Biogas technology provides an immense potential to generate energy from waste, the management of which has been a considerable problem both in rural and urban locations of Nepal. Many local biogas construction companies in Nepal have limited knowledge and experience in design and construction of large sized biogas plants. A wide range of large sized biogas technologies are available with enormous biogas yield potential. However, this manual focuses only on the double membrane Continuous Stirred Tank Reactor (CSTR) biogas technology. Double membrane CSTR biogas plants have higher yield, ease in operation and provides flexibility for handling different types of agro and livestock wastes. This manual has been prepared with an aim to act as a guidebook for pre-qualified biogas construction companies and covers the design, planning and construction of double membrane CSTR large sized biogas plant.