PU sandwich panels pair a metal facing (typically 0.4–0.8 mm steel) with a polyurethane or PIR foam core weighing roughly 40 kg/m³, and modern continuous lines run at conveyor speeds up to 8.6 m/min across 600–1250 mm panel widths [S2][S4].
The buying decision sits across three independent axes: foam chemistry, metal facing, and the production line that bonds them — each axis carries numeric thresholds that determine whether a panel will hold up under cold-room, roof, partition, or fire-rated duty [S1][S2].
Core chemistry: PU, PIR, and mineral wool compared
PU (polyurethane) foam delivers the lowest thermal conductivity of the three common cores and is specified where heat-insulation performance is the priority, with PIR (polyisocyanurate) used where enhanced fire behavior and rigid thermal insulation are also required [S1]. A standard single-panel line description specifies a "rigid polyurethane foam core, CFC-free" weighing "approximately 40 kg/m³" with foam layer thickness of 10 mm or more bonded to the top shell [S2].
PIR panels are described as "clad with metal sheets on both sides, with the core material being PIR foam" and are used for "cold rooms, cooling rooms, walk-in cold rooms, and modular walls and roofs" plus flooring [S1]. Mineral wool enters the comparison when a continuous line offers the "option of a core structure made of polyurethane, PIR or mineral wool" on the same machinery, which lets a plant switch cores for fire-rated partitions without retooling [S2].
Where panel choice fails: do not specify PU where the project carries a published fire-rating requirement that the foam chemistry cannot meet on its own — the core must be swapped, not the facing. For cold rooms and walk-in freezers, PIR is the default; for fire-rated compartments, mineral wool is the safer call.
Continuous vs single-panel vs discontinuous lines
Three production architectures dominate the PU/PIR sandwich panel market: continuous double-belt lines for high-volume runs, single-panel presses for short bespoke batches, and discontinuous (DDP) systems for wide dimensional flexibility [S2]. A representative continuous line quotes "speed of conveyer: maximal speed 8.6 m/min (converting frequency to adjust speed), total length of the product line about 120 meters, total power about 350 kW, thickness of steel sheet 0.4–0.8 mm, width of PU sandwich panel 600–1250 mm" [S4].
Single-panel lines cite a "high efficiency profile geometry and a 10 mm or more thick polyurethane (or PIR) foam layer adhered to the top shell" yielding "extremely high stability" for photovoltaic roofs, new builds, renovation works, and agricultural or industrial buildings [S2]. DDP systems are positioned for "the discontinuous manufacture of sandwich elements" offering "a wide range of dimensions, facings and foam systems" — the right pick when panel length, facing swap, or foam system change is part of every job [S2].
Decision rule: high volume + single SKU → continuous line; mixed facing/cutting profiles at moderate volume → single panel; very wide dimensional range with frequent foam-system changes → DDP. Buyers who run mixed SKUs on a continuous line pay in changeover waste.
Facing gauge, width, and joint geometry
Metal facings run from 0.4 mm to 0.8 mm on the standard continuous process quoted in current supplier data, with a 600–1250 mm net panel width window [S4]. Roof-grade panels often use a four-wave corrugation profile ("Four Waves Roof Sandwich Panel") to add spanning capacity for low-pitch industrial roofs, while wall panels use flatter facings optimized for cladding aesthetics [S1].
The continuous line scope includes uncoil, rollforming, foaming, continuous press, cutting, cooling, stacking, packing, and a separate polyfilm-wrapping section — meaning gauge, profile, and length are all digitally settable on a single integrated line [S2]. For buyers, that translates into a spec band rather than a single number: a 50 mm PIR roof panel at 0.5 mm steel facing is a different buy than a 100 mm PU partition panel at 0.4 mm steel, even on the same line.
Compare three realistic buying options on numeric criteria:
- PU wall partition, 50 mm core, 0.4 mm steel, 1000 mm width: low cost, light weight, general interior use [S1][S4].<br>- PIR cold-room wall, 100 mm core, 0.5 mm steel, 1000 mm width: deeper insulation, CFC-free 40 kg/m³ core, cold-room rated [S1][S2].<br>- PIR roof panel, 80 mm core, 0.5–0.6 mm steel, four-wave profile, 1000 mm width: spanning capacity for low-pitch industrial roofs [S1].
Where PU/PIR sandwiches fit — and where they do not
Primary use cases documented in 2026 supplier catalogues are cold rooms, cooling rooms, walk-in cold rooms, modular walls, modular roofs, flooring, and partition walls in industrial, agricultural, and PV-supporting buildings [S1][S2]. BRDECO's PU/PIR sandwich wall and roof panel families are explicitly positioned for "the strictest heat insulation requirements" while "maintaining a good bearing capacity" — meaning the same panel carries thermal and structural duty, not one or the other [S1].
These panels are not the right pick for every enclosure. For projects where a published fire-rating drives the spec, mineral wool cores are typically required rather than PU or PIR foam. For highly corrosive or coastal environments, plain galvanized steel facings need a coating upgrade; otherwise service life drops. And for retrofit work on legacy buildings with non-standard framing, the standard 600–1250 mm modular width can force awkward field cuts.
Sourcing signals: catalogue, MOQ, and machinery pricing
Made-in-China listings on the panel side show a US$20.00 unit price band with a 500-piece MOQ and L/C, T/T, D/P payment terms for one PU sandwich panel offer, with the supplier's main lines covering cranes, overhead cranes, steel structures, sandwich panels, prefab wall panels, and sound-proofing products [S3]. On the machinery side, Wuxi Haoshuo Technology lists a PU sandwich panel production line at US$150,000 with MOQ not specified — a useful benchmark for buyers evaluating turnkey line capex [S7].
A 2026 supplier directory on tradeboss.com shows 52 matched companies offering PU sandwich panels as sellers, manufacturers, exporters, or wholesalers — the supply base is broad enough that a second-source qualification is realistic on most line architectures [S6]. For more on the structural framing that typically sits behind these panels, see this steel decking and siding spec map.
Selection shortlist logic
Match core to duty first: PIR for cold-room and walk-in freezer walls and roofs, PU for general partitions where lowest thermal conductivity matters most, and mineral wool for fire-rated compartments [S1][S2]. Then match facing to span: 0.4 mm steel for partition walls, 0.5–0.6 mm for cold-room walls, and 0.6–0.8 mm for roof panels that need to carry snow and wind loads across purlin spacings [S4].
Finally, match line architecture to volume mix: continuous double-belt (8.6 m/min, 600–1250 mm width) for steady-state runs, single-panel press for short bespoke orders, DDP for wide dimensional flexibility [S2][S4]. Buyers evaluating motors and drives for the line's rollforming and conveyor sections can cross-check IE3/IE4 premium math in the IE4 motor price 2026 TCO map. A PU sandwich panel spec'd against core + facing + line architecture in that order will land on the right product on the first RFQ.
Spec-level background on the components involved: linear guide, crossed roller guide, and alc panel.