Half of headteachers say parts of their school are either out of use or unfit for purpose due to leaks, damp, mould, asbestos, ageing boilers and malfunctioning fire doors, according to a new survey by the National Association of Head Teachers(NAHT).

Among those who say their schools are suffering, almost three-quarters (73%) say they have toilet blocks that are either closed (8%) or not fit for purpose (65%).

“I have toilets that urgently need replacement, and I do not have the funds to do so. There is a collapsed drain and every time it rains the playground is flooded,” one headteacher said.

Two in five (41%) say facilities at their school reserved for children with special educational needs and disabilities (Send), including dedicated classrooms, sensory rooms and outdoor spaces, are unfit for use.

The findings come at a time when the government is proposing reforms to the Send system, which will require mainstream schools to expand and improve provision for children with special needs.

Of those with buildings unfit for purpose, almost two-thirds (64%) say their playgrounds were unsuitable (56%) or closed (8%). “We have rooms that are closed to children, walls covered in mould, a leaking roof, sinking floorboards, unfit windows and a condemned playground,” said another head.

The poll, though small with just 326 participants, provides a vivid picture of the problems facing headteachers with crumbling, outdated buildings. One school leader said they lay awake at night worrying about the school fire doors. “I would say around 80% are non-compliant,” they said.

Another respondent said: “I have been screaming about the poor state of my boilers, but nothing happened until they totally stopped working and I had to shut the school as it was too cold.”

Almost all of the headteachers who took part (96%) said they did not receive sufficient capital funding to maintain their school’s buildings. The National Audit Office has said it will cost £14bn to restore school buildings in England to a satisfactory condition.

Paul Whiteman, the NAHT general secretary, said: “We know the UK government inherited a school estate in a mess, and we recognise there is additional investment planned through the new 10-year estates strategy. This survey shows the sheer scale of the challenge ahead, especially with the prospect of events in the Middle East fuelling inflation.”

NAHT members will debate a motion at their annual conference in Belfast later this week, calling on the union’s national executive to lobby the government to fully fund essential capital expenditure across all state schools in England.

A Department for Education spokesperson said: “We are already turning the page on years of decline in the school estate – fixing a legacy of neglect, committing to removing Raac [reinforced autoclaved aerated concrete] for good and delivering a decade of national renewal.

“Schools have had to patch and mend buildings for too long – that ends under this government. For the first time, we are providing long-term investment, rising to almost £3bn per year over the next decade, to improve the condition of our schools and colleges.”