Huge Fire In Block Of Flats

[V8 Fettler]

skwdenyer said:

I think the essential point still stands; without the cladding there would have been no problem, it seems.

The works made the building less safe in 2017 than it was when built 40+ years earlier.

That that should even be possible is the one overarching issue; everything else is really semantics.

Good design would ensure that this doesn't occur, the starting point being to identify the fire resistance of the concrete exterior of the building prior to the refurbishment works.

[FurtiveFreddy]

Digga said:

Aluminium is very reactive, it's just that under normal conditions, it develops an oxide layer (hence why when you cut/gouge aluminium it looks shinier) and is stable.

My FIL is an insurance risk assessor and told me about a serious explosion where a firm had been cutting/grinding aluminium and then a spark hit a large pile of the dust. Two fatalities.

Yes, but there's a big difference between metal sheet/foil and metal particles/dust and how they ozidize.

You can set fire to steel wool with a 9V battery, but try burning a sheet of it.

You need a lot of surface area before metals such as aluminium will oxidise fast enough to keep a fire going. My own view is that the aluminium sheet may not turn out to be the critical element in all of this.

What needs to happen (and I'm assuming there is someone already planning to do this) is to remove the undamaged sections of the cladding and refit it exactly as it was originally onto a test rig so it can be set alight and studied properly.

[saaby93]

FurtiveFreddy said:

What needs to happen (and I'm assuming there is someone already planning to do this) is to remove the undamaged sections of the cladding and refit it exactly as it was originally onto a test rig so it can be set alight and studied properly.

There's a large test rig that's recently become available

[Vipers]

saaby93 said:

FurtiveFreddy said:

What needs to happen (and I'm assuming there is someone already planning to do this) is to remove the undamaged sections of the cladding and refit it exactly as it was originally onto a test rig so it can be set alight and studied properly.

There's a large test rig that's recently become available

They did just that after a night club fire in Ireland many moons ago.

The fire brigade couldn't work out how the fire spread so quickly. A test rig was set up consisting of a replica of part of the night club, can't remember the results but it did demonstrate why it spread so fast. So guess they will do something similar.

Just googled, this is it, https://en.m.wikipedia.org/wiki/Stardust_fire

Edited by Vipers on Tuesday 20th June 19:41

Edited by Vipers on Tuesday 20th June 19:42

[Elysium]

V8 Fettler said:

skwdenyer said:

I think the essential point still stands; without the cladding there would have been no problem, it seems.

The works made the building less safe in 2017 than it was when built 40+ years earlier.

That that should even be possible is the one overarching issue; everything else is really semantics.

Good design would ensure that this doesn't occur, the starting point being to identify the fire resistance of the concrete exterior of the building prior to the refurbishment works.

No, there are other options. We don't all live and work in concrete faced structures. Spread of flame on exterior facades needs to be controlled, but this should not ever be critical for life safety.

[gareth_r]

Digga said:

Aluminium is very reactive, it's just that under normal conditions, it develops an oxide layer (hence why when you cut/gouge aluminium it looks shinier) and is stable.

My FIL is an insurance risk assessor and told me about a serious explosion where a firm had been cutting/grinding aluminium and then a spark hit a large pile of the dust. Two fatalities.

Surprising substances can explode when in powder form - flour, for example. Anything combustible, in fact.

[V8 Fettler]

Elysium said:

V8 Fettler said:

skwdenyer said:

I think the essential point still stands; without the cladding there would have been no problem, it seems.

The works made the building less safe in 2017 than it was when built 40+ years earlier.

That that should even be possible is the one overarching issue; everything else is really semantics.

Good design would ensure that this doesn't occur, the starting point being to identify the fire resistance of the concrete exterior of the building prior to the refurbishment works.

No, there are other options. We don't all live and work in concrete faced structures. Spread of flame on exterior facades needs to be controlled, but this should not ever be critical for life safety.

The concept of cladding Grenfell Tower in a material that has a lower fire resistance than the concrete exterior of the unrefurbished tower is demonstrably flawed.

[Elysium]

V8 Fettler said:

Elysium said:

V8 Fettler said:

skwdenyer said:

I think the essential point still stands; without the cladding there would have been no problem, it seems.

The works made the building less safe in 2017 than it was when built 40+ years earlier.

That that should even be possible is the one overarching issue; everything else is really semantics.

Good design would ensure that this doesn't occur, the starting point being to identify the fire resistance of the concrete exterior of the building prior to the refurbishment works.

No, there are other options. We don't all live and work in concrete faced structures. Spread of flame on exterior facades needs to be controlled, but this should not ever be critical for life safety.

The concept of cladding Grenfell Tower in a material that has a lower fire resistance than the concrete exterior of the unrefurbished tower is demonstrably flawed.

I think you are jumping to conclusions. concrete is non combustible. Regulations allow overcladding with material of limited combustibility. That should not have any impact on the safety of occupants. Their safety can be protected in many other ways and that should have happened here.

[V8 Fettler]

Elysium said:

V8 Fettler said:

Elysium said:

V8 Fettler said:

skwdenyer said:

I think the essential point still stands; without the cladding there would have been no problem, it seems.

The works made the building less safe in 2017 than it was when built 40+ years earlier.

That that should even be possible is the one overarching issue; everything else is really semantics.

Good design would ensure that this doesn't occur, the starting point being to identify the fire resistance of the concrete exterior of the building prior to the refurbishment works.

No, there are other options. We don't all live and work in concrete faced structures. Spread of flame on exterior facades needs to be controlled, but this should not ever be critical for life safety.

The concept of cladding Grenfell Tower in a material that has a lower fire resistance than the concrete exterior of the unrefurbished tower is demonstrably flawed.

I think you are jumping to conclusions. concrete is non combustible. Regulations allow overcladding with material of limited combustibility. That should not have any impact on the safety of occupants. Their safety can be protected in many other ways and that should have happened here.

The regulations are demonstrably flawed. Difficult writing a risk assessment for a design solution that increases risk.

[///ajd]

FurtiveFreddy said:

Yes, but there's a big difference between metal sheet/foil and metal particles/dust and how they ozidize.

You can set fire to steel wool with a 9V battery, but try burning a sheet of it.

You need a lot of surface area before metals such as aluminium will oxidise fast enough to keep a fire going. My own view is that the aluminium sheet may not turn out to be the critical element in all of this.

What needs to happen (and I'm assuming there is someone already planning to do this) is to remove the undamaged sections of the cladding and refit it exactly as it was originally onto a test rig so it can be set alight and studied properly.

Agreed. I suspect the issue may be that the fire test of the panel is not representative enough of the actual installation or the flame it will be actually subjected to.

Testing an Alu PE panel with a flame for a period might be OK up to a point, and a panel could 'just' pass. If when it fails it spews out molten PE that immediately turns into a raging fire, then passing that test looks a bit "not the whole story".

I have read that some demand more representative tests - i.e. they should be torching the panels when in a representative installation, with wind factors and a fire immersing the panel as it would from a window.

Kapton wiring was great in many tests and had great properties - until they realised what the longer term poor qualities were (after several aircraft crashes).

[Elysium]

V8 Fettler said:

The regulations are demonstrably flawed. Difficult writing a risk assessment for a design solution that increases risk.

It is far too soon to conclude that.

[Wiccan of Darkness]

Elysium said:

If this is accurate, then it is absolutely shocking. ACM materials are in widespread use in buildings. Whilst I have been cynical about the 'limited combustibility' claims made by manufacturers, I would never have even considered the possibility that ACM might in fact be 'highly combustible'. I think very few people would.

This document looks at the testing for the insulation used at Grenfell:

https://www.celotex.co.uk/assets/rainscreen-compli...

The tests were carried out with a fibre cement panel, not aluminium rainscreen. So the note on page 4 may be quite significant:

"The fire performance and classification report issued only relates to the components detailed and constructed in figure 4. Any changes to the components listed and construction method set out in figure 4 will need to be considered by the building designer."

Sorry to be a PITA but as I know absolutely nothing about construction as per se, what is/are ACM materials?

As for the basic chemistry, it's the nuts and bolts of my world. I wouldn't expect an architect, who knows about designing buildings, the forces, loads and physics as well as the aesthetics to know the complex chemistry behind the materials, I would have hoped that during the design stage of the panels themselves, a materials scientist would have tested the things and said whoa there matey.

My gut feeling is each component was tested, so they know aluminium sheet doesn't catch fire easily, plastic just melts, etc etc . Nobody bothered to look at the finished article.

[Olf]

It's all about context and application. These panels are fine when there's 1 of them, 10 of them, 50 of them but not when there's 1,000 of them all lined up ready to go.

Here'a really good piece I found last week about the panels straight after the fire:

http://www.probyn-miers.com/perspective/2016/02/fi...

We learned in 1982 in the Falklands how well aluminium alloys burn/support fire in the right conditions. A lesson we're going to have to learn all over again sadly.

[Elysium]

Wiccan of Darkness said:

Elysium said:

If this is accurate, then it is absolutely shocking. ACM materials are in widespread use in buildings. Whilst I have been cynical about the 'limited combustibility' claims made by manufacturers, I would never have even considered the possibility that ACM might in fact be 'highly combustible'. I think very few people would.

This document looks at the testing for the insulation used at Grenfell:

https://www.celotex.co.uk/assets/rainscreen-compli...

The tests were carried out with a fibre cement panel, not aluminium rainscreen. So the note on page 4 may be quite significant:

"The fire performance and classification report issued only relates to the components detailed and constructed in figure 4. Any changes to the components listed and construction method set out in figure 4 will need to be considered by the building designer."

Sorry to be a PITA but as I know absolutely nothing about construction as per se, what is/are ACM materials?

As for the basic chemistry, it's the nuts and bolts of my world. I wouldn't expect an architect, who knows about designing buildings, the forces, loads and physics as well as the aesthetics to know the complex chemistry behind the materials, I would have hoped that during the design stage of the panels themselves, a materials scientist would have tested the things and said whoa there matey.

My gut feeling is each component was tested, so they know aluminium sheet doesn't catch fire easily, plastic just melts, etc etc . Nobody bothered to look at the finished article.

ACM = aluminium composite material = the rainscreen panel = PE insulation sandwiched between aluminium coil.

The issue here is that the manufacturers of the insulation and the rainscreen panel claim to have tested them, to the relevant BS and to a specific standard developed by the BRE.

The celotex insulation was tested as a component in a rain screen cladding system, but with a glass reinforced concrete panel. I have not been able to find any details of the testing carried out on the ACM, but it is claimed to have fire resisting properties.

I don't know if anyone has tested this specific insulation and ACM together.

There is also the complication of the installation method and cavity fire protection, which we don't have details of.

In any event manufacturers have developed these materials as products, tested them and marketed them.

[Willy Nilly]

Regardless of who or what is to blame, a week on and people will be starting to realise what a massive pain in the arse it is to have your house burn down. Because there are so many people involved, it's going to be a nightmare to get them housed and the poor buggers are likely to be moved from hotel to hotel. Never mind loosing stuff like your keys, bank cards and all your paperwork to say who you are.

[julianm]

Shuttle rocket boosters use powdered aluminium, not aluminium oxide. It is the oxidation of the aluminium which provides the high temp/expansion to give the boost.
https://www.nasa.gov/returntoflight/system/system_...

[///ajd]

When you look at some photos it looks like the insulation has sometimes not burnt when the whole Alu panel is missing (i.e. it fell off before the class 0 insulation caught fire) and in some cases it looks like charred / cracked PE is left stuck to the inner of the 2 alu coil panels.



It could even be just the panel that is the issue. Fine for being heated for 15 mins or so, the catastrophically goes up beyond say 20 mins. If the fire that is touching the panle lasts longer than that - its curtains - and the panel sets off a fire in the next apartment, and then the next panel - and so on.

It even looks like the panel burnt (and went out) relatively quickly leaving the fire to rage in the apartments (hence later on only having the fire visible inside the windows, whilst the cladding area was black).

[///ajd]

Olf said:

It's all about context and application. These panels are fine when there's 1 of them, 10 of them, 50 of them but not when there's 1,000 of them all lined up ready to go.

Here'a really good piece I found last week about the panels straight after the fire:

http://www.probyn-miers.com/perspective/2016/02/fi...

We learned in 1982 in the Falklands how well aluminium alloys burn/support fire in the right conditions. A lesson we're going to have to learn all over again sadly.

That report is damning, especially para 8.

The risks were well known to some. Such a risk would be easy grounds for an Airworthiness Directive to remedy on a aircraft - change it within X months or no flying.

[Elysium]

///ajd said:

Olf said:

It's all about context and application. These panels are fine when there's 1 of them, 10 of them, 50 of them but not when there's 1,000 of them all lined up ready to go.

Here'a really good piece I found last week about the panels straight after the fire:

http://www.probyn-miers.com/perspective/2016/02/fi...

We learned in 1982 in the Falklands how well aluminium alloys burn/support fire in the right conditions. A lesson we're going to have to learn all over again sadly.

That report is damning, especially para 8.

The risks were well known to some. Such a risk would be easy grounds for an Airworthiness Directive to remedy on a aircraft - change it within X months or no flying.

If you read it carefully, you will note that the improved testing standards it recommends are the ones used by celotex to test the rs5000 material used at grenfell tower (BS and BRE)

It also notes U.K. Regulations are stricter than other regions on fire breaks in cavities and the conclusion seems to be that most of the 'problem' buildings will be outside of the UK.

Its easy to use hindsight to suggest that people must have been aware that this cladding was dangerous, but I am not at all sure that was the case.

It's still not clear why this fire was so severe. The type of cladding may be to blame, or it may have been incorrectly installed, or it may be due to other factors.

The pictures above of the damaged building show celotex panels charred but apparently intact. The outer ACM rainscreen appears to have been destroyed. We don't know yet if it was destroyed because the fire was so severe, or it it caused the fire to be severe.

[b0rk]

Elysium said:

This is the brochure for the product used. Both the PE (combustible blown foam) and FR (non-combustible rockwool) panels have the same class A rating for spread of flame

The small problem is the "class A" is to the US ASTM standard which isn't accepted under document B where only BS 476-6/7 or BS EN 13501-1 are acceptable, btw the European data for the FR product lists the combustibility as B-s1,d0 and PE as B-s2, d0. These would on the surface be compliant with diagram 40 of approved document B2.

However as the construction contained a cavity and the insulation was not non combustible then the clauses around BS8414 / BRE135 for the complete system come into effect. You can't strictly speaking in compliance with the building regs combine an insulation of limited combustibility and a cladding of limited combustibility and assume because both individually are acceptable that once combined they remain acceptable. In simple terms 2+2 many not equal 4.

I've through work organised a few BS8414 tests at the BRE and can't really see how the construction used would gain an acceptable result under BRE135 based on the fire spread restrictions and cavity barrier bypass. Requirement 2 of BRE135 is IIRC that the temperature must not reach 600°C 1m above fire floor within the first 30 minutes. Requirement 1 is all around loss of compartmentation (fire spread) limited to no more than 2.5m in 15 minutes...both from the pictures appear to have failed in practice on the building.

One of the issues with BRE 135 is the possibility of commissioning a desktop study in place of doing the very expensive BS8414 test where a untested cladding, insulation or cavity barrier is assessed on the basis of similarity to a tested one. It isn't to me outside the bounds of possibility that the "limited combustibility" of the Reynobond PE ACM has been assumed to similar to the "limited combustibility" of say a Zinc or Aluminium honeycombe panel and an assessment written accordingly justifying the suitability.

The problem with class 0 limited combustibility as a concept is that such a wide variety of stuff is lumped under it and a product made of multiple materials doesn't need to be of limited combustibility throughout to pass the test criteria.