Professional air duct sealing costs between $500 and $4,000 per square foot, with typical totals ranging from $375 to $6,000 for your home. These ducts are responsible for distributing heated or cooled air throughout your home, and any imperfections can lead to significant energy loss. Get free. Homeowners commonly pay to seal ducts to reduce air leaks, improve efficiency, and cut utility bills. The price and budget vary with project scope, labor time, and whether indicator tests or warranties are included. This means your HVAC system has to work harder to maintain comfortable temperatures, leading.