Tracy Fox and husband Steve want to build an "urban shed" featuring two studios, three bedrooms and a double-height space with a walkway, made out of industrial-style materials including corrugated cement fibreboard and 20ft panels of polycarbonate sheeting. Having discovered an old milk yard tucked away behind some flats and shops in south-east London, their long-held desire to build a highly unconventional family home and workspace begins. But their choice of unorthodox materials proves challenging and costly.