Ducts are installed inside the walls, ceilings, and basements of a home. Ideally, they will be placed in the conditioned envelope of your home. That means they can be found in the frames of the structure.
Because of their placement, it is very time-consuming and expensive to retrofit a home with ductwork. New ductwork installation can also be expensive. Walls, floors, and ceilings will need to be opened up to place the new ducts correctly. This is why it is so important to fix any duct problems right away and not wait until your need the entire ductwork to be reinstalled.