GRG internal wall panels are the usual answer when an interior wall needs a sculpted relief, a curved feature wall or a column cover that plasterboard cannot form cleanly. The questions that decide whether the wall works are practical ones. How heavy is the panel, how thick is it, what does it fix to, and how do the joints and openings line up?
What a GRG internal wall panel is
Glass reinforced gypsum (GRG, also written GFRG) is a gypsum plaster matrix with glass fibre reinforcement, sprayed or laid up in a mould and compacted to remove air. The fibres carry the tension, which is why the panel can be thin and still span between fixings. Our GRG and GFRG explained article covers the material family and the terminology; this one is about sizing and fixing it to walls.
ShapeShell™-RG is ShapeShift Technologies’ reinforced gypsum. Its data sheet lists 4 to 5% glass fibre content, polymers in the mix for impact resistance, and moulding to ASTM C1381 for shapes including column covers, vaults, domes and light covers. Panels cure in a humid environment for 1 to 3 days before demoulding, trimming and finishing. The face comes out of the mould ready for primer and paint.
Two features matter for walls. First, the mould face is the finished face, so a CNC-machined mould reproduces the same relief on every cast, and a pattern can run across many panels. Second, fixing lugs, threaded inserts and steel frames can be cast into the back of the panel where the geometry needs them, as our GFRG knowledge entry notes. That is what lets a deeply profiled panel fix to a flat stud wall.
Weight and thickness of GRG wall panels
Weight drives the frame, the fixing centres and the handling plan, so start here. The table sets the ShapeShell™-RG figures against ShapeShell™-RC (GRC), the usual alternative when an internal wall is wet, heavily trafficked or continues outside.
| Property | ShapeShell™-RG (GRG) |
|---|---|
| Thickness | 12 mm |
| Weight | 23 kg/m² |
| Flexural strength (MOR) | 24 MPa (ASTM C947) |
| Compressive strength | 49 MPa |
| Water absorption, 24 hours | Less than 1% |
| Use | Interior only |
The data sheet also describes ShapeShell™-RG as 30% lighter than GFRC. For a quick check of your own panel sizes, the panel weight calculator takes a weight per square metre and panel dimensions.
Weights are for the panel. Add the cast-in steel and any acoustic backing, and check what the stud wall and its head and base tracks can carry. As a worked example, a feature wall 3 m high and 8 m long is 24 m², or about 550 kg of GRG at 23 kg/m². A single 1.2 m by 3 m panel is about 83 kg, which is a two-person lift or a panel lifter.
Thickness is not fixed by the material. Our GFRG knowledge entry gives typical GRG shells across the industry as 3 to 6 mm and 10 to 25 kg/m², while the ShapeShell™-RG data sheet publishes 12 mm and 23 kg/m². Deep relief adds local thickness and weight, so use the data sheet figures as the base and confirm the section for each panel with the engineer.
Fixing GRG wall panels to the structure
The ShapeShell™-RG data sheet says panels can be installed with the same standard components and techniques used to build a secondary frame for drylining, then mechanically fastened with standard drywall fixings. On a wall that means three parts: a stud frame or battens standing off the base wall, set to the panel line, and fixings from the frame into the panel or its cast-in lugs.
Alt text: Plan section through a GRG wall lining. A stud frame stands off the base wall; cast-in lugs of different depths connect the studs to a 12 mm GRG panel with a sculpted face, with a set joint between panels and an outlet opening cast into the panel.
The data sheet publishes fastener test values that help the engineer choose fixing centres:
| Test | Result | Method |
|---|---|---|
| Nail pull-out | 2,618 N | ASTM C473 |
| Fastener pull-out, metal stud | 98 kg | Data sheet, no method stated |
| Fastener pull-out, timber stud | 2,040 N | Data sheet, no method stated |
| Fastener push-through | 159 kg | Data sheet, no method stated |
| Humidified deflection | 3 mm | ASTM C473 |
These are test results, not design capacities. The engineer applies the appropriate factors and checks studs, tracks, brackets and anchors as one system. Stud size, spacing and fixing centres are set in that design, for gypsum wall linings usually with reference to AS/NZS 2589 [verify].
For relief panels, the frame rarely follows the profile. A flat stud or batten line with cast-in lugs or short brackets to each panel is simpler to set out and plumb. ShapeShift Technologies’ design team uses the same 3D model that drives the moulds to place lugs, so the brackets land on the studs.
[Photo placeholder: back of a GRG wall panel in the factory showing cast-in fixing lugs and ribs, even workshop light, 4:3]
Suggested caption: Cast-in lugs on the back of a GRG panel let a sculpted face fix to a flat stud wall. Alt text: Rear face of a glass reinforced gypsum wall panel with fixing lugs and stiffening ribs cast into the shell.
GRG feature walls, column covers and joints
A feature wall is rarely one piece. Panel size is set by three limits: what the engineer can support from the frame, what the mould and factory can cast, and what fits through the delivery route on site. That last limit is the one most often missed: lift car dimensions, corridor turns and door openings set the largest panel that can reach the room, and on walls the panel height usually hits the lift first.
Split lines should follow the pattern. On a relief wall, place vertical joints where the pattern repeats, so one mould casts every panel. On a round column, two half-shells meeting on vertical lines clamp around the column and come from the same mould. Repetition is where the tooling cost is recovered; our internal solutions page gives lift lobbies repeated over forty levels as an example of this at scale.
Joints between castings can be taped, jointed and sanded with standard drylining techniques for an invisible finish, according to the data sheet. Where a crisp line is wanted, an expressed shadow joint can be designed into the mould edge instead. Detail the base with a skirting or shadow line rather than butting the relief to the floor.
Plan openings before the panel is cast. Power outlets, switches, signage fixings and recessed lighting all need openings, and a hole cut on site through a relief face rarely sits right. Cast openings, set-downs and backing for fixtures into the mould, positioned from the same model as the services layout.
[Photo placeholder: GRG sculpted feature wall in a hotel lobby or lift lobby, straight-on view with even interior light, 3:2]
Suggested caption: Repeated panels from one mould make up a GRG relief wall. Alt text: A white glass reinforced gypsum feature wall with a repeating sculpted relief across identical panels.
Impact, fire, moisture and movement
Walls take knocks that ceilings never see. The data sheet lists polymers in the mix for impact resistance but publishes no impact test value. In corridors, lift lobbies and back-of-house routes, ask the team for impact data, or consider ShapeShell™-RC for the lower part of the wall.
Fire performance should be stated from the product’s own test report, not from the material family. Our GFRG knowledge entry makes this point and recommends describing GRG as gypsum based and fire resistant by nature, rather than calling it non-combustible.
For ShapeShell™-RG, the data sheet reports:
- flame spread index 0 and smoke developed index 0 to ASTM E84
- 19% mass loss at 750 °C to ASTM E136
- gross heat of combustion of 0.7 MJ/kg to ISO 1716
- Class 1 surface spread of flame to BS 476 Part 7
Under the National Construction Code, Australian wall and ceiling linings are classified by group number tested to AS 5637.1, so ask for that report for the specific product and finish [verify]. Our article on fire rating methods across global standards explains how these tests differ.
Moisture is the main limit on GRG. ShapeShell™-RG is an interior material, and the material page points to ShapeShell™-RC for exterior work. Keep it out of wet areas such as showers, pool halls and commercial kitchens unless the team confirms the treatment suits the conditions.
For movement, the data sheet gives a thermal expansion coefficient of 9.7 µm/m·K and says drywall criteria for movement control and building expansion joints can also be applied. Carry building expansion joints through the wall rather than bridging them with a cast panel. Where a wall runs to the slab above, the head detail should let the slab deflect without loading the panels.
Specification checklist for GRG internal wall panels
Work through these before tender so the wall is priced on the design that will be built:
- State the material, the published thickness and weight, and require the supplier’s data sheet with the submission.
- Define the relief with a 3D model, not only elevations, and mark which faces are visible.
- Set the largest panel by the delivery route as well as the structure.
- Show split lines on the pattern repeat, and the joint type: set and sanded, or expressed.
- Locate every outlet, switch, signage fixing and light before moulds are cut.
- Require cast-in lugs or inserts at fixing points, positioned from the shared model.
- Have the engineer design studs, tracks and fixing centres for the full panel weight.
- Mark impact zones and the material or protection used in them.
- Ask for the fire test report for the specific product and finish.
- Confirm the paint system, level of finish and base detail, and carry building expansion joints through the wall.
Alt text: Flow diagram. Three limits (structure and frame, mould and factory, delivery route) feed one box: the largest panel is the smallest of the three. That leads to setting split lines on the pattern repeat, placing cast-in lugs from the 3D model, and locating outlets and openings before moulds are cut.
For a wider material choice, see choosing the right fibre reinforced material. For the external equivalent of this checklist, see GFRC panels: sizes, thickness, fixing and cost.
Common mistakes
Sizing the frame for the panel alone. The 23 kg/m² figure is the GRG. Cast-in steel, deep relief and backing all add load to the studs and tracks.
Choosing panel size in the factory, not on site. A panel too tall for the lift has to be split late, which means a new mould edge through the pattern.
Cutting openings on site. An outlet or sign fixing cut through a relief face is visible and weakens the panel edge.
Calling GRG non-combustible in the specification. State the tested result for the product, as above.
Using GRG where it gets wet or knocked. Use ShapeShell™-RC or ShapeShell™-RT for wet areas, and plan impact zones in busy corridors.
Next step
If you are detailing a feature wall, column covers or a sculpted lining, send your drawings for a panel and fixing review. The ShapeShift Technologies team will propose split lines, panel weights and fixing points from your model. You can also see our internal bespoke solutions for the full range of interior components.
