Name a common method for sealing duct joints.

Mastic is a common method used for sealing duct joints because it is an effective adhesive that creates an airtight seal. Its application is designed specifically for HVAC systems, allowing it to withstand temperature fluctuations and resist the flow of air and moisture. When mastic is properly applied, it adheres well to the surfaces of the ductwork, filling in any gaps or seams and ensuring that there are no leaks in the system. This is crucial for maintaining energy efficiency and optimal performance of the HVAC system, as any air loss due to poorly sealed joints can lead to increased energy costs and reduced heating or cooling efficiency.

The other options, while they may have their specific uses in construction or repair, do not provide the same level of effectiveness for sealing duct joints. Glue, for instance, might not withstand the environmental conditions of an HVAC system and could break down over time, leading to leaks. Nails and rivets primarily serve mechanical fastening purposes and do not provide the necessary sealing properties that mastic does. This makes mastic the preferred choice for ensuring a reliable, long-lasting seal in ductwork applications.