Which joint or seam must be sealed as directed by standard duct sealing requirements?

The correct answer relates to the sealing requirements specified for different classes of traverse joints in ductwork. Traverse joints class C must be sealed according to standard duct sealing requirements because they are designed to handle higher air leakage potential due to their construction and installation methods.

Typically, class C joints are characterized by a specific configuration that makes them more susceptible to air leaks if not properly sealed. Sealing these joints helps maintain system efficiency, reduce energy loss, and ensure that the HVAC system operates effectively.

While other classes may have their own specifications and methods of sealing, the emphasis on class C joints positions them as critical points of focus for sealing standards to mitigate air leakage and improve overall system performance.