Western Building Systems says they have 'serious concerns' about how long a proposed independent review of the schools building programme will take.
The company says independent and expert answers are needed to avoid potentially 'irrevocable' damage to the programme.
It emerged this week that 17 schools have been assessed as needing 'some permanent remediation work', despite having been cleared for use with no precautionary measures last October and November.
Temporary measures, including scaffolding and safety fencing are being put in place at the schools to make them safe for the coming year – with permanent repairs to get underway over the summer holidays in 2020 and 2021.
In total, issues have been identified at 40 schools built by Western Building Systems on behalf of the Department of Education.
The Department of Education has said a promised independent review into the design & build programme will only commence once the 'ongoing legal process' has finished.
A review on models used internationally is set to be completed by the end of the year, with a procurement process for the organisation to carry out the review 'nearing completion'.
In a statement today, Western Building Systems said they're still awaiting details of the terms of reference, the independent chair or investigators, and international best practice guidance.
The contractor suggested several questions have been raised - including why schools previously certified by the department's own assessors were suddenly deemed to have defects.
They've said they have "little further understanding nor have had input" into the planned independent review process.
They say the will again write to the Minister for Education and Skills seeking a firm deadline for the publication of the independent report.
The statement notes: "We continue to engage with the Department to better understand the nature and severity of the issues at these school - however we have serious concerns now over how long such an independent review will take.
"Instead of decisiveness and openness, we have distraction and secrecy. The approach appears to be publicly scapegoat WBS and hide behind the cloak of potential legal prejudice when it is beneficial."
They add that they are committed to working with the Department to "resolve the issues on all schools identified".