Education leaders have defended forcing more students into demountable classrooms for the upcoming school year, blaming predecessors' poor planning.
Figures suggest more than 13,000 demountable classrooms are used in NSW, Victorian and West Australian public schools alone.
NSW Education Department secretary Murat Dizdar said a slight increase was expected due to new schools opening in growing communities and the unexpected destruction of an outback school.
"We'll always have the need for them," he told reporters on Thursday.
"The quality and calibre of those demountables ... are phenomenal - to the point where schools often reluctantly ... let go of them."
Education Minister Prue Car, trying to spruik a maintenance blitz across more than 800 public schools over the summer break, complained of a lack of forward planning for many high-growth areas in Sydney's northwest and southwest.
Opening schools of demountables while permanent buildings were constructed was "an absolute game changer" for families in areas where no public school was available for tens of thousands of residents, she told reporters.
"(People) have migrated from around the world to live in this country, to live in the outer suburbs of Sydney, and now, finally, they have a government that's building the schools that they need," Ms Car said.
But former NSW education minister Sarah Mitchell expects families will wait longer to get the schools they need under Labor after a slowdown in new project numbers in the latest budget.
"There's a certain irony in Labor speaking about the need for demountables when they were extremely critical of them in opposition," the Nationals MP told AAP.
The Australian Education Union described a "proliferation" of demountable classrooms in public schools in a 2024 report.
The report pointed to figures showing one in eight public school classrooms in NSW was a demountable in 2020, with the total portfolio exceeding 5000 by 2022.
Victoria meanwhile had 5761 demountables in 1130 public schools, the report said.
The WA government told local media in August it had 3006 demountable classrooms.
The Victorian government describes demountable or relocatable buildings as a cost-effective, flexible and rapid means of supplementing existing classrooms in schools with fluctuating enrolments.
While anecdotally demountables are thought to be inferior learning environments, a NSW education department research paper in 2015 found there did not appear to be any studies that specifically compare the difference in performance between students in demountable and permanent classrooms.
The stigma of demountables however appeared to affect both teacher and student attitudes, it noted.
