The opposition has accused the ACT Education Directorate of poor planning after it revealed 37 public schools have demountable classrooms, some of which were installed in the 1980s.
In a response to questions taken on notice during budget estimates, the directorate released a full list of schools which had the temporary classrooms and their installation dates.
The oldest transportable building is a three-classroom unit which was built in 1974. It was originally installed at the former Scullin Primary School and was relocated to Miles Franklin Primary School in 1984.
Narrabundah College, which is undergoing renovations to remove asbestos-riddled buildings, has the most temporary classrooms in the territory at 22 units.
Neville Bonner Primary School in Gungahlin opened in 2013 and received its first transportable classrooms four years later. It now has 12 transportable classrooms.
Garran Primary School had three new transportable units installed at the beginning of this year, bringing the total to eight temporary buildings on that campus.
Amaroo School and Ngunnawal Primary both have seven demountables while Palmerston, Fraser, Franklin and Campbell Primary Schools have six units each.
Some schools have had temporary units for almost 40 years, including Miles Franklin Primary (1984), Gowrie Primary (1985) and Fadden Primary (1986).
Other schools had the units installed in the 1990s, including Gordon, Theodore, Charles Conder and Calwell Primary Schools and Caroline Chisholm Senior School.
Opposition education spokesman Jeremy Hanson said the long-term reliance on transportable classrooms showed a failure in management of existing school infrastructure.
"It's all a bit ad hoc," Mr Hanson said.
"My advice was they're only meant to be there for five years.
"They're not temporary, they're just fabricated classrooms."
Mr Hanson said the squeeze wasn't just being felt in rapidly-growing Gungahlin schools, but established schools such as Garran Primary were having more units installed which were taking up valuable playground space.
A spokeswoman for ACT Education Minister Yvette Berry said schools often chose to keep demountables longer term for different purposes.
"Transportable learning spaces are an effective and flexible way for schools to respond to fluctuations in enrolments," the spokeswoman said.
"Transportables are often planned to be used on a temporary basis, however this can change according to the needs of a particular school, including shifts in enrolment demand.
"Where that is the case, transportables provide time to plan for permanent expansions where needed for the long term."
The spokeswoman said the nearly 50-year-old demountable classroom at Miles Franklin School was valued as an additional learning space, even though the enrolment growth peak had passed.
She said the temporary classrooms at Narrabundah College would be removed as part of the expansion, but timing would be confirmed in future ACT budgets.
The spokeswoman denied the Education Directorate had been caught off-guard by rapid school population growth in Gungahlin.
"The use of transportables to respond to enrolment growth and fluctuations in public schools is standard practice across Australia.
"Transportables are also a cost-effective and more flexible way to respond to population growth and movement."
She said the directorate would engage with individual school Parents and Citizens Associations about specific situations at their schools.
The Legislative Assembly education committee has launched an inquiry into the management of ACT school infrastructure, including capacity issues and use of temporary facilities.
