The State has spent more than €86 million over the past three years hiring prefabs for schools for use across every county.
The Department of Education said it has spent more than €5 billion on school building or improvements since 2020 and was actively trying to reduce expenditure on temporary accommodation.
However, figures show that prefab spending has remained consistent over the past three years with around €29 million being paid out annually.
The figure for last year was €28.8 million and covered the cost of prefabs at 440 different schools across the country.
Expenditure was highest in Dublin where €6.3 million was paid for the use of temporary buildings at 83 separate schools.
In Co Cork, a sum of €3.7 million was paid for prefabs at 54 schools while expenditure in Co Meath came in at €2.4 million for 26 schools.
Other counties with €1 million or more in expenditure on temporary accommodation last year included Donegal, Kerry, Kildare, Louth, Tipperary, Wicklow, and Westmeath.
The lowest level of spending on prefabs was in Co Wexford, where the State paid €263,000 for facilities at three schools.
A similar figure of just €264,000 was spent in Co Monaghan while the total bill for Co Roscommon was around €308,000.
The average nationwide cost per school was just over €65,000, according to the database of expenditure provided by the Department of Education.
Asked about the use of prefabs, the department said 350 school building projects - including 37 new schools - were currently under construction.
The department said: "Rental accommodation agreements are largely a legacy of the period of rapid demographic growth over the last decade."
The Department of Education added that a variety of factors, such as increased demand for special educational needs and the arrival of children from Ukraine, had required "accelerated delivery", including rentals.
An information note said: "To meet these needs quickly, in some instances temporary prefabricated units have been used.
"Rental of accommodation may also be the most appropriate and cost-effective option where an identified need is short term."
The department said that on a yearly basis, prefab expenditure represented about 3% of the total budget for school building projects.
It said temporary accommodation was also used in cases in which a major school project was planned and that older prefabricated buildings were being replaced over time.
