Hospital patients’ safety is being put at risk by fires, floods and crumbling, overcrowded buildings caused by a £4bn government squeeze on capital funding, NHS bosses are warning.

Hospitals say they do not have the funding to replace outdated scanners, fix leaking roofs and boilers, or remove ligature points that suicidal patients may attempt to use to try to end their lives.

Four out of five (82%) chief executives and chief finance officers at NHS trusts in England fear the lack of capital funding poses a medium or high risk to patient safety.

Almost all (97%) of the 161 bosses surveyed by NHS Providers, which represents NHS hospital and ambulance services, are worried by how much money their trust needs to undertake urgent repairs. Almost as many (94%) are concerned their inability to tackle problems is affecting patients’ experiences of care.

Separately, Kettering general hospital said increasing demand meant its A&E unit was often so overcrowded that staff could not clearly see some of the sickest patients, making proper monitoring of their conditions difficult.

The unit was built in 1994 to handle 110 patients a day but now treats as many as 300 during busy periods. That mismatch has led to significant overcrowding, delays in treatment, children having to wait in corridors and ambulances having to queue outside A&E before handing patients over, which in turn hits 999 response times.

NHS chiefs’ concern over the mounting disruption, linked to a lack of capital funding, comes after ministers diverted more than £4bn of those funds into the NHS’s revenue budget in recent years to help pay for day-to-day running costs.

It emerged this week Sheffield Teaching Hospitals NHS trust has had to close four wards, a total of 120 beds, in the Sir Robert Hadfield wing of the Northern general hospital, since last November because the fire brigade deemed the facilities a fire risk and issued a prohibition order.

The Health Service Journal also said two wards in a major trauma unit at Oxford University Hospitals trust have been closed since the Grenfell Tower fire in 2017, over concerns the building’s cladding is inadequate. The 52 beds, however, have been provided elsewhere on-site and the major trauma service is operating as normal.

This month, Boris Johnson promised £1.8bn in extra capital funding for the NHS to fund upgrades at 20 trusts and build new facilities. However, NHS Providers said this could “only be considered a first down payment of the NHS’s needs”. It has a £6bn maintenance backlog, of which £1bn is needed to urgently tackle problems threatening patient safety.

Before next week’s spending review, NHS Providers wants ministers to bring forward a multiyear capital funding settlement and commit to increasing the proportion of GDP spent on health infrastructure from 0.3% to the 0.6%, as is the case in comparable countries.

Since 2017 St Mary’s hospital in London has been affected by floods, electrical issues and drainage problems. It has included a ceiling collapsing in an elderly care ward and maternity services being relocated because of a fault with a lift. In addition, 20 surgical beds and two operating theatres had to close for two weeks owing to flooding and it has been unable to use the 32 beds in its Grafton ward since May 2018 because the floor is too weak to support them.

The archaic nature of much of the estate at Imperial College Healthcare NHS trust, which runs St Mary’s and four other hospitals, means its maintenance backlog would cost £1.3bn to clear.

A Department of Health and Social Care spokesperson said: “We recently gave the NHS an extra £1.8bn of new funding to invest in frontline facilities, including 20 new hospital upgrades across the country.

“We’re also going to be taking a more strategic approach with a new health infrastructure plan that will set the priorities for the NHS over the long term.”

• This article was amended on 30 August 2019 to reflect an amendment to the HSJ article clarifying the status of the major trauma unit at the Oxford University Hospitals trust.