Heating, Ventilation, and Air Conditioning (HVAC), plumbing, and electrical materials including PVC, galvanized metal, insulated and non-insulated electrical wire, PVC cement, drywall joint compound and other necessary solvents and chemicals. (The phrases “occasionally,” “regularly,” and “frequently” correspond to the following definitions: “occasionally” means up to one-third of working time, “regularly” means between one-third and two-thirds of working time, and “frequently” means two-thirds and more of working time.).