger and a barrier to learning, but we are going to have to pull the breakfast club."
In this disadvantaged school the ‘nurture’ room is a space used to teach vulnerable traumatised children how to self-regulate.
This is a practice common now across DEIS schools who say that without the ability to self-regulate these children cannot hope to access teaching and learning.
Schools facing 'robbing Peter to pay Paul' situation
This principal too is keen to stress that she is happy to open a special class and has agreed to do so.
She knows they are needed but she is extremely concerned that the class is not coming as an 'add on' but at the expense of valuable work this school is already doing with very vulnerable children.
Both principals describe a ‘robbing Peter to pay Paul’ situation.
St Oliver Plunkett's Junior National School, also in Finglas, already has one special class and last week it agreed to open a second.
That same week it was informed that funding from Tusla to run its breakfast club has run out.
This means that after Easter the school will no longer be able to offer breakfast to its pupils.
Read more: Minister for Education will compel schools to open special classes
Although the loss of the breakfast club is not directly related to the opening of the special class, principal Ursula Reilly feels the contrast acutely.
"There are children coming in to school who have severe emotional and behavioural needs and have trauma," she says.
"Some children are coming in hungry and hunger is a huge trigger and a barrier to learning, but we are going to have to pull the breakfast club."
Like the other school principals Ms Reilly is concerned that rather than these special classes being ‘additional’ in schools, they are displacing other vital services for children whose needs she says are "just as great".