Verify if the duct cleaner takes care to protect the duct work, including sealing and re-insulating any access holes that the service provider may have made or used so they are airtight.
Verify if the duct cleaner follows NADCA's standards for air duct cleaning and NAIMA's recommended practice for ducts containing fiberglass lining or constructed of fiberglass duct board.
Verify if the duct cleaner installs access doors in sheet metal ducts attached with more than just duct tape, e.g., screws, rivets, mastic, etc.
