Parents and pupils at a primary school whose classrooms have been declared potentially lethal are protesting outside council offices.
Safety inspectors say the classrooms fall below legal standards
A safety report into three portable classrooms at Ysgol Coed Y Gof found they were in such a poor state that staff and pupils could be killed.
The units at the school in Pentrebane, Cardiff, have rain leaking through the roof onto electric switches.
Cardiff County Council has said it is looking into the situation "urgently".
The problems were highlighted in a health and safety inspection earlier this year carried out after complaints by parents.
Children in Years 5 and 6 are normally taught in the classrooms.
Protest organiser Sue Riley, whose granddaughter attends the school, told BBC News Online the demountable classrooms were supposed to be a temporary measure when they were erected over a decade ago.
"We were told they'd be there for a year," she added.
"They smell, they're full of condensation - you wouldn't keep an animal in there.
"We had part of an extension five or six years ago but then we were taken off the capital programme," she said.
The safety inspection found:
- Water leaking into the classrooms and the electric switches and lighting with the possibility of "electric shock which has the potential to lead to fatality";
- the possibility of floor collapse due to rotting;
pools of rainwater on the class floors which pupils mop up before starting schoolwork;
fire exits difficult to open because of swelling to the door;
inadequate ventilation causing condensation and mould in classrooms.
In a statement issued on Thursday the school said: "We understand the concerns of parents and we want to assure them that the safety of the children and staff at Ysgol Gymraeg Coed Y Gof is of paramount importance.
"Which is why every action is being taken to address health and safety issues in the demountable classrooms.
It read that the school had made arrangements for the children to be taught in the main building whilst work on the buildings took place.
"Meetings have taken place between Council officers and the head teacher, parents and governors of the school," it read.
"The question of any further investment in the building will be considered bearing in mind the surplus places in the school and others across the city."