At least one housing estate built using reinforced autoclaved aerated concrete (RAAC) is still in use, openDemocracy has discovered, as the government indicates it will not pay for any improvement works on residential buildings despite emerging fears over the material.

There is no suggestion residents are at immediate risk, but the revelation will add to pressure on ministers to act to avoid what one campaigner has called a potential “cladding-style scandal in the making”.

openDemocracy has chosen not to identify the estate, in Essex, until the local council has made contact with tenants and building owners.

Update: ‘We’ve been told nothing’, say families on Essex estate built using RAAC

Fears over the material, primarily used to construct public buildings between 1960 and 1980, have sparked the closure of more than 100 schools after a ceiling fell in at a primary school in 2018 and a roof beam collapsed this summer. No children were harmed.

Despite the known risks of RAAC degrading in buildings more than 30 years old, the Department of Levelling Up, Housing and Communities’ (DLUHC) position is that building owners are responsible for ensuring buildings are safe – a contrast from the government’s policy on dangerous cladding, which saw it cough up £5.1bn to help remove the material from buildings over a certain height.

MPs have raised issues with residential buildings built with RAAC, also known as Siporex, in the past.

The late David Amess spoke often on issues facing his constituents on an estate in Basildon in the 1980s and 1990s.

Speaking in Parliament about the scandal-hit Laindon 1, 2 and 3 “Siporex estate” in Basildon, Essex, he said: “There have been problems with ceilings, windows and general dampness,” and that the material “cracks as one walks on it, and now most properties must have the entire first floor replaced.” The buildings were finally demolished in 1994. Siporex was a brand name for RAAC and first produced in the UK by Costain Concrete Co Ltd, which opened its plant in Lanarkshire, Scotland in the early 1960s.

openDemocracy has now identified another, smaller, residential estate built with RAAC that is still occupied. Initially council housing, some of it now appears to have been sold off into the private sector. Given the material’s prevalence in the mid-20th century, it is likely to be the first of a number that emerge as containing the bubbly concrete, which is vulnerable to weakening and collapse.

In December 2018, after the incident at a primary school in Gravesend, an email was sent out to all local councils from the Department for Education and the Local Government Association asking local authorities – who own and manage social housing as well as schools – to check for all properties in their portfolio constructed using RAAC.

In the email seen by openDemocracy, both bodies suggested that councils should “identify any properties constructed using Reinforced Autoclaved Aerated Concrete (RAAC) and validate the potential risk appropriately,” and “consider and monitor the possible impact of reduced maintenance regimes on the condition of your property portfolio, in particular where RAAC is used”.

The question of who picks up the bill for remediation works could prove problematic, said Greg Carter, a legal director specialising in construction and insurance disputes at Winckworth Sherwood.

“The big thing is that owners only have 30 years to make claims under the Defective Premises Act so buildings built pre-1990 are not going to get the benefit of that,” he said.

“In my view building owners need to check their building insurance policies now to see if RAAC is covered because you may find that policy has changed next year and insurers have removed RAAC cover. The race is on.”

The scale of the RAAC crisis in the UK is compounded by the little information held by public bodies on its prevalence in the public or private sector. DLUHC could not say whether it held any information on how many social housing blocks still occupied were built using RAAC, and no public register exists.

The aerated material, popular for its affordability, is mainly used in ceilings but can also be found in walls and floors and is easily susceptible to water damage. An advert from Siporex calls it a “remarkable, lightweight, aerated concrete”.

Suzanne Muna, secretary of the Social Housing Action Campaign (SHAC), warned it could be a “cladding-style scandal in the making,” and said members had been raising concerns as to whether they could be affected by the degrading building material.

“While it may be true that RAAC is not present in many buildings, where it is present, it can pose a very serious risk of harm,” Muna told openDemocracy. “Damp for example makes this already weak concrete deteriorate further, and far too many housing association homes are still riddled with damp and mould problems. If a ceiling or wall collapses, it can be fatal.

“The way that the sector failed to manage the cladding scandal effectively has left many tenants and residents without any trust or confidence in their landlord’s integrity.

“We’re calling on the sector to break its previous track record and take some leadership on this.

“They need to check the construction of all their properties, promptly let tenants and residents know if RAAC is present or not, and – if it has been used – immediately put into place a plan to make it safe as soon as it can be done.”

The Regulator for Social Housing has today written to providers in England calling on them to check for RAAC in their buildings. It said it does not believe RAAC is “widespread” in social housing but “it may be present in a small number of buildings dating from this period”.

Housing campaigner Kwajo Tweneboa told openDemocracy: “Although we are being told RAAC isn’t a widespread issue within housing, I think it’s too early to say that.

“So many social homes that were built between the 1960s and 1980s are still standing. If the homes people are going to sleep in at night are at risk of caving in because RAAC has been used in the past, the public need to know. You would’ve thought this issue of ‘building safety’ would’ve been a primary concern, especially after Grenfell.”