A double-layer roll forming line packs two roof profiles into one machine frame, sharing the decoiler, drive and control cabinet. The lower set of rollers typically makes a trapezoidal roofing sheet, while the upper set forms a corrugated wall or roofing sheet. The operator switches between them by raising one station set and lowering the other.
For a small workshop the main benefit is floor space. Two single-layer machines take about twice the length and need two decoilers. A double-layer chassis uses one foundation and one operator, yet still outputs two different panel profiles in a day. Pay attention to the cut-off: one hydraulic cutter serves both profiles, so the die changes when switching, which takes around half a day.
The trade-off is load. A double-layer frame carries two roller banks, so the motor is sized for the heavier duty cycle, usually 5.5–11 kW. Sheet thickness stays in the 0.3–0.8 mm range for color-coated coil. If you mostly run one profile, a single-layer line costs less; if your orders mix roof and wall sheets, the double layer pays back within a normal season of orders. Budget for the extra foundation bolts and floor space, since the twin chassis weighs more than a single line. One inverter and one hydraulic pump serve both decks.