The Department of Education says 19 schools have been cleared to open in full without any further works needed, following structural assessments.
It says all schools constructed by Western Building Systems (WBS) have now been assessed.
Out of the 42 schools, 19 have been cleared to open in full without intervention - while a further 19 schools can also open following external measures, in the form of a fence around the building and protective decking.
Source: Department of Education and Skills
Three schools can only open at ground floor level, following the implementation of internal engineering solutions and external precautionary measures.
Source: Department of Education and Skills
While one building, which is part of Ardgillan Community College, is to remain closed.
Education Minister Joe McHugh says: "The project managers, structural engineering teams and department officials have been working intensively to enable the finalisation of all structural assessments today and to give the necessary clarity to school authorities and communities.
"Right throughout this process, our overriding priority has been the safety of school students and staff.
"This has led us to adopt a very cautious approach and to initiate precautionary interventions where structural issues have been identified during the assessments."
He adds: "In cases where precautionary external or internal interventions are being implemented, this is with the purpose of ensuring the safe occupation of all or part of the building, and ensuring that disruption to classes is minimised."
The next phase will involve more detailed assessment and, where required, permanent works to fully rectify any issues.
By Friday, contractors will move to implement precautionary measures at all schools where this is required.
The department says the target is to have these completed in time to facilitate schools re-opening after the mid-term break.
Arrangements are also in place to ensure that school principals are kept fully informed of progress on a daily basis.
