All joints and seams in duct systems must be _____ to maintain vapor retarder continuity.

To maintain vapor retarder continuity within duct systems, joints and seams must be sealed. This sealing is crucial as it prevents the penetration of vapor and moisture into or out of the ductwork, which can lead to issues like condensation, mold growth, and reduced system efficiency. Proper sealing ensures that the duct system performs optimally by maintaining the intended temperature and humidity levels.

While insulation plays an essential role in thermal performance, it does not directly address the continuity of vapor barriers. Clamping joints may secure the ductwork but does not provide the necessary barrier against vapor transmission. Joining methods could refer to various techniques to connect duct pieces, but without sealing, these methods would not sufficiently prevent air leakage and moisture penetration.