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no I think the cladding is; outer metal.... middle insulation.. inner something else but not zinc/alloy
no I think the cladding is; outer metal.... middle insulation.. inner something else but not zinc/alloy
The product in question - Arconic Reynobond, is sold in two variants - "PE" and "FR". The list price difference is about £2 per square metre. PE has a flammable polyethylene plastic core, and is considered unsuitable for buildings more than a couple of storeys tall in several countries (e.g. Germany and the USA - but not the UK). FR has a miscellaneous fire-retardant core (I've seen different fillings on different sections of the Arconic website). All versions of Reynobond are an aluminium sandwich.
I don't think anyone is pointing at Aluminium as the problem - the problem is it's a composite sandwich, available in flammable and non-flammable filling variants.
If that's the case it would explain my confusion on the issue, i had been wondering how a non fire resistant material sandwiched between metal would have spread a fire with such efficacity, however if it's like you say sheets of cladding only have metal on the external facing side it would/could explain a lot.
EDIT: Having used directhex's mention of Reynobond it does seem it uses metal on both sides bonded to a core of polyethylene.
That's what confuses me, even if the core is flammable shouldn't sandwiching it between metal significantly reduce it's flammability, i know polyethylene can catch fire but if it's between metal sheets shouldn't that cut off most of the oxygen and thusly significantly reduce its flammability, or at least not result in the sort of fire we saw at Grenfell.
Last edited by Corky34; 02-07-2017 at 11:00 AM.
It's not solid PE, it's a lattice. Lots of air. More like a foam.
so the makings of a rocket stove then....
metal skin with air gap centrally.
Either way (back on subject) the loal authority would have had to read a spec sheet to make a building look new and modern and seen it passed "a test" defined as required.
Apologies for resurrecting a year old thread but i was listening to question time last night and what with it being the anniversary (is that the right word? It makes it sound like something to be celebrated when it's not), anyhow a common theme seemed to be calls to ban certain cladding and i don't understand why people are even looking to ban cladding, shouldn't we be taking a similar approach as we do with most other things? That is saying what can be used instead of what can't, basically if your names not on the list you ain't getting in.
I was told that after the great fire of London that the government said buildings could only be made of bricks and stone (excluding doors and windows) and in both food and medicine we use the precautionary principle (wiki) that basically states prove it's safe to use instead of proving it's unsafe, so why are we not doing the same for cladding and building regs?
Generally, proving something is safe requires extensive testing of each and every material in each and every shape in each and every slightly different useage scenario, with the same all over again every time there's a situation with two or more such things used together.
Proving it's unsafe merely requires basic extrapolation of previous tests on similar scenarios.
It's cheaper and quicker to prove something is unsafe.
Besides, safe until proven unsafe is what allows innovation!
Cladding may be safe to use in appropriate situations or under certain installation conditions.
Dame Judith Hackitt's report identified the fact that inappropriate cladding had been installed incorrectly - the solution is to tighten up and simplify the regime of building control, regulation and inspection, rather than to ban a building technique that can be used safely.
It would be like banning cars because they are dangerous - yes they are if driven dangerously - which is why a test is required and the roads are policed.
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So it's money before lives, that's exactly the reason we adopted the precautionary principle, because human life is meant to be more important than innovation and/or money.
Cars aren't dangerous it's how they're used that make them dangerous and if used correctly the dangers are all but non existent, if cladding may be safe to use in appropriate situations or under certain installation conditions then why are we not saying what those situations and conditions are instead of saying what they're not?
OK, you lot go live on the street for the next couple of decades while we spend stacks of money and time testing all these materials in various combinations, uses, shapes and construction methods, to prove they're safe.... before we finally get around to building anything. Meanwhile, you save up aaaaaall the money these things are eventually gonna cost - We'll call your grandkids once everything has been built and certified as safe to use, yeah?
Or we can just rule out what isn't safe and build something affordable and usable now, if you'd prefer...?
Thalidomide isn't dangerous... it can even be used off-label. But without looking it up, I can only tell you what it's NOT to be used for.
Wasn't the cladding on Grenfell Tower for decorative purposes. So really cladding isn't necessary.
It is funny(in a bad way); they have these old blocks, crumbling and rotting internally. Inappropriate safety regulations and equipment, and very overcrowded blocks not helping in event of fire. Yet every decade they tart them up in the latest fashionable way, abstract paint job or external cladding. Meanwhile they fill every available space in the city with poorly constructed houses.
Cladding was for both decoration and insulation - if it were only decoration, then they wouldn't have bothered (and paid extra) for the not-so-fireproof foam inner when plain painted aluminium would do the job
I think the 'insulation' bit was spin, both before approval and after. If you look at pictures; pre refurbishment and after, it's to make the facade look good. But as the whole point of those blocks is that fires are contained within the 'concrete cell', adding any form of cladding would compromise that.
I think if it was just insulation, that the tenants were cold suddenly, fifty years after these blocks were put up(an average), then they would have used internal insulation on the walls. It's a perfect metaphor for 'hide the housing shortage' behind a facade.
There's no need to be facetious, there wouldn't be people living on the streets because we already know what is safe to use, like i previously mentioned after the great fire of London the government said buildings should only be made of brick or stone (excluding doors and windows), the entire population of London didn't spend decades living on the streets as we already knew brick and stone is not combustible.
It's exactly the same with cladding, we already know what cladding is not combustible so why are we talking about banning an endless variation of types of cladding, installation methods, and everything that goes along with it instead of saying this is the list of cladding and associated installation methods that must be used, if it's not on the list it can't be used.
If a company wants to sell their cladding then the onus is on them to get it approved as being safe.
And just like all prescription drugs it follows prescription based safety rules, in other words rules define when it should be used and every other use case is considered dangerous (obviously unlike building regulations we can't check that every person follows those rules but that's their responsibility)
it's a case of lack of joined up thinking I'm afraid. and it goes like this:
the government failed to build the required nuclear power stations in the 1990s (Thatcher privatised the NPPC, Major failed to push through Hinklley C, Blair burried his head in the sand)
Carbon becomes the big thing, and energy use needs to be reduced
Power costs go up too, people want to spend less on heating
The government finally cotton on that privatised power industry isn't doing any forward plannning about power generation. We face brown outs based on population growth and increase in electricity demand.
North sea gas projections are also showing a tipping point
Power security begins to become a thing in Whitehall, privately if not publicly.
Several revisions of Part L later (at least 4 in this century already) of the approved documents (the Building Regulations) which deals with insulation and thermal performance and energy use in buildings and you now can't build anything without some seriously onerous requirements for insulation and low U values.
The best things to achieve this are a) synthetic, so resistant to mould, bugs, and moisture b) lightweight so they don't increase the weight onto the foundations, structure etc c)easy to fix - time is money, d) as insulating as possible for as thin as possible so your walls, floors and roofs don't get stupidly thick taking up valuable space internally, or causing breaches of planning permission externally.
Needless to say synthetic foams win for this.
And as this march for part L continues, do you know how many revisions to the parts governing fire, quality of air, structure etc have been?
Not many. A few, but the changes have been modest. Part A barely changed in the 2010 revision, and 2013 just swapped out the old British Standards for the European harmonised Eurocodes. Otherwise, business as usual. fire had one update IIRC, and so forth. It's what happens when you put politicians in charge of something hugely technical. It doesn't take a genius to know that with any complicated thing, building, car, airplane, whatever, you need to make sure it works as a whole. And tinkering with one bit of the design guidance without considering its knock on and interrelationship with other parts doesn't work very well.
Should the designers and contractors have considered the big picture? Yes absolutely - it's their legal duty. Grenfell is not the politician's fault directly. But pushing for ever increasing retrofit U-values limits on old buildings has come from the powers that be. Had we a surplus of electric power generation from a generation of nuke power stations that was meant to be but got panned, then we'd have electricity that was not CO2 producing, no one would care about trying to shrink-wrap old buildings and, we'd all just be running the electric heaters as the need came.
Exactly. And that was the thrust of Dame Judith Hackitt's report - to simplify and update the building regulations and the enforcement of them.
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