Wellington East Girls' College is to close its main block after it was found to be below the standard required to withstand a moderate earthquake.
Wellington City Council identified the main block and the school's hall as being potentially quake-prone buildings in 2008.
An independent engineers report commissioned by the Ministry of Education has confirmed both are below the standard required - the main block considerably so.
Principal Sally Haughton says the block, which is used for teaching and administration, is three storeys of unreinforced masonry.
Ms Haughton says the school is trying to minimise disruption, although the building does not pose an imminent risk.
The school has a teachers only day on Friday and Year 9 students will have an extra week of school holidays next week as arrangements are made to find alternative classrooms.
The Education Ministry says it will pay to fix the buildings and the work falls into its programme of ongoing earthquake strengthening.
Property policy manager Jerome Shepherd says it has taken so long to get to this point because the Wellington City Council did not initially red-sticker the buildings.
A former principal of Wellington East Girls' College says the buildings identified by the ministry's engineers report as needing majo quake work were strengthened in 1988.
Janice Campbell, who retired as principal four years ago, says both buildings were retro-fitted to withstand a magnitude 8 quake.
Several other schools whose buildings were strengthened at around the same time may now find themselves in the same position, she says.
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