Symposium Siop: an Exploration of Sustainable Building Materials

Centre for Alternative Technology; MArch Students, Machynlleth, 2021


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Symposium Siop repurposes the existing siop (Welsh for shop) at the Centre for Alternative Technology, Wales (CAT) into an ever-changing exhibition and gallery.

The intervention is a celebration of sustainable materials, with the new furniture and interior layout facilitating the cross-fertilisation of ideas and knowledge of sustainable building materials between CAT students and the wider public in a playful and reflective way. The project was designed by CAT sustainable architecture master’s student Freya Bruce and realised within the space of one week, aided by her fellow students, tutors and local carpenter Jenny Hall.

The three table plinths feature the use of hemp-lime, rammed earth (sourced locally) and a mix of hemp-lime and dark grey slate dust in a monumental celebration of low-impact natural materials. The seating elements are constructed from birch plywood, softwood battens and hundreds of precisely tapered timber chocks, which combine to create the unique, curved benches and the feature arch.

The design aims to minimise waste by using standard batten dimensions and maximising the timber used from the plywood sheets by using both the positive shapes and the offcuts. The small number of unused timbers left over from the construction were then repurposed into exhibition frames to again minimise waste.

The paint colours were inspired by the natural palette that can be seen across the wildlife-abundant former slate mine of the CAT site. This is highlighted by the natural light within the space, forming striking shadows through the furniture battens at certain times of the day.

The modular elements can be adapted to reconfigure the space for changing exhibitions and events. The heavy table plinths are carefully designed to be safely moved around with a pallet truck to ensure continued flexibility of use.

Annual CO2 data was not provided


  • Begun: Jul 2021
  • Completed: Jul 2021
  • Floor area: 137m2
  • Sector: Retail
  • Total cost: £2,060
  • Funding: Private donations and CAT teaching budget
  • Tender date: Jun 2021
  • Address: Centre for Alternative Technology, Llwyngwern Quarry, Pantperthog, Machynlleth, SY20 9AZ, United Kingdom


Hemp, Slate