Relief Panels Are Not Flat Cladding
Standard interior cladding specifications — written for flat sheet materials like plasterboard, HPL, or stone veneer — don't translate directly to three-dimensional relief panels. Relief panels have variable thickness profiles, undercut geometries, and weight distributions that change across the panel face. A specification that doesn't account for this will create problems at installation that are expensive to resolve on site.
The good news: relief panel specification follows the same logic as any material specification. It just requires attention to a few additional parameters that flat cladding doesn't have.
The Specification Checklist
A complete relief panel specification should address the following parameters. Missing any of these creates ambiguity that the contractor will either price conservatively or resolve incorrectly.
- Material and fire classification. State the material family (e.g. polymer modified alpha gypsum) and the required EN 13501-1 fire class. Don't assume — write it explicitly.
- Panel dimensions and tolerances. Specify maximum panel size, nominal thickness, and the allowable dimensional tolerance. For relief panels, tolerance should be stated at both the thinnest and thickest points of the relief profile.
- Relief depth and geometry. Define the maximum relief depth (distance from the back plane to the highest point) and whether the geometry is from a supplied 3D file or from the manufacturer's catalogue. If from a 3D file, state the file format (STEP, OBJ, STL) and the minimum feature radius.
- Surface finish. Specify the coating system (e.g. 2K polyurethane), the colour reference (RAL, NCS, or custom match), the gloss level, and whether metallic or textured finishes are required.
- Fixing method and substrate. State the substrate type (metal stud + plasterboard, masonry, concrete) and the required fixing method. Include maximum allowable deflection of the substrate under panel load.
- Joint treatment. Define the joint width between panels, whether joints are expressed (shadow gap) or filled (seamless), and the acceptable joint tolerance.
- Pattern continuity. For designs that tile across multiple panels, state whether pattern registration is required and the allowable pattern offset at joints.
- Documentation deliverables. List what the manufacturer must provide: fire test certificates, DoP, structural fixing calculations, installation drawings, and maintenance guidance.
Fixing Methods
How a relief panel attaches to the wall is determined by three factors: panel weight, substrate type, and whether the installation is permanent or designed for future removal (common in hospitality where brands rotate interior schemes on a 7–10 year cycle).
| Method | Best For | Panel Weight Limit | Removable? |
|---|---|---|---|
| Adhesive bond (construction adhesive + mechanical backup) | Flat or low-relief panels on rigid substrates (concrete, masonry) | Up to ~30 kg/m² | No — destructive removal |
| Concealed Z-clip (interlocking metal clips on panel back + wall) | Medium-weight panels, especially where future access or removal is needed | Up to ~45 kg/m² | Yes — non-destructive |
| Threaded insert + rail (embedded inserts in panel, mounted to aluminium rail system) | Heavy or deep-relief panels; large-format installations over plasterboard on metal stud | Up to ~60 kg/m² | Yes — non-destructive |
| French cleat (angled timber/metal cleat on panel + wall) | Feature panels, art installations, single-panel accent pieces | Up to ~40 kg/m² | Yes — lift-off |
Hotel PIP programmes typically operate on a 7–10 year renovation cycle. If your client is a hotel operator, specify a removable fixing system — it reduces the cost and disruption of the next interior refresh. Z-clip and rail systems allow panel removal without damaging the substrate, which also protects the drywall contractor's warranty.
Substrate Considerations
The most common mistake in relief panel installation is underestimating the substrate requirements. A standard metal stud + 12.5 mm plasterboard partition is designed for loads of approximately 20–25 kg/m². A deep-relief PMAG panel at 25 mm average thickness weighs 35–40 kg/m² — which exceeds the substrate's capacity.
The solution is not to specify thicker plasterboard (a common but ineffective response), but to ensure the fixing system transfers load directly into the metal studs. Rail-based fixing systems span between studs and distribute the panel weight as point loads on the stud flanges, bypassing the plasterboard entirely. This is structurally sound and eliminates the risk of plasterboard delamination over time.
PMAG vs. PUCOMP — When to Use Which
The decision between PMAG and PUCOMP typically comes down to two factors: fire rating requirement and installation context. If the specification mandates A1 or A2 non-combustibility — which is the case for most hotel corridors, high-rise lobbies, and escape route adjacencies — PMAG is the correct material. If the installation is exterior, in a wet area, or requires a lightweight solution for a challenging substrate, PUCOMP is the better choice. Both materials accept the same surface finishing system, so the visual finish is identical.