A careful deconstruction method was required to clear the site of the Packington Estate in London to make way for new-build flats.
The regeneration of London’s housing estates continues apace, with numerous schemes across the capital under way or in the planning stages.
One such scheme, the redevelopment of the Packington Estate in Islington, is approaching its final stages – and a careful demolition solution was required to clear the site of its existing buildings.
The estate was home to 538 affordable rented properties owned by Islington Borough Council.
The issue was that the blocks of flats were all built using the same construction method as the infamous Ronan Point, a 22-storey tower block in Newham, east London, that partly collapsed in May 1968 following a gas explosion.
There, the explosion blew out a number of load-bearing panels, and as the building had been constructed with panel atop panel with no structural frame to support it, a collapse ensued, killing four people and injuring another 17.
The buildings at Packington were constructed using the same method, albeit not to the same height. “There was no frame in there, it was all panel on panel and it relied on the junctions of those panels,” says Rydon Construction design and build manager Andy Page.
“The council looked at strengthening the flats, but that meant putting metal brackets on each wall and floor panel, on every panel in every room in every flat. There would be so many that they’d have to remove the residents to do it, and that blew the scheme out of the water – so it became a stock transfer on the proviso that it was all demolished and rebuilt.”
“There was no frame in there, it was all panel on panel and it relied on the junctions of those panels”
Andy Page, Rydon
That stock transfer was to Hyde Housing Association, which took over the flats and partnered with Rydon to carry out the project, with the contractor winning the contract to do each phase in turn.
The firm has completed four phases of the project so far, having begun work in 2007, and is on site with phases five and six now – the final two. Phase five started on site in September last year, with phase six beginning in January this year, with the final handover of flats expected in early 2019.
For subcontractor Maldon Demolition, though, the project is now almost at an end.
Stack of cards
The demolition has not been a simple task, due to the unusual method of construction. “It’s just a stack of cards, really,” Mr Page says. “Anywhere that we were close to neighbours [within 5 m], we had to deconstruct the blocks – [in] the opposite [way] of building them.
“We’d scaffold, prop all the wall and floor panels, and then get a crane in and lift the panels off one by one. We did that anywhere where if the building collapsed and fell it could go outside the hoarding. Once we’d taken the end 5 m off, say, and then left often a raked-back building, the rest could then be demolished with a long-reach excavator and a concrete muncher.”
This meant that the demolition process was quite time-consuming, requiring extensive planning and careful engineering of the props to ensure there was no unexpected premature collapse.
“We’d scaffold, prop all the wall panels and floor panels, and then get a crane in and lift the panels off one by one. We did that anywhere where, if the building collapsed and fell it could go outside the hoarding”
Andy Page, Rydon
“It’s taken five months to demolish that last building. If it all had to be taken down panel by panel, though, it would have taken even longer,” Mr Page points out.
Some blocks, too, had to be effectively cut in half due to the project’s phasing, meaning that only part of a building would be demolished in one phase. “To do that, again there was risk that if one panel went it could domino effect along the terrace – we had to cut a slot into the building by taking it down panel by panel, then taper it back before taking away the rest. We did empty one row of flats as a safety precaution,” Mr Page says.
Crushing and filling
Once the buildings are down, Maldon then uses an onsite crusher on all of the resulting concrete for re-use across the project.
A quirk of the site has meant there was a ready need for the aggregate: when the estate was built in the 1960s, a series of old Victorian houses had to be demolished to make way. But once that had been done, the builders at the time didn’t bother to refill the site back to ground level – so the estate sat 1.5 m below ground, with the first-floor flats level with the surrounding ground.
“We’ve used the crushed concrete to build the levels back up, avoiding the lorry loads away from site,” Mr Page says.
Maldon has carried out all phases of the demolition bar one, only missing out on phase two, and has worked closely with Rydon throughout. All of the estate’s original residents have been re-housed, with the phasing allowing them to be moved across the estate to new houses as the project progressed.
There are now just two weeks left for this complex and long-running demolition project, one that has kept the team on its toes and helped regenerate one of London’s post-war housing estates.
“It’s taken so long because of all the props and the panel-by-panel approach in certain areas,” Mr Page says. “If it had been an empty site, the whole thing could probably have been done in three or four years.”