This diagram provides a step-by-step visual guide for upgrading a cold roof to a warm roof. It includes removing the old roof membrane, installing a vapour control layer (VCL) to prevent moisture buildup, fitting PIR insulation for thermal efficiency, applying a waterproofing system (e.g., EPDM, liquid-applied roofing), and ensuring proper ventilation. Following these steps ensures compliance with UK roofing standards, including BS 5250 (condensation control), BS 6229 (flat roof best practices), and Part L (energy efficiency requirements).