Thirteen Derby school kitchens will remain closed after a gas safety survey revealed substandard ventilation and equipment too expensive to repair.
Derby City Council closed 33 kitchens earlier this month after a routine inspection revealed faults at four of the first five schools checked.
Most schools have now reopened their kitchens but 13 have been forced to close for good after being assessed.
Pupils will have hot meals brought in from other schools instead.
Council leader Harvey Jennings said: "There are 13 that we have identified that will not be safe to reopen in the future without significant investment. The equipment is that old because it has not been replaced over the years - we cannot physically go out and buy the parts for them."
Problems with some school kitchens in Derby first came to light after a small gas explosion which injured a member of staff at a school not connected to the current closures.
The explosion last year, in which a member of staff was slightly hurt, prompted similar kitchens to be closed but also began a rolling programme of checks, the council has said.
The schools affected are St Martin's, St Giles Special School, Bemrose Community, Leesbrook, Derby Moor, Shelton Juniors, Meadow Farm Primary, Rosehill Infants, Firs Primary, Lawn Primary, Redwood Junior and Ravensdale Junior.