fidobsa

Most of you will have heard about the tragic tower block fire in London. It seems that one of the causes for the rapid spread of fire was combustion of exterior insulation in cladding panels that were fitted a couple of years ago. I have been planning to get the expanded polystyrene outside insulation fitted to my house but am now having second thoughts. It could be that the coating on the outside of the insulation provides an oxygen barrier but what about the top edge? If it starts to burn at the top edge, the vertical coating layer could form a chimney to take away the smoke and allow further combustion.

Has anyone heard of house fires attributed to or exacerbated by outside insulation?

Peter_in_Hungary

As far as I have heard the problem with the external insulation was that there was a cladding applied on top of the insulation with a gap between the cladding and the insulation. This gap provided the chimney effect which accelerated the burning. The taller the chimney the bigger the effect ! so take that over 24 floors and you have a problem. Without the gap there is no chimney effect and so no problem.

The external insulation used here has a cement based render on the outside which is non-flammable and in any event has no cladding and therefore no chimney effect. The type of external insulation used here has been used in Germany for over 30 years and as far as I know there have been no problems with fire as seen in London (I am sure Germany would have stopped using it after a fire like London experienced).

I would be more concerned about a roof fire than the external insulation catching fire!

mfesharne

I asked the same question of a fire safety surveyor just today & his answer was:

"Yes polystyrene is a problem as it is highly flammable, it should less of a problem externally coupled with render."

Personally, I wouldn't ever have even considered polystyrene & even more so after this recent tragedy.

I might consider the blue foam insulation but would want to be sure it was at least fire resistant before I installed it.

fidobsa

My understanding was that the cladding consisted of metal panels with an insulation coating. I thought it must be something like the box profile roofing sheets that can be supplied with a polyisocyanurate foam coating.

mfesharne

As I understand it the stuff on the tower block had an air gap that acted like a chimney which of course made matters much worse but any polystyrene burns like hell when it gets going.

Don't know if it's true but the media are claiming a fireproof version would only have cost a couple of quid a panel more & if that is true, it's a bloody disgrace

Pulaski

No, it was insulation with a metal (aluminum) coating, and then installed on the building with a separate outer "rain screen" shell. There was a gap between the insulation panels and the outer shell that provided the chimney for the flames to pass up through.

Given that aluminum has a very low melting point, and in any case, when in thin sheet/foil form burns easily to make a sand-like powder, and is strongly exothermic (generates a lot of heat) the "metal" provided no barrier to stop the flammable insulation catching fire.

Pulaski

You have duplicated the content of post #5, above.

FenTiger

Quite a few of my colleagues travelled past Grenfell on the way to work and home. They said the smell was awful.
I've learnt more on here about the cladding than UK news!!!!

FenTiger

Several of my colleagues travelled past Grenfell tower past few days. They said the smell was acrid.
My NHS employers are in the process of setting up a trauma centre to provide counselling.
According to UK media the building control dept from RBKC signed off the works carried out. If anyone is to blame it's them!!!

Pulaski

I would lay the blame on whoever approved the product as suitable/safe for a residential building - the RBKC would have no reason/basis to go against that, AND/OR whoever designed the installation, using a flammable insulation installed with an air gap - neither the installation contractor nor the RBKC would IMO likely have a basis to go against the design engineer.

mrken30

I bet some bean counter asked the question, why are we using the more expensive cladding, lets go for the less expensive option. What are the chances that there will ever be a fire? Share holder value and bonuses.

Pulaski

Maybe indirectly - public works are open to bids, and the cheapest bid that meets the specifications usually wins. So long as the product used is approved for the purpose it is being used, pretty much any product would be accepted - hence my post above blaming whoever approved that product for use on residential buildings.

Chatter Static

Not to mention the person that approved the decompartmentalization of the internal fire safety zones when the interior was updated and then there is the fact that the policy for evacuation was inadequate as people were being told to remain in their flats despite the stairwell being safe to travel down.

chawkins99

I grew up on a council estate in Birmingham that had about 30 high-rise tower blocks. Over the years, I saw several instances of fire in those buildings. None that I recall ever spread beyond the initial unit. The windows would be blown out and the exterior walls black from smoke/flames but never encroached on the neighbouring units.

mrken30

This a a youtube video of a basic flammability test on the material.