Safety experts compiled report last year that warned an increasing number of buildings are being wrapped in ‘potentially combustible materials’

The government’s building safety experts warned last year that the drive for greater energy efficiency meant more and more buildings are being wrapped in materials that could go up in flames.

In a report compiled before the Grenfell Tower disaster on Wednesday, the Building Research Establishment, which works for the Department of Communities and Local Government on fire investigations, said attempts to innovate with insulation were leading to an “increase in the volume of potentially combustible materials being applied” to buildings.

Construction and fire experts increasingly fear that the cladding system applied to Grenfell Tower may have been instrumental in spreading the fire. The system was installed to improve the thermal efficiency of the building and improve its appearance.

Investigations are also focused on gas pipes in the stairways and lobbies recently installed by National Grid, which residents had complained had not been boxed in with fire retardant material despite assurances they would be.

London's high-rise tenants cite concerns in wake of Grenfell Tower fire Read more

London fire brigade said on Thursday a gas main inside the block had ruptured, causing firefighters to work through Wednesday night to isolate it.

There is also uncertainty over how the project’s adherence with building regulations was scrutinised. The Royal Borough of Kensington and Chelsea, where Grenfell Tower is situated, said a “full plans decision notice was not required in this case” and that “a completion certificate was issued” instead.

According to the government’s website, a full plans decision notice is “the most thorough option”, but this was not taken. Neither the borough nor the cladding contractor, Harley, responded when asked to comment on why this route was not taken.

The Reynobond cladding applied to the Grenfell tower last year as part of a £10m refurbishment is made from powder-coated aluminium panels that are usually filled with plastic insulation, which is flammable.

As detailed on the planning application, fire barriers were due to be inserted between the cladding on each floor to limit the spread to small melt out areas. But Dr Jim Glocking, technical director at the Fire Protection Association, said its own tests on external thermal insulation cladding systems showed that if these barriers are breached by a vent or a pipe, “a chimney effect may quickly develop that will cause the very rapid consumption of the insulation and expansion of the damage area”.

Geoff Wilkinson, managing director of Wilkinson Construction Consultants, said the hole could be relatively modest in size, adding: “Even a drill hole of four inches in diameter can be enough.”

During planning in 2012, the building service engineering company Max Fordham advised that one option in the refurbishment was to remove “fire stopping” systems temporarily in order to install new heating pipes. It is unclear if that approach was taken and Max Fordham did not return request for comment.

The cladding contractor, Harley, declined to comment on how the system was built out – citing the forthcoming investigation and public inquiry. But it is understood the design differed to that which was detailed in planning documents. Investigators are likely to want to quickly establish whether details such as cavity fire barriers, which appeared in planning drawings, were included.

Rydon, the main contractor, said in statement the project “met all required building regulations – as well as fire regulation and health and safety standards – and handover took place when the completion notice was issued by Royal Borough of Kensington and Chelsea building control”.

Rydon chief executive Robert Bond said: “I will do all I can to assist in this investigation in order to establish what caused this tragedy. In light of the public inquiry, we cannot make any further comment at this time.”

Ipswich firm Celotex confirmed it provided insulation materials for the refurbishment. The material has the most stringent “class 0” fire rating in building standards regulations but independent tests on the material used to make it, polyisocyanurate, show that in intense fires it can release lethal hydrogen cyanide fumes and can be rapidly fatal.

Public Health England moved to dampen fears about ongoing poisons in the air and a spokeswoman said there was “minimal wider risk to public health as a result of the smoke plume”. She said all smoke is toxic and could have affected those close to the scene but that no additional or unusual chemical fumes had been detected.

At least one other London tower block has been refurbished using the same Reynobond aluminium cladding system used on Grenfell Tower. A planning application to renovate Clements Court in Hounslow, which has 13 storeys, was made in 2008. Planning application documents filed with the council detail plans to provide the building with a rainproof cladding, using the Reynobond brand of panels.

One architect, who has used similar systems, said cladding panels are also available with mineral wool insulation, which are less flammable but more expensive.

“I only use the mineral wool ones because your gut tells you it is not right to wrap a building in plastic,” he told the Guardian.

As far back as 2000, Gordon Cooke – a leading fire safety consultant – warned in a report commissioned by the mineral wool industry “the use of plastic foam cored sandwich panels ... is difficult to justify when considering life safety”.

He said the panels “can contribute to the severity and speed of fire development” and said this has led to “massive fire loses” in the past.