Major damage has been caused by the harsh winter at the construction sites of all four Bradford secondary schools being rebuilt in the latest phase of a multi-million-pound scheme.

Water inside under-floor heating pipes at each partially-built school froze, cracking the pipes and concrete floor slabs laid over them as temperatures repeatedly plunged below zero.

Bradford Council confirmed the situation occurred after contractors had filled the heating systems with water to test for leaks before they were covered in concrete.

The true extent of the damage and the repairs needed is still being assessed.

But it has led councillors to question how the situation was allowed to happen with one saying that it seems someone has missed some very basic ABCs of household maintenance.

Bradford Council has insisted it will not bear any of the additional costs, which are likely to be substantial.

The affected school sites are: Grange Technology College in Bradford Hanson School in Bradford Beckfoot School at Bingley Greenhead High School in Keighley.

The schools are being rebuilt as part of the second phase of the Council’s Building Schools for Future (BSF) programme which is costing £400 million.

The BSF scheme is being delivered by the Local Education Partnership, known as Integrated Bradford.

A company called Educo, a consortium of construction giants Costain and Ferrovial Agroman, is responsible for the design and building work.

Cindy Peek, the Council’s deputy director of services for children and young people, said: “We acknowledge there has been an issue with the four new secondary schools which are being built in this phase. Unfortunately, damage was incurred to the concrete floor slabs during the recent extreme weather conditions.

“We are obviously disappointed that an element of the work carried out on our Building Schools for the Future phase two secondary schools has encountered a problem.

“This will be rectified by the contractor as part of the construction process and will not affect the quality of the completed schools. The cost of any repair will not be borne by the Council.

“Technical solutions are being tested by the contractor, Educo, at the moment as the weather is getting warmer.

“Once this has been done we will be able to discuss the overall impact. In the meantime the contractor is still working on all the sites and work is progressing.”

But councillors involved in education in Bradford have questioned how the situation was allowed to happen.

Councillor Ralph Berry, Labour’s education spokesman, said: “It seems to me that someone has missed some very basic ABCs of household maintenance.

“When temperatures drop water freezes, and ice expands. Any GCSE physics candidate could tell you what’s gone wrong here.

“It raises a question about the oversight of the programme.” Councillor David Ward, education spokesman for the Council’s Liberal Democrat group, said: “The important thing is that the repair work is paid for by those responsible and the project is back on track as soon as possible.”

Mrs Peek said she was otherwise pleased with the progress being made across the school sites. “The primary special schools in this phase have been completed to an extremely high standard and they are officially opening on new sites alongside mainstream schools after Easter.

“We are also delighted that Merlin Top Primary School in Keighley has already opened and is making a real difference for children, parents and staff.”