The ACT Education Directorate said friable asbestos was present in the double storey classrooms at Campbell Primary School and Narrabundah College, meaning the aging infrastructure could not be safely upgraded.

The directorate said the buildings would instead be demolished and replaced as part of a school modernisation program.

Lessons for affected students would be relocated to demountable classrooms, set up on school ovals, until new facilities could be built.

The announcement comes 34 years after Narrabundah College students won a battle with the federal government – who at the time managed ACT public schools – to have blue asbestos removed from the school.

In September 1983, the students marched from the Jerrabomberra Avenue college to Parliament House to demand action on the deadly substance on their classrooms.

The students' protest was rewarded by an announcement that sealing and removal work would be completed to ensure a safe learning environment.

This week, students at the college again erupted with cheers and applause when told of plans to replace the aging infrastructure.

Both Narrabundah College and Campbell Primary were built in the early 1960s when asbestos was a common building material.

A directorate spokeswoman said the contamination was in the ceiling space, wall cavities and sub-floor of some buildings.

She said the asbestos was part of the fire retardant sprayed onto the structural beams during the construction of the buildings.

Removal works were completed in the mid-1980s and early 2000s, however residue still remained within some ceiling space and wall cavities, she said.

The directorate said a consultant had been monitoring the schools to ensure the safety of students and staff, and tests had confirmed no asbestos had been detected in the air.

The safety monitoring regime would continue until the demolition had been completed.

A fact sheet, published on the directorate's webpage, said the asbestos was not the same as that found in Mr Fluffy homes.

Friable asbestos is a form of asbestos that can be crumbled or reduced to a dust by hand when dry.

"Therefore friable asbestos can, when not dealt with appropriately, represent an exposure hazard," the directorate's online explainer said.

"If however it is inaccessible and well-sealed, it can't be disturbed during normal building use and therefore doesn't present an exposure risk."

Narrabundah College, built in 1961, will lose about half of its teaching space with three double storey classrooms (Block B, C, and D) contaminated with the deadly material.

Asbestos has been located in a double storey classroom (Block B) and single storey annex at Campbell Primary, built in 1965.

"Some buildings at both sites are nearing 60 years of age and have reached the end of their useful life," the directorate information page said.

"Over time, the fabric of the buildings has altered and walls are subject to cracking.

"Due to friable asbestos material being present, some of the existing buildings cannot be upgraded. Therefore these particular buildings will be safely demolished."

The online information pack said the demountables would be installed at Campbell Primary later this term and at Narrabundah College early next year.

"New transportable learning spaces will be located at both schools to allow for the relocation of classes from the affected buildings.

"The transportable buildings will be modern buildings and will be heated and air-conditioned.

"The school community will be informed about the progress of the works including the recommended location for the transportable buildings.

"However the location will ultimately be determined by the building expert advice to ensure appropriate access to power, water etc. is available."

Ultimately, the directorate said the demolished classrooms would be replaced by "new learning areas developed to offer modern learning spaces".

ACT Council of Parents and Citizens Association chief executive Terry Sanders said the directorate had advised the association of the proposal and transition arrangements.

"We're quite comfortable with that," he said.

"We'll certainly be keeping an eye on it … [but] we're confident everything will run smoothly."

The directorate said it would work to involve the community in the planing and design of the new learning spaces.

Narrabundah College principal Kerrie Grundy the school would host an information booth on October 25 about the plans

Ms Grundy said students erupted with cheers and applause when told of the redevelopment.

"We're going to get brand new demountables on the oval, purpose build for our college, which means the students will be in a more comfortable environment.

"They're thrilled about that and keen to go on this journey.

"They understand that these buildings are tired and old, we can't refurbish the buildings so we're on a journey to refurbish the school.

Ms Grundy said the redevelopment would not affect the school's programs, classes or timetable.

"The school will continue to operate at a high level, we'll just be on the oval."