So after finishing up talking about the late 70s, let’s rewind to the 60s to look at why LPS fell from grace, because the story of Ronan Point is really the story of all LPS, and frankly it was a matter of when, not if, something like this happened.
So as I say, on 16th of May 1968, Ivy Hodge woke up early and popped the kettle on to make a cup of tea. Unfortunately her somewhat ancient gas cooker - which had come with her from her old flat in West Ham when she moved into the new block a few weeks previously - was acting up (some blame the fact that Canning Town was still on Town Gas from Beckton, which was notoriously inconsistent towards the end of its life) and...
At first glance you might think the collapse of Ronan Point was caused by some gigantic explosion near the bottom of the building. In fact, Ivy’s flat was on the 18th floor (of 22), and the explosion - while it blew poor Ivy clear out of her kitchen - left her unharmed apart from some lightly-singed fingers, ringing ears and a bruised bum.
The pressure was sufficient to blow the entire structural outer wall panel off of its joints. The floors above, now unsupported, promptly fell into the gap, destroying the walls below - you can see that the floors below absorbed progressively more and more of the collapse. 4 people died and 17 were injured. a blessedly small number considering the destruction, because the block had only just opened and many flats were empty, and the early hour meant most people were in their bedrooms, safely away from the damage to kitchens and living rooms.
The architects of the building said that such a collapse should have been impossible. Removing one panel (or indeed all of the exterior panels in one flat) should not have caused the panels above to fall into the void - they should have been supported by the adjoining panels. Also even a much larger outward pressure should not have torn the panel from it’s joints like that - the system they used didn’t rely entirely on the joints as some did but actually interlocked the panels with a tongue-and-groove system designed to speed construction (older systems required a crane or external jigs to hold the panels together while the joints were installed - this way allowed the panel to be dropped in and left in place to be installed while the crane went back for the next panel).
The pressure wave from the explosion, by the time it reached the exterior wall of the kitchen, was estimated to be only about 2 psi. Now when you multiply that by the size of the wall it’s a pretty big load - but it’s only equivalent to a wind gust of about 70mph, something that happens an awful lot in this country. While some argued that it was in a direction opposite that wind would normally come from, that kind of pressure could easily be caused by the large living room windows breaking in high winds striking the building at the right angle - a failure mode that light wood-framed construction frequently exhibits.
Unfortunately the reason for the spectacular failure was found even as the rubble was being cleared away, and the big clue was what was in - or rather what *wasn’t* in - that rubble.
I mentioned it in the last posts but the original system homes had used plates and brackets to hold the panels together - the panels were drilled or carved on-site because the panels were more-or-less universal, so you needed to install different hardware depending on whether or not you were putting the panel in the corner or middle of a wall, or if it was to be used as a floor. These plates and brackets were parallel to the surface of the slab, meaning they effectively disappeared once the panel was in place - this is part of why they’re so hard to maintain.
LPS cast holes into the edges of the panels at the factory, which you lined up with the equivalent holes in the adjoining panels and then stuck a bolt through. For floors you then attached a steel strap to the bolts at the top, which went through holes in the floor panel and were tightened up (allowing the building to settle and move with expansion and contraction without putting stress on the panels). The fixings were then hidden behind concrete poured into a mould around them, protecting them from the elements and also completing the insulation and fire compartmentalisation.
Except - as anyone who’s ever assembled cheap flat-pack furniture can tell you - the holes almost never lined up. Mass-production is never perfect and for something on this scale some problems were inevitable - cheap moulds started to go out-of-true as they were used, the reinforcing steel was frequently out of position meaning the concrete didn’t quite contract right as it cured, and often the plugs that marked out the holes were dented or otherwise damaged. The relentless pressure to get the panels out of the factory to the sites meant that even when these problems were known, they were almost never fixed.
Once on-site there was very little chance to fix these problems. In theory mostly all that was needed was a quick re-drill of the holes but the workers putting the buildings up weren’t trained to do this (after all the whole point of LPS was to minimise the amount of skilled labour required) and even if they were they lacked the equipment to do so, and were under intense pressure to keep to extremely ambitious timetables. Of course even if this weren’t the case, they were being paid piecework so slowing down to fix the problems came out of their own pockets. Workers on the sites developed a slew of workarounds - smaller bolts were used, or bolts were omitted altogether.
An extremely negligent inspection regime (after all, these were mass-produced buildings so if the first one went up fine the next hundred should too!) and the fact that by the end of the day these joins would be covered in concrete meant that these flaws were completely hidden from view until they suddenly and spectacularly were not.
There had been rumblings of problems before Ronan Point. A block in Hammersmith had an entire floor slab collapse (thankfully before the building was occupied) because it was not actually attached to anything, instead just balancing on an internal wall. In Hackney a 16’ by 16’ panel fell from the outside of a building - on inspection it had been held in place only by the sealing mastic, without a single bolt. These were dismissed as simple one-offs, but Ronan Point made it impossible to ignore.
An urgent programme of inspections was undertaken, and the results were extremely grim. One of Ronan Point’s sister buildings on the same estate was found to have a two-inch gap between the wall and the floor slab, stuffed with newspaper and covered with a skirting board. Puts load-bearing drywall to shame, really.
Surprisingly there seemed to be no rhyme or reason as to which blocks had been badly put together. Blocks on the same estate were found to run the gamut from near-perfect (none were perfect) to terrifyingly sub-standard. Some floors were fine, others completely missing joins. One theory put forward was that the variations reflected the weather at the time - in cold, wet weather the workers were even less inclined to spend the time on getting things right. Stacked against that though was that far fewer problems were found with the early LPS buildings, put up during the punishingly cold winter of 1963/64, than with later models - including Ronan Point - built in the warm and dry summer of 1967. The trend was definitely downward over the life of LPS though, perhaps reflecting the fact that the LCC (and from 1965 GLC) employed no extra surveyors to deal with the explosion in house building, replying on the builders themselves to inspect the majority of works. These builders were of course disinclined to fix the systemic issues because they were - just like the low-level assemblers - effectively on piecework, and got paid based only on whether or not they met their targets, not on the actual quality of what they did.
Worst of all, it was discovered that Ronan Point wasn’t the worst - in fact was probably about average. Dozens of buildings were condemned and demolished through the early seventies. Ronan Point was rebuilt (with the builders rather bravely claiming that the great thing about LPS was that this was a simple thing to do) and it’s defects rectified, although unsurprisingly only one household of the 88 in the block chose to return. Others were patched up, and many were left, flaws and all, for some poor buggers in the future to fix.
Gas cookers and heaters were also banned from new construction and removed from existing ones as a result. This is a much bigger thing than it might sound to modern ears. Cookers weren’t included with your flat, and were often the most expensive purchase many households made. Poor Ivy had to take her stove with her when she was moved into a new (ground floor) flat because she couldn’t afford to replace it. Also most of these blocks hadn’t been built with electrical wiring capable of powering an electric cooker even for those who could afford it (after all, everyone had gas stoves! Why waste money on all that copper?), so that had to be retrofitted at great expense.
The fact that moving to a tower block now meant you had to abandon your faithful old Belling and use an expensive and vastly inferior electric hob was therefore just another nail in the coffin of the grand high-rise vision.
The Big C
While the post-Ronan Point scramble to fix the LPS stock was underway, the opportunity was taken to fix another major problem with many of them. Many early LPS blocks were single-skinned - the exterior panels were also the interior walls with a cosmetic facade. This wasn’t quite as bad for thermal insulation as you might think - concrete is a terrible conductor of heat - but the outer walls were still slightly cooler than the rest of the house. This caused condensation and mould, which were notorious problems with these blocks - and by attracting moisture to the walls (and being open to wind and rain on the outside) any flaws in the concrete could allow water in to corrode the rebar or joints. Well, as they were having to put scaffolding up to fix the joints, might as well slap something on the outside to protect the concrete, too. These problems had been noticed very early in the LPS era and from 1964 onwards various outer skins were applied to them, offering insulation, weatherproofing, and at least some visual variation for the mass-produced blocks. Mostly they just used - unsurprisingly - large concrete panels, but multiple materials were tried, from fibreglass to mosaic bricks. A new word entered the vocabulary of high-rise builders - “cladding”.
At the same time, a new problem arose. They needed to use something to maintain the distance between the inner and outer panels, and also to give something for the outer panels to attach to. This is an extremely old and well-known problem, and the solution - battens - are almost as old as building itself. So the builders used battens, made out of the material that had been used for battens pretty much all that time - wood. The problem came to light when they went to attach a new cladding to the outside of a block in Farringdon, and fell foul of possibly the oldest still-extant building regulation in the world. No building within the City of London had been built with timber as a structural element since 1666, when the Great Fire had presented London with an exciting development opportunity.
While some scoffed at 300-year-old building regulations being enforced in The Jet Age, more boring heads patiently pointed out that the entire fireproofing scheme of these blocks was compartmentalisation - the idea that fire could not spread from one dwelling to another. LPS is supremely good at this - concrete is, as I’ve said, an incredibly effective insulator and a full blaze in the flat next door would take an hour or more to heat the adjoining wall to the point that paper on the other side would ignite. Running wood up the side of the buildings completely defeated this - and in fact it was demonstrated in laboratory tests that flammable materials between the wall panels would burn spectacularly well, the void between the walls acting as a chimney, blasting fresh air at the fire. As the windows and balconies projected through the cladding, any fire in the void would be able to spread very quickly into other flats. This was demonstrated in 1973, by the way.
Wooden battens were replaced with steel, and the problem of fire spreading along the outside of buildings was fixed forever and definitely wouldn’t ever come back again.
I was going to write a lot more about Grenfell here but to be honest it’s just too depressing. The one observation I will make is that Grenfell, as a very late high-rise, is a sort of interesting hybrid of LPS and cast-in-place and of sufficient quality that it didn’t really need the extensive work that most LPS blocks underwent in the 90s and 00s. The reason it didn’t get big repairs until after the building regs had been changed is because it was probably one of the best-built blocks of the era. Just like Robin Hood Gardens, it was doomed by not being as shit as the others.
Rebirth and end-of-life.
LPS was only ever intended to be a stopgap - the idea was supposed to be that these buildings, like the prefabs and systems they replaced, would in turn be replaced by better ways of building as they came along. At the end of the last post I mentioned some of these systems used by the GLC before the Tories came along and fucked everything up. Through the 80s and 90s a lot of LPS buildings in the “Not bad enough to be fixed after Ronan Point, not good enough to be saved” camp were demolished, and replaced with various combinations of low- and mid-rise blocks. Let’s take a really quick Google-assisted tour of some of these.
Goldwing Court, on the site of Ronan Point. Half of the estate was sold to Barratt Homes, who put up these 80s-tastic “executive homes”. The rest of the estate was replaced with cottage flats like these:
Interestingly the cottage flats actually have a bit more space, and benefit from district heating, so now actually go for more than the privately-built ones.
A few miles north, the Trowbridge Estate in Hackney demonstrated (to the annoyance of the contractors) just how solid even flawed LPS buildings could be:
https://www.youtube.com/watch?v=6BZTfBgf-0U
Bear in mind these blocks were said to be in imminient danger of collapse… In the defence of the demolition company though it was a hell of a dodgy location to be blowing up a building, wedged as it is between the Blackwall Tunnel approach and the East Anglian main line on one side and the Northern Outfall Sewer - carrying the sewage of four million people - on the other.
On the site now the inevitable yellow-brick low-rises that are the signature of the late 90s/early-00s Housing Associations.
Finally the Lefevre Walk Estate, one I’ve mentioned a couple of times as probably the worst estate in east London. Bizarrely I can’t find any decent pictures of it without watermarks, so instead have the video to Animal Nitrate by Suede, which was filmed around there:
https://www.youtube.com/watch?v=i7mEB2wnDLQ
Yet more yellow-brick low-rises, which are already falling apart apparently.
And what of the survivors? Almost all now have been clad in something or another (thankfully, as mentioned, a lot of the London social housing stock was so shit that it was re-clad in the 80s and 90s when regulations were still fairly good).
Bowsprit and Midship Points, the blocks I used to demonstrate early LPS, also make a good demonstration of the better end of the 90s refits:
The brick-faced concrete original cladding was plastered over to prevent water ingress (these blocks had their floor panels projecting through the outer walls), and the big structure on the roof was to provide a much larger water cistern to fix problems with water pressure in the flats. That white stripe down the side, by the way, is covering the gas pipes that were put back in after being removed following Ronan Point - that’s a really good indicator of a 90s refit, if you’re playing along at home.
The big problem though is that many of these blocks are now past their design life, particularly the projected life of the joints. Replacing them is a massive task, and not one that can really be done while the buildings are still occupied. Maybe 200,000 people are living in blocks in this situation and it’s not like London is overflowing with places to put them. The thing is though that - in most cases - replacing them is still quicker and less disruptive than demolishing and replacing. A lot of HAs are making noise about demolition though, because ultimately - just like Poplar HARCA, which kicked off all these words - they have no way of getting the money for repairs, but with replacement they have the chance to wack the density knob right up and sell flats privately, something that then gets the developers and banks willing to loan them money.
If - when - Labour get in and new housing starts to be built at scale with central Government funding, these old LPS blocks will almost certainly be part of the London skyline for years to come. It just turns out the gap they’re filling is half a century longer than those starry-eyed optimists thought...
No comments:
Post a Comment