Metal Roofing & Wall Cladding Panels — The Envelope That Faces the Weather
Roof and wall panels are the only parts of a steel building that fight rain, snow, wind and UV every day for decades — and a leaking envelope makes every other engineering decision in the building moot. We roll-form profiled steel and aluminum panels on continuous lines, with the profile geometry, coating system and fixing method chosen for the site's wind zone, snow load and the building's service life, not for the lowest unit price in the catalogue.
Profiled Sheet, Standing Seam or Sandwich — Matching the System to the Building
Three families of panels cover the practical range of industrial envelopes; the choice is governed by span, thermal requirement, fire rating and the roof's geometry.
The base material decides the panel's behaviour long before the profile does. Our steel panels use Q350/S350GD galvanized or galvalume substrate with a minimum yield strength of 350 MPa; our aluminum panels use 3003/3004 alloy with a minimum yield of 250 MPa. The difference is engineering, not preference: steel carries higher wind and snow loads at the same gauge, while aluminum gives a maintenance-free period in coastal and industrial atmospheres where steel — even galvanized — eventually asks for attention. Both are roll-formed to the profile geometry that the structure's purlin and girt spacing demands, verified to GB/T 12755 (profiled steel sheets for building) and EN 508 (self-supporting metal sheets for roofing and cladding).
Three fixing philosophies divide the product range. Through-fastened corrugated sheet — screws through the crest into the purlin — is the fastest and cheapest envelope for slopes above 5°, and with a good seal washer it is genuinely weather-tight, not just 'roofing grade'. Standing seam clips the panel to hidden brackets and seamed the joints together on the roof, so there are no fasteners in the weather zone at all — the right answer for low slopes (2–3°), long panels and high wind zones. Insulated sandwich panels combine both skins and a rigid core in one factory-made element, giving the envelope its thermal and vapor-control layers in a single fixing operation.
Whatever the system, the details decide the roof's life: side laps lapped to the weather, eave and ridge flashings with the correct upstands, seals at every penetration, and a fixing pattern verified against the project's wind uplift calculation rather than the sheeting contractor's habit. Our envelope team supplies the panels and the flashing schedules together, so the weather-tightness is designed once, in the shop, instead of improvised on the ridge.
Profiles We Roll and the Geometry Behind Them
Effective width, rib height and seam type are what the cladding's span table hangs on — get these right and the purlin schedule follows naturally.
Through-Fastened Profiles
Rigid trapezoidal and corrugated profiles fixed through the crest, for roofs and walls with slopes of 5° and above. Rib height governs spanning capacity: the deeper the rib, the stiffer the sheet in its rolling direction.
- YX15-225-900 — 15 mm rib, 900 mm cover, walls and low-load roofs
- YX25-210-840 — 25 mm rib, 840 mm cover, standard roofs
- YX35-125-750 — 35 mm rib, 750 mm cover, heavy snow or wide purlin spacing
Clipped & Seamed Roof Panels
65 mm-high folded seams connecting panels with a continuous seaming machine; fixed to hidden clips so the weather zone contains no fasteners and the panel expands and contracts freely with temperature.
- YX65-400 / YX65-430 / YX65-500 — 65 mm seam height
- Effective cover width 400–500 mm per panel
- Low-slope roofs from 2° with the lap fully seamed
- Long runs up to 40 m without transverse joints
Sandwich Panels
Two pre-painted steel skins (0.5–0.6 mm) bonded to a rigid foam or mineral wool core on a continuous laminating line — the envelope's structure, insulation and vapor barrier in one factory-controlled element.
- Core: EPS, polyurethane (PU/PIR) or rock wool
- Thickness: 50–150 mm (roof), 50–100 mm (wall)
- Skin: 0.5–0.6 mm pre-painted steel, PE or PVDF
- Roof and wall panels with factory-profiled laps and seals
Completing the Envelope
The roof's weather-tightness is decided at its edges: ridge caps, eave flashings, gable trims, valleys, gutters, pipe flashings and closure strips, all brake-pressed from the same coated stock the panels are rolled from.
- Ridge and eave detailing drawn per roof slope
- Gutters and downpipes sized from catchment area
- Closure strips at every corrugation under ridge and eave
- Neoprene washers and stainless fasteners in coastal zones
Substrate, Coating and Core — Specified, Not Implied
Every panel carries a material certificate stating substrate grade, coating type and film thickness. Here is what those lines mean.
Steel Substrate
S350GD structural grade, 0.4–1.2 mm, galvanized Z275 or galvalume AZ150; yield strength ≥350 MPa so the profile carries the span without intermediate purlins or extra gauge.
Aluminum Substrate
3003/3004 alloy, 0.6–1.0 mm, with PVDF (fluorocarbon) finish — the maintenance-free choice for coastal, chemical and food-processing atmospheres where steel coatings get tested hard.
Coating Systems
Polyester (PE) 20 μm outside / 8 μm reverse, SMP 25 μm, or PVDF fluorocarbon 25 μm outside — matched to UV exposure, chemical atmosphere and the warranty period the project needs.
Core Thermal Values
Sandwich cores specified by their thermal conductivity: EPS ≤0.035 W/m·K, polyurethane (PU) ≤0.024 W/m·K, rock wool ≤0.040 W/m·K — U-values calculated per panel thickness and verified in the envelope design.
Envelopes Across Building Types
Factory & Warehouse Envelopes
Corrugated steel roofs and sandwich walls for workshops, logistics centres and plants, with the coating system chosen for the process atmosphere — PE for dry interiors, PVDF where chemicals or coastal salt live.
Cold Stores & Freezers
Sandwich panels with 100–150 mm PU cores on both roof and walls, air-tight jointing and vapor-tight laps, delivering the U-value a −25°C room demands without condensation in the joint.
Clean Rooms & Food Plants
Hygienic wall panels with coved corners and flush joints, smooth internal faces with no exposed fixings where the panel system is specified for GMP and food-safety inspection.
Stadiums & Arenas
Long-run standing seam roofs over grid and pipe-truss structures — the profile that follows a curved roof, absorbs thermal movement over wide bays, and stands up to the wind uplift a grand-stand roof attracts.
Retail & Logistics Centres
Visually crisp trapezoidal walls and standing seam roofs for distribution hubs and retail destinations, where the envelope is the brand and panel lines must read cleanly across a 200 m facade.
Barns & Agricultural Sheds
Economical corrugated roofs over clear-span agricultural buildings, with colored PVDF sheeting where the building sits in a landscape that matters to the operation's owners.
Verified Performance, Not Marketing Claims
The four numbers that building approval and insurance both ask for, with the test or code basis stated alongside.
| Parameter | Value | Basis |
|---|---|---|
| Fire rating (rock wool core) | Class A (non-combustible) | GB 8624 |
| Watertightness | Grade 1 (no leakage in static water test) | GB/T 12755, GB/T 7106 |
| Wind uplift resistance | ≥ 4.0 kPa (standing seam test assembly) | ASTM E1592 / GB/T 50152 |
| Acoustic insulation (sandwich wall) | ≥ 25 dB sound reduction | GB/T 50121 |
The wind uplift number deserves its context: a roof's resistance to uplift is a property of the assembly — panel profile, clip, fastener, purlin spacing and seam — not of the sheet alone. We run or source the assembly test for each project's panel-and-clip combination, and we size the fixing pattern from the site's basic wind pressure (GB 50009 or the local code) with the appropriate zone factors for edges and corners, where uplift is 1.5–2 times the field value. A roof that is detailed only for the field zone fails at the perimeter; ours is never detailed that way because the flashing and fixing schedule is drawn per zone, not per roof.
For cold stores and food plants, the fire rating and the vapor control are specified together: rock wool core where the process or code demands non-combustible insulation, PU where the U-value must reach 0.024 W/m·K or better, and a vapor barrier lap detail at every joint so moisture cannot reach the core — the failure mode that quietly kills a cold-store envelope from the inside. The panel schedule we deliver lists core, thickness, coating and fixing per elevation, together with the U-value calculation and condensation check for the room conditions you specify.
Building an Envelope That Keeps the Weather Out for 30 Years?
Send your roof and wall geometry, purlin/girt spacing, wind zone and thermal or fire requirements. We recommend the profile and coating system, quote the panel lengths and flashing schedule, and ship with material certificates per lot.
Email: market@permanentsteelstructure.com | WhatsApp: +86 18621689980 | Phone: +86 516-83269982