Maximising the use of bio-based products is key to meeting current sustainability targets. Yet according to sustainability consultancy Metabolic, using bio-based products for half of new housing in Europe would require production of engineered timber to increase nearly fivefold, and roundwood by four and a half times. Given the improbability of an uplift in production on that scale, as well as the current rapid growth in global demand and the UK’s own limited timber harvest, using the country’s waste timber to make ‘cross-laminated secondary timber’ – CLST – would seem to make a great deal of sense. Rather than its current fates of combustion for energy recovery, chipping for MDF, dumping in landfill, and other low-grade, non-circular activities, incorporating this plentiful material into supply chains would benefit the construction industry, as well as the country’s economy and environment. And it would also seem to be a highly achievable ambition – so why isn’t it happening?