A row over unusually shaped classrooms has prompted teachers to take two days of strike action at a historic Roman Catholic boys’ school.

Two-thirds of the 60-strong teaching staff at St Aloysius’ College in Islington, north London, walked out of lessons to protest about what they describe as a “ridiculous” new extension, built under the Building Schools for the Future (BSF) programme.

Teachers have complained that the L-shape of the design and technology classrooms is “woefully inadequate” and “dangerous” as it does not allow teachers to see their pupils at all times, even when using potentially lethal tools.

They have also complained that the technology, art and science classrooms are too small, do not have enough natural light and lack basic storage, including lockable cupboards for chemicals.

Headteacher Tom Mannion told a public meeting that the #163;17 million rebuild, which will involve the demolition of an existing block, had “significant problems” with the design and technology classrooms.

“We all agree that the facilities provided by the Islington contract are in some cases inadequate and in other instances totally unacceptable,” he said, according to a local newspaper report.

Union members have said that no one has been prepared to take the blame for the poor design of the new buildings and are calling for the school, council and contractors Balfour Beatty to hold “productive talks” to solve the problem.

Teachers have proposed moving back into the old block, instead of demolishing it, until a solution can be found.

Paddy Marshall, NUT acting regional secretary for London, said there had not been enough consultation with staff at the design stage.

“That vital step in the process didn’t happen. Now everyone is trying to point the finger at somebody else,” he said.

Contractors Balfour Beatty said the safety of pupils was its “priority” and that the designs had been created while “working closely” with school representatives.

“In developing the design we have met and delivered the council’s requirements,” it insisted.

The row has echoes of other recent disputes and scandals surrounding new school buildings.

A number of academies have been criticised in the past for their futuristic designs incorporating a lot of glass, causing them to overheat in summer and become too cold in winter.

In other cases, heads of a number of other schools built under the private finance initiative (PFI) have complained about poor upkeep and maintenance of their buildings.

On Monday, Education Secretary Gove announced that the BSF programme, which he has previously described as “inefficient” and “wasteful”, has been frozen and a review of projects currently in the pipeline will take place.

Bespoke designs, agreed between schools, councils and contractors, are expected to be replaced by “off-the-peg” alternatives.

Some 150 schools in England have had BSF investment since the scheme began in 2004, according to Partnerships for Schools, the body charged with running the scheme for the Government.