Experts’ warning over insulation materials used in V&A Dundee roof.

Experts claim insulation used in Dundee’s flagship museum is easily ignited and gives off toxic gases when on fire

The roof of the V&A Dundee contains flammable insulation that has been linked to the spread of the Glasgow School of Art fire and Grenfell Tower’s windows.

Scotland’s flagship museum last night said it is “fully compliant with all existing building standards”.

Safety experts, firefighters and campaigners have, however, all warned against the use of combustible polyisocyanurate, or PIR, materials on public buildings.

Manufacturer Kingspan’s website boasts of the high levels of energy efficiency provided by its product on the £80 million building but makes no mention of its fire safety performance.

The V&A is fitted with two different types of the roofing product, both made by the company.

In a submission to the Scottish Parliament’s Local Government Committee investigation into fire safety, the Fire Brigades Union questioned the use of PIR in Scotland, adding the material has “unusual burning characteristics”.

It said: “The demands for better and better thermal insulation of buildings is driving innovation in the construction industry, but unfortunately, most of the best insulation materials are also easily ignited and very combustible but there is not the resource any more to study the risk.”

PIR is up to 50% cheaper than nonflammable products stone wool or glass wool, which are made from recycled glass and strands of rock.

It also gives off toxic gases, including hydrogen cyanide and carbon monoxide, when ignited.

The material is rigid plastic foam between two sheets of aluminium foil. The foil is designed to stop the flammable insulation catching fire.

It has been reported that PIR was used on the Glasgow School of Art.

Firefighters are investigating whether it aided the spread of the June 16 blaze.

The material meets building regulations standards but both types used on the V&A are categorised as Euroclass E for fire safety, the second lowest rating possible.

In its Scottish Governmentcommissioned report, the Review Panel on Building Standards (Fire Safety) in Scotland recommended external walls of all “entertainment and assembly buildings” are fitted with material that meets at least a Euroclass A2 rating.

That is four notches above the V&A roof insulation’s rating, although the document does not make any specific recommendations about roof spaces.

Industry sources said the biggest potential for any fire starting on a roof would be when remedial works take place. One source said: “Why would you consider putting non-combustible facades on and not carry on to the roof?”

The V&A said no welding will take place on its roof.

Class E is the same rating as the window insulation in Grenfell Tower.

In evidence to the Grenfell inquiry experts blamed such insulation for helping spread the fire.

Charlie Sadler, a fire safety expert and a core member of the Grenfell fire forum, said no combustible material should be used on any building that is three storeys or higher.

Ms Sadler, who has more than 26 years’ experience working in structural fire protection, said: “PIR will get round tests by putting foil round it.

“It’s like if you put a naked flame to your turkey at Christmas it will burn to a crisp but if you put foil round it, it will cook nicely.

“The problem is when the foil goes it will ignite very easily and won’t stop.

“What happens if you have a fire on the top storey of a building? The first place it will go is the roof.”

She added: “To make it as thermally efficient as possible, it (PIR) is the better, easier, and cheaper route.”

Joe Delaney, of the Grenfell Action Group, said: “This stuff shouldn’t be used on any building, regardless of what the building may be.

“I don’t care if it’s a museum or a school, or a hospital, or a home.

“It’s not worth the chance, even if there is a one-in-a-million chance that this could happen, that is still too much.”