Grenfell Tower fire

[Temp]

Perhaps I'm wrong but I thought the Met/Scotland Yard statement implied that the samples failed a standard flammability test - not a test carried out to simulate the conditions at Grenfell. She talked about the insulation failing the test and also the tiles failing the test. 

 

 

[Jeremy Harris]

It's not clear what the tests were, but I'd guess that they were combustibility tests, not flammability or fire resistance tests.  A significant part of this problem seems to be the way that fire resistant materials are classified and tested here.  Building regs seem focussed on the surface spread of fire, with the intention being to limit how quickly a fire can spread from one dwelling to another.

 

There's been a lot of focus on the aluminium composite cladding, but it has better German and French fire ratings than the underlying PIR foam.  The PE core Reynobond has a German DIN 4102 rating of B2, and a French NF P 92-501 rating of M1, essentially it's rated as being combustible but non-inflammable.

 

By contrast, PIR foam is combustible, and has a poorer fire rating than the aluminium composite cladding, so it seems most likely that the breakdown of the PIR was the major source of fuel for the fire, until it reached a high enough temperature to burn through the alloy skin of the cladding panels, allowing the PE core to burn as well.  I strongly suspect that the temperatures inside the ventilation cavity were high enough to ignite the aluminium alloy of the cladding panels, too, as there seems to be less debris on the ground around the tower than might be expected if the aluminium cladding just fell off (it seems clear that there is no cladding left on the burned sections of the tower).

 

 

[Ferdinand]

I am interested why Camden felt it necessary to wake up and evacuate 700 families overnight.

 

Given that the cladding had been on these blocks for a decade I do not think that waiting until Saturday AM after a take care warning would be a significant extra risk.

 

Virtue Signalling or getting in first?

 

Ferdinand, being a little cynical.

[Jeremy Harris]

Getting in first, I'm sure.  More of a political point than a measured response to the real risk, especially as their tower blocks have non-combustible rockwool insulation, AFAICS. 

 

Why didn't they take the more sensible option of appointing 24 hour fire wardens to reduce the risk to an acceptable level?

[SteamyTea]

1 hour ago, JSHarris said:

essentially it's rated as being combustible but non-inflammable.

combustible

kəmˈbʌstɪb(ə)l/

adjective

adjective: combustible

1. 1.

   able to catch fire and burn easily.

   "a combustible gas"

inflammable

ɪnˈflaməb(ə)l/

adjective

adjective: inflammable

1. 1.

   easily set on fire.

   "inflammable materials"

flammable

ˈflaməb(ə)l/

adjective

adjective: flammable

1. easily set on fire.

   "the use of highly flammable materials"

Aluminium combustion temperature: 600-650°C

[Jeremy Harris]

Just quoting the wording on the certification!

 

The various test and certification bodies for building materials do seem to make distinctions between flammability, combustibility and fire resistance, and they seem to vary from one country to another, even within Europe.  Ours are perhaps the weakest, as the main concern until now seems to have been the surface spread of fire rating, and that seems to be flawed when materials are combined in the way they were with the Grenfell Tower refurbishment.

 

38 minutes ago, SteamyTea said:

Aluminium combustion temperature: 600-650°C

 

That's around the melting point (typically about 660 deg C - source Kaye and Laby), rather than the combustion temperature, and aluminium doesn't truly burn, as such.  I believe the main aluminium risk may be from the combination of high temperature and water, or water vapour, which will cause an exothermic reaction and release hydrogen to fuel any fire.  It may well be that the higher intensity fire just above the point where one of the platform firefighters is directing water is a consequence of this reaction (this is based on the video clip linked to earlier).

Edited June 24, 2017 by JSHarris

[Ferdinand]

19 minutes ago, JSHarris said:

Just quoting the wording on the certification!

 

The various test and certification bodies for building materials do seem to make distinctions between flammability, combustibility and fire resistance, and they seem to vary from one country to another, even within Europe.  Ours are perhaps the weakest, as the main concern until now seems to have been the surface spread of fire rating, and that seems to be flawed when materials are combined in the way they were with the Grenfell Tower refurbishment.

 

 

That's around the melting point (typically about 660 deg C - source Kaye and Laby), rather than the combustion temperature, and aluminium doesn't truly burn, as such.  I believe the main aluminium risk may be from the combination of high temperature and water, or water vapour, which will cause an exothermic reaction and release hydrogen to fuel any fire.  It may well be that the higher intensity fire just above the point where one of the platform firefighters is directing water is a consequence of this reaction (this is based on the video clip linked to earlier).

 

Aluminium burns in small particles I believe.

 

I read somewhere about such being in some insulation. Here?

[Jeremy Harris]

26 minutes ago, Ferdinand said:

 

Aluminium burns in small particles I believe.

 

I read somewhere about such being in some insulation. Here?

 

Yes, sort of, with an oxidiser present.  The SRBs on the Shuttle used powered aluminium as a component of the fuel, and powdered aluminium is also used in some types of thermite.  To get the aluminium to react there needs to be something present that will act as an oxidising agent.  In the case of the Shuttle SRBs, the oxidising agent was ammonium perchlorate, and the reaction with the aluminium fuel generates a lot of heat, aluminium oxide, aluminium chloride, nitrogen and water vapour.  The reaction occurs at around 3,200 deg C.

 

 

 

[Jeremy Harris]

There seem to be a lot of claims that the rain screen cladding is "banned" in the USA and Europe, which seems a bit odd, as I can't find any evidence to support this.  What I have found is this document that lists the certification for Reynobond in several different countries: https://www.arconic.com/aap/europe/pdf/Certifications page_042014.pdf

 

 

 

 

[Ferdinand]

Just for further info, here is what seems to be the final PA relating to the cladding in 2015. Relating to discharge of a Planning Condition.

 

References Al panels, not Zi.

 

PA

 

https://www.rbkc.gov.uk/planning/searches/details.aspx?adv=0&simple=Grenfell+Tower&simpleBatch=20&simSubmit=Search&id=CON/15/01274&cn=188293+IBI+Group+Chadsworth+House+Wilmslow+Road+&type=decision&tab=tabs-planning-2#tabs-planning-1

 

Schedule of Materials

https://www.rbkc.gov.uk/idoxWAM/doc/Other-1421792.pdf?extension=.pdf&id=1421792&location=VOLUME2&contentType=application/pdf&pageCount=1

 

Pics of Materials

https://www.rbkc.gov.uk/idoxWAM/doc/Revised Drawing-1451739.pdf?extension=.pdf&id=1451739&location=VOLUME2&contentType=application/pdf&pageCount=1

 

Covering Letter

https://www.rbkc.gov.uk/idoxWAM/doc/Other-1421793.pdf?extension=.pdf&id=1421793&location=VOLUME2&contentType=application/pdf&pageCount=1

 

Approval Notice

https://www.rbkc.gov.uk/idoxWAM/doc/Decision-1454972.pdf?extension=.pdf&id=1454972&location=VOLUME2&contentType=application/pdf&pageCount=1

 

They will not imo get the insulation company unless yhey go for the KCTMO and perhaps the Officers as well.

 

F

 

[Jeremy Harris]

I know this is from the Telegraph, but it still seems to indicate that, at long last, the combination of combustible insulation with the chimney effect created by the rain screen cladding and the ventilation gap is being seriously looked at:

 

http://www.telegraph.co.uk/news/2017/06/24/insulation-real-inferno-threat-warn-safety-experts/

 

http://www.telegraph.co.uk/news/2017/06/24/grenfells-unusual-design-led-blaze-spread-say-investigators/

 

Also interesting to see that the media have picked up on the external deluge sprinkler system as risk mitigation - a system that was devised some years ago to deal with this very risk.

Edited June 25, 2017 by JSHarris

[Temp]

https://www.celotex.co.uk/

 

Update - Friday 23rd June

Grenfell Tower: Celotex is to stop the supply of RS5000 for use in rainscreen cladding systems in buildings over 18m tall.

Continues..

 

 

 

[ProDave]

I see from the news that so far 100% of the buildings tested have failed the fire tests There are 600 buildings identified to be tested.

 

Once isolated case of the wrong insulation being used on 1 tower I cuuld understand as negligence or criminal. But it is now beginning to look as though none of these insulated cladding systems are going to pass the tests?

 

Is this a case of the regulations have been tightened since they were originally fitted, or has the whole industry been ignoring the law for some time?

 

This story is going to get bigger and bigger (and very expensive for someone, probably the tax payer)

[Jeremy Harris]

The news seems very far from being accurate, in my view, because there are indications that buildings fitted with non-combustible insulation are being declared as having "failed", and I very strongly suspect there is a degree of sensationalist reporting going on.

 

I believe that it is the aluminium composite cladding that is being tested at the moment, and I frankly doubt that there is anywhere near enough fuel in the 3 to 5mm thick PE core of that to create the sort of fire intensity that we saw on Grenfell Tower.

 

There are more reliable reports that the PIR insulation fitted to Grenfell Tower was the primary fuel source for the fire, and I suspect that, in the final analysis, this emphasis on the composite cladding being the primary cause of the fire will be shown to be wrong.

 

I fear that we have a situation where there are a number of "headless chickens" running around, trying to do a PR job but not having a full understanding of the way the various elements of the insulation, ventilation cavity, fire stopping and external composite cladding, interacted to produce the devastation to this building.

 

My own view is that this may well have been prevented just by having an effective fire stop around the openings.  Looking at the detail drawings, there doesn't appear to have been anything more that a trim around the openings, which seems to be no thicker than the cladding.  I find it hard to see how this thin barrier could have been very effective, and there looks to have been enough of a gap for fire, coming from the window, to penetrate the ventilation cavity, heat the PIR up and cause enough off-gassing to produce the initial fuel for the external fire.  The composite aluminium cladding contributed to the fire, but I doubt it was a big enough fuel source on its own to have caused a major fire.

 

Drawing-1377464.pdf

Edited June 26, 2017 by JSHarris

[Temp]

2 hours ago, JSHarris said:

  Looking at the detail drawings, there doesn't appear to have been anything more that a trim around the openings, which seems to be no thicker than the cladding.  I find it hard to see how this thin barrier could have been very effective, and there looks to have been enough of a gap for fire, coming from the window, to penetrate the ventilation cavity,

 

I thought the cladding panels hooked onto frames that were open in the middle (like a picture frame without glass) so there might be an unobstructed path which I marked in green...

 

[jack]

I assume the gap is there because there's no point having a ventilated rainscreen without ventilation. How to you ventilate such a void without providing a path for fire? Intumescent horizontal fire barriers?

[jamiehamy]

I see John McDonnell made a helpful pronouncement from Glastonbury that the deaths were murder.  For a variety of reasons that man is a moron. 

[Onoff]

1 hour ago, jack said:

I assume the gap is there because there's no point having a ventilated rainscreen without ventilation. How to you ventilate such a void without providing a path for fire? Intumescent horizontal fire barriers?

 

Weep holes at the front maybe and don't have the rear gap?

[Jeremy Harris]

4 hours ago, Temp said:

 

I thought the cladding panels hooked onto frames that were open in the middle (like a picture frame without glass) so there might be an unobstructed path which I marked in green...

 

 

 

That's exactly how I think the fire got up from the window opening into the ventilated cavity.  The installation spec for RS5000 gives a requirement for a rockwool/fibre cement board horizontal fire stop, and that doesn't seem to have been included.

 

4 hours ago, jack said:

I assume the gap is there because there's no point having a ventilated rainscreen without ventilation. How to you ventilate such a void without providing a path for fire? Intumescent horizontal fire barriers?

 

Normally the ventilation should be provided well away from openings in the building that fire might escape from, so typically gaps with insect mesh behind away from the opening, hidden behind the gaps between the cladding cassettes.

 

3 hours ago, jamiehamy said:

I see John McDonnell made a helpful pronouncement from Glastonbury that the deaths were murder.  For a variety of reasons that man is a moron. 

 

He is a moron, and simply has no concept of mens rea, something that I find absolutely gobsmacking given the length of time that he's been in parliament, revising and voting on laws.  The most serious criminal charge that can be brought in this case is gross negligence manslaughter, as they cannot possibly be a valid argument to support actus reus non facit reum nisi mens sit rea.

 

 

Edited June 26, 2017 by JSHarris

[Ferdinand]

I was hearing reports on R4 earlier that the reasons for 100% failure so far (60 out of 60) were because the "flammability" tests were being applied to the foam core element of the cladding panel, not to the full sandwich as applied to the building.

 

If that is the case, and the previous testing regime is deemed to be faulty (rather than faultily applied), they will have a difficult job prosecuting anyone.

[Temp]

I think that's right. I was trying to rationalise all the failures with assertions from the manufacturers that their products meet Building Regs and safety standards.

 

 It seems that the BRE are testing samples using a new/different test method to that used when materials were originally given their fire ratings. The BRE web site statement dated the 21st June says...

 

http://bregroup.com/press-releases/statement-on-grenfell-tower/

 

An immediate area of support we will be giving to Department of Communities and Local Government is to fire test samples of cladding from other high rise buildings for asset owners and operators who may have concerns.

We have developed a test protocol for this work and are currently validating it.

 

That implies this is something new rather than an established test protocol.

 

The Times today also says...

 

Some organisations are taking preventative measures after

it came to light that some materials pass building regulations even though they fail the latest emergency tests.

 

Again suggesting that these are new/different tests.

 

 

[Jeremy Harris]

The lunatics at DCLG have instructed local authorities to cut out (!) 250mm square sections of cladding for testing.

 

This is madness, pure and simple, as cutting sections out will expose the core (which is normally fire-sealed at the edges!), plus the fire testing has to be representative, as a large part of the fire resistance of aluminium comes from its ability to conduct heat away rapidly from a heated area.  This is critically dependent on the ratio of the panel size to the heat source - something that will be massively off with a small sample.

 

They should be testing these panels to a recognised and appropriate test method for cladding material, something like DIN4102, and definitely not BS476, as that doesn't realistically test combustibility in this scenario, in my view.

Edited June 26, 2017 by JSHarris

[ProDave]

An interesting twist to this saga.

 

There was a cladding fire on a high rise in Scotland in 1999. Following that there was an enquiry, and the result was the building regulations were changed with the new regulations coming into force in 2005.  As a result, no high rise buildings in Scotland are thought to be at risk.

 

I wonder if the enquiry in England will ask why was this information not shared (perhaps it was?) and why were English building regulations not similarly tightened?

[Jeremy Harris]

2 minutes ago, ProDave said:

I wonder if the enquiry in England will ask why was this information not shared (perhaps it was?) and why were English building regulations not similarly tightened?

 

I think the answer to that will be the same as the reason for the building regs not taking account of all the external insulation facade fires that have been happening all over the world for the past 10 years or more - commercial pressure against any tightening of the regulations.

 

We saw this with Part L1a, where the initial draft consultation significantly increased the energy performance requirements.  Once there had been consultation with industry, these were significantly watered down, on the basis that there would be cost implications for the construction industry at a time when it was trying to recover from the economic down turn.

 

Never underestimate the ability of commercial interests to buy off government, I've seen it happen first hand, and it's not usually beneficial to taxpayers.

[ADLIan]

Appr Doc B2 already covers the issues faced at Grenfell Tower. Not sure if it's lack of understanding or enforcement is the issue. Cannot copy from the AD but see Section 12 on External walls, in particular paras 12.5 and 12.7. Perhaps these particular statements need emphasising more - capitals, in bold & underlined!!

 

Ian