One Piece Duct, stacked

One Piece Duct:  Either formed on a Full Wrap Duct Line or in the shop by seaming together two half sections of duct, this type of duct is formed into a complete duct section in the fab shop.  This cuts down the field labor cost significantly because the construction of the duct section is already compete when it arrives to the job site, leaving only the end to end connections and the hanging of the duct remaining.  The downside is simply that less ductwork can fit onto a truck, which might mean more deliveries vs the same amount of duct made in 2 piece duct.

Two Piece Duct—aka L Sections /  half sections /  KD (Knocked Down)

Two Piece Duct:  Two longitudinal seams in need of joining.  This is also referred to as unassembled, or knocked down (KD).  This type of ductwork is common because the contractor can nest it in stacked L sections and fit a lot more ductwork on a truck when transporting to a job site.  The downside is that the field crew will have to seam the two longitudinal stands on the job site.

Full wrap coil line running Two Piece Duct

Just because it’s a Full Wrap Coil Line doesn’t mean it only makes Full Wrap. Shops are going to want to create L shapes to nest it and take up less room on trucks. In this case L sections were created because they had to line it.

Stacked Four Piece Duct