You seem to want to purge or perform what amounts to a high pressure wash on a power room’s reinforced concrete (RC) roof. Steps for High-Pressure Washing an RC Roof Safety Preparations: Electrical Safety: Since this is power room one must ensure all electrical power is switched off otherwise make sure the electrical facilities are well protected by waterproofing. Personal Protective Equipment (PPE): Able-bodied employees should be permitted to work untied and are encouraged to wear