Ductwork is the network of ducts in an HVAC system that distributes heated or cooled air throughout a building.

Ductwork refers to the system of enclosed passages used to deliver and return air as part of a heating, ventilation, and air conditioning (HVAC) system. It distributes conditioned air from equipment such as furnaces or air handlers to occupied spaces and carries return air back for reconditioning.

In construction, ductwork is typically fabricated from materials such as galvanized steel, aluminum, flexible duct, or duct board. The layout and sizing of ductwork are carefully designed to ensure proper airflow, pressure balance, and energy efficiency. Ducts may be installed above ceilings, within walls, under floors, or exposed in certain architectural designs.

Properly designed and installed ductwork is essential for indoor comfort, system efficiency, and air quality. Poor sealing, undersized ducts, or improper routing can lead to air leakage, noise, uneven temperatures, and increased energy costs. Building codes and mechanical standards govern duct materials, insulation, fire resistance, and installation practices to ensure safe and effective performance.

Leaky ductwork can account for up to 20–30% of energy loss in some HVAC systems, making proper sealing a major efficiency upgrade.