Ecoscape 40x40x3600mm aluminium joists are easy to work with and can be used to create a decking substructure using our pedestal system or as part of a decking framework. Designed for quick and easy composite decking installation, our aluminium joists are made from recycled aluminium materials (temper T6), are weather-resistant, moisture-repellent and will not rot or splinter over time, unlike timber decking substructures. Available with a 25-year warranty.