Tyred of cement?
Clockwise from left to right:
The 1890s foundations of the terraces that once stood on the Walworth Garden site
Levelling the trenches with the garden services trainees
Donated tyres from local garages across Walworth and beyond
The finished foundations
Horticultural students and volunteers help compact the pea shingle
Angharad & Billy setting out the tyres
Cement is everywhere from fence post footings to the reinforced rebar under tower blocks. It is cheap and quick to use, however its production is a major contributor to greenhouse gases, it sucks moisture into our buildings and is labour-intensive to remove and rarely recycled. So we opted for an everyday, but unfamiliar alternative for our new low-impact horticultural therapy shelter.
Rammed-tyre foundations, with their roots in the earthship buildings of the 1970s, first passed building regulations in the UK in 1996. They are created by filling recycled car tyres (in good condition; free from rips or holes) with pea shingle. Both materials go unaltered in the process, so can be extracted and reused when a building is dismantled. Before we started we sought advice from Barbara Jones (StrawWorks / School for Natural Building), who has been building concrete-free foundations for over 20 years. Barbara gave a lecture to the students at Central Saint Martins (who we have been collaborating with). She also led a separate consultation session, specifically about rammed-tyre foundations, with the Walworth Garden team.
We began digging in February. Our first task was to clear the area of the old polytunnel footings and paving slabs to make way for our three 6m long foundation trenches. We then sourced 60 used tyres for the 15 columns that would sit along the edge and centre line of the structure. Once at depth the tyres were then placed one at a time on compacted material and filled with shingle. The shingle was then ‘rammed’ using a combination of hands, feet and tools (namely a lump hammer, a piece of 2x4 and a crowbar). Each tyre stacks one on top of another to form a solid column. Once at height the gaps between were backfilled with the previously excavated earth.
Along the way we encountered a hundred years of the garden’s history from the polytunnel foundations that were set in the 1990s to the wall footings of the 1890s terraces that occupied the site prior to the garden being built. After three weeks of digging, levelling and compacting, the tyre foundations reached groundlevel. We then laid a weed suppressant material, held down by a layer of pea shingle. The tyres extend 150mm above the shingle, leaving a sufficient ventilation cavity under the building.
Next, we start going up: Building with timber
The Horticultural Shelter Project is being led by architectural researcher and WG volunteer Angharad Davies with design and build duo Billy Adams and Freddie Wiltshire (projects include Grizedale Arts, Clitter House cafe, Cody Docks as well as private commissions), engineer and course leader at Central Saint Martins Cíaran Malik alongside his 2nd year architecture students with support from Tabitha Binding who leads regional engagement for the Timber Trade Federation (TTF) & university engagement for the Timber Research and Development Association (TRADA).
We would like to offer our utmost thanks to our partners at :
The London Marathon Trust for funding the project. The University Engagement Programme at TRADA (@TRADA) for essential timber knowledge. The TTF’s regional member The London & South East Timber Trade Association L&SETTA (@thettfregions) for timber sponsorship and supply, via Howarth Timber (@howarthtimber). Our fixtures and fittings from Rothoblaas. Lastly but by no means least Tabitha (Tab Binding @TRADA @thettfregions @TimberTradeFed) for making it all happen.
Without their support this project would not have been possible.
