Council leaders are to review future inspections of Norfolk schools - after only visual checks were done on potentially dangerous ceilings in previous surveys.
Urgent repairs are needed at 15 schools after the collapse of a ceiling triggered 60 emergency inspections at buildings Norfolk County Council is responsible for.
But there have been questions about why issues were not picked up during the council's rolling four-year programme of inspections.
And Penny Carpenter, cabinet member for children's services, told the BBC inspectors had only been doing visual checks and not removing ceiling tiles to check for problems behind them - until the recent emergency surveys.
Those emergency inspections were triggered after the partial collapse of a lath and plaster ceiling - which can lose their structural integrity, particularly if wet - at the Synergy Education Trust-run Fakenham Junior School.
Mrs Carpenter said there would be a review of the inspection regime following the recent incidents.
A county council spokeswoman said the regular inspections were done by the council-owned NPS Property Consultants and were "largely visual" in line with Department for Education (DfE) guidance.
She said: "DfE guidance on assessing the condition of the schools' estate sets out that condition surveys are normally non-intrusive and there is no specific mention of lath and plaster or suspended ceilings.
"We did not know this was an issue until the partial collapse of a ceiling at a Norfolk academy.
"The inspections we have carried out subsequently would be classed as intrusive and have identified issues at 15 of our schools."
But Labour councillors said the Conservative-run council must take responsibility and urged leader Kay Mason Billig to make a statement at Monday's cabinet meeting.
Mike Smith-Clare, deputy leader of the Labour group, said: "Inspecting buildings properly is fundamental to high standards. The county council has responsibility for ensuring inspections of buildings are carried out rigorously and regularly. This clearly hasn't happened."
There was a three-day closure at Avenue Junior School after issues in six classrooms, while a similar discovery led to the closure of a classroom at Parkside School in Norwich for a day.
Children from Woodton Primary, near Loddon, are having lessons in the village hall because of concerns over the ceilings in their school.
Which schools need to be repaired?
The 15 schools identified as needing repairs are:
Avenue Junior School, Norwich
The Parkside School, Norwich
Freethorpe Community Primary and Nursery School
Bacton Primary School
Brooke VC CE Primary School
Hainford VC Primary School
Woodton Primary School
Horning Community Primary School
Ludham Primary School and Nursery
Terrington St John Primary School
Tilney St Lawrence Community Primary School
Ellingham CE VC Primary School
Walpole Highway Primary School
St George’s Primary & Nursery School, Great Yarmouth
Hevingham Primary School
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