Glass reinforced gypsum
GRG, from mould to installed interior surface.
GRG is an internal material. It gives a plaster surface with the geometry and repeatability of a moulded product, which is why it is used for domes, coffered ceilings, cornices, columns and decorative interior elements that could not be formed in situ.
We take a GRG package from the designer's geometry through mould-making, casting, finishing, delivery and installation, including the fixing design and the interfaces with the ceiling grid and services above it.
Scope
What the package covers.
Typical applications
- Domes, vaults and curved ceiling geometry
- Coffered and profiled ceilings
- Cornices, mouldings and decorative bands
- Column casings and capitals
- Wall panels and relief surfaces
- Feature reception and lobby elements
Design inputs required
- Design intent drawings, sections and any 3D geometry
- Setting-out and structural soffit information
- Finishes specification and required paint system
- Reflected ceiling plan with services, lighting and access positions
- Fire strategy for the ceiling zone
- Approved sample or benchmark standard where one exists
Interfaces we resolve
- Primary and secondary support steel
- Ceiling voids, service runs and access panel positions
- Sprinklers, detectors, diffusers and speakers
- Lighting details, coves and shadow gaps
- Junctions with plasterboard, joinery and stone
- Movement and tolerance at long runs
Sequence
How the work runs.
- 01
Survey and setting-out
Site or model survey to establish the real dimensions the geometry has to sit within.
- 02
Shop drawings and engineering
Panelisation, joint positions, fixing design and support requirements, issued for approval.
- 03
Material development
Mix, reinforcement and surface build agreed against the required finish and the specified system.
- 04
Samples and prototypes
Profile samples and, where geometry warrants, a full-size section for approval before production.
- 05
Moulds and production
Master pattern, mould manufacture, casting programme and finishing.
- 06
Factory quality control
Dimensional check, surface check and fixing check against the approved sample, recorded before packing.
- 07
Logistics
Protection, crating and delivery sequenced to the installation zones, not to the factory calendar.
- 08
Installation and handover
Setting-out, fixing, jointing, filling, inspection and record information at close-out.
Control
Where the risk actually sits.
Mould control, not piece control
The repeatability of GRG is decided at the mould. We set out how many casts a mould will carry, when it is replaced and how each cast is checked, because that is what protects consistency across a large ceiling.
One party for casting and fixing
When the same team casts and installs, the fixing detail is designed into the piece rather than improvised on an access platform.
Coordination before casting
Service penetrations, access panels and lighting positions are agreed on drawings before the first mould is made. Cutting a cast panel on site is where the finish is lost.
Before pricing
What we need to see.
Send what exists today. We will tell you what is still required rather than price around the gaps.
- Ceiling and elevation drawings, or the model
- Reflected ceiling plan showing services and access
- Finish specification and paint system
- Programme dates for approval, delivery and installation
- Whether installation is in our scope
- Any existing approved sample or benchmark
Evidence
Projects from the register.
Questions
What clients ask about this scope.
Send your specification
Send the drawings and the specification.
Send the package drawings, the specification and the programme date. We will confirm what is buildable as drawn, what needs development and what we would need to see before pricing.