I am listening to Joe Duirwyn of Hartwyn talking about how to deal with concrete foundations when building a new house on the site of an old one. First, you need to have a structural survey of the existing foundations, to find out how thick the slab is, whether it is a continuous raft or strips of concrete, what condition it’s in. Once you know, you have three options: to rip up what’s there and cart it away; to leave it in situ and work round it; or if you’re lucky, you can build straight onto it.
It might feel simpler to remove what’s there and start with a clean slate but huge quantities of carbon have already been expended in producing and transporting the concrete. Digging it up and carrying it away to landfill will use still more fossil fuels and create the need for more to be used in creating new foundations. With the aim of minimising carbon use, the best solutions will leave the original concrete in place.
This year, the Pritzker prize for architecture was awarded to Anne Lacaton and Jean-Philippe Vassal who specialise in refurbishing social housing tower blocks. They have increased the amount of space available for living while improving insulation and ventilation, to reduce the cost of heating and cooling homes. Their motto is ‘never demolish’. Lacaton says
the pre-existing has value if you take the time and effort to look at it carefully. In fact, it’s a question of observation, of approaching a place with fresh eyes, attention and precision…to understand the values and the lacks, and to see how we can change the situation while keeping all the values of what is already there.*
There have been sustained efforts to get Southwark Council to calculate embodied carbon when looking at the cost of demolition versus refurbishment of its 1960s and 70s blocks. Alternatives to the demolition of the Aylesbury Estate were drawn up with reference to other examples in London – but were dismissed. The 2021 Southwark Climate Change Action Plan still hasn’t taken on the principle of ‘refurbish first’. It mentions the GLA’s draft ‘Whole Life-Cycle Carbon Assessment Guidance’ (2020) and merely talks of ‘exploring options’ for ‘encouraging the use of recycled materials in new development’.
Existing systems of grants for improvements to social housing favour demolition because they fail to consider the whole lifecycle of buildings. Practices of repair, refurbishment and everyday maintenance are ignored.
Many 1930s housing estates around London have ‘stretcher fences’ made of wire mesh mortuary stretchers used in the Second World War that were recycled by being mounted as fencing on the low brick walls. Some, like those facing the Peckham Road, were regularly painted but those on the East Dulwich Estate, just a mile away, were left to rust. The then leader of the council, who happened to be the local councillor, said that there was money from ‘regeneration’ for taking them down, but not for maintenance. He shrugged.
The ‘tear it down and build anew’ approach can no longer be afforded.