When to use this system
GS MW U combines two desirable design parameters that other panels typically do not offer together:
- Non-combustibility (A2-s1,d0) — required in public buildings >12 m tall, in fire separation bands, and in enclosures of evacuation routes.
- Façade aesthetics (hidden fixing) — a smooth line with no visible fastener heads. The choice for buildings of representative significance.
Typical scenarios:
- Hospital, government office, school — all external walls must be A2; at the same time, the institution’s image calls for a high-standard façade.
- Warehouse with combustible goods + office block at the front — office block in GS MW U (aesthetics + safety), warehouse in GS MW S (price, also A2).
- Evacuation routes and stairwell enclosures — EI 60–120 required; the U panel allows aesthetic walls in public spaces.
Hidden fixing mechanism
Specific to mineral wool: hidden fixing is provided by the PM1 washer (galvanised steel, 1.5 mm). The fastener is screwed in through the washer, which is then covered by the next panel slid into the joint. The fastener is invisible from the façade side.
| Parameter | GS MW U | GS MW S |
|---|---|---|
| Fastener | hidden under PM1 washer | visible |
| Price | +15–20% | base |
| Façade aesthetics | smooth, no gaps | linear with heads |
| Modular width | only 1000 mm | 1000 or 1140 mm |
Comparison with PIR (insPIRe U)
| Aspect | GS MW U (wool) | insPIRe® U (PIR) |
|---|---|---|
| Reaction to fire | A2-s1,d0 (non-combustible) | B-s1,d0 (combustible, NRO) |
| EI | EI 60 / EI 120 | EI 15–EI 30 |
| Core λ | 0.044 W/(m·K) | 0.022 W/(m·K) |
| Thickness for U ≤ 0.30 | ~150 mm | 80 mm |
| Panel weight | ~2.5× heavier | base |
| Price per m² | higher | lower |
Choice: non-combustibility at the price of a thicker and heavier wall. A standard trade-off for buildings with fire requirements.
Installation requirements
- Modular width 1000 mm — dictated by the hidden joint geometry.
- Lengths 2.0–12.0 m (max 16.5 m as a special order), typically 2 fasteners per panel.
- Supporting structure designed taking weight into account (~25 kg/m² at 120 mm, ~2.5× more than PIR).
- PM1 washer — key element of the hidden fixing system. Dimensionally matched to the U joint.
Required flashings
- OB-01 / OB-02 — external / internal corner
- OB-17 — panel joint cover
- OB-36 — panel closure
Technical documentation
GS MW Mineral Wool Panel Catalogue (Gór-Stal, 2025-04-23, pp. 41–46). Classification A2-s1,d0 per PN-EN 13501-1, EI 60 / EI 120 per PN-EN 1364-1.
Layer composition
| # | Layer | Thickness | λ | Role |
|---|---|---|---|---|
| 1 | External facing — galvanised steel sheet + 25 µm coating | 0.5–0.7 mm | — | external facing |
| 2 | Core — mineral rock wool MiWo (105 kg/m³) | 80–120 mm | 0,044 W/(m·K) | thermal insulation + non-combustible structure |
| 3 | Internal facing — steel sheet + 25 µm coating | 0.5–0.6 mm | — | internal facing |
| 4 | PM1 fixing washer (galvanised steel) | 1.5 mm | — | element concealing the fastener on the façade side |
U-value by insulation thickness
| termPIR® thickness | U [W/m²·K] | Meets WT 2021 (roof U ≤ 0.15) |
|---|---|---|
| 80 mm | 0,56 | — no |
| 100 mm | 0,44 | — no |
| 120 mm | 0,37 | — no |
Related catalogue items
Applications
Installation accessories
