Replacing ductwork, including labor and materials, costs $35 to $55 per linear square foot, as of 2015. Replacement costs vary based on the size of the home, the amount of duct that must be replaced, the typical cost of local labor, the duct infrastructure and the number of vents.
A 1,700-square-foot home has about 90 linear feet of ductwork, and replacing all of the ductwork can cost thousands of dollars. However, most homes need only partial duct replacements, which considerably reduces final costs. Some energy companies, such as Duke, conduct tests on ductwork to determine the extent of damage for a nominal fee.