Abstract: A storage system comprising a portable building having a climate-controlled interior space and a plurality of hazardous materials storage cabinets disposed in the interior space. The portable building contains no water sprinklers and no smoke detectors and has a floor that is sealed to prevent leakage of liquid. Each cabinet comprises metal double walls separated by an air space and a liquid-tight containment sump. Each cabinet is configured so that fire cannot spread from a space above a shelf to a space below the shelf. The storage system further comprises an electrical power connection and an HVAC unit mounted to an exterior of the portable building.