Dr Philip Dixon, the ATL director, said a survey of members showed almost half felt the condition of their school or college was "poor" or "very poor" and posed a risk to the health, safety, security and well-being of staff and pupils.
The call for a review will be made next week at the Wales TUC conference in Llandudno. The ATL wants a commitment that all schools will be fit for purpose by the end of the new Assembly's term.
A pledge to bring every school up to an adequate standard by 2010 was abandoned at the end of the previous administration by Jane Davidson, education, lifelong learning and skills minister.
So acute is disrepair at Cowbridge comprehensive in the Vale of Glamorgan that governor Martin Blamey wants private finance initiatives to be considered - despite England's spiralling costs and maintenance problems.
But Dr Dixon called for talks between the Welsh Local Government Association and the minister to resolve the crisis.