Glass Fibre-Reinforced Gypsum Specifications

Posted on 22nd March 2022

grg ceiling panel struture

Before deciding on material options for planned architectural projects, you may first need to familiarise or re-familiarise yourself with the specifications of individual materials. This may involve becoming more informed about glass fibre-reinforced gypsum, which may also be found written as glass-reinforced gypsum, or shortened to GFRG or GRG.

Below, we have provided more information on glass fibre-reinforced gypsum specifications, going into greater depth about physical, material, and workmanship characteristics. Read on to learn more or contact us right away if you would prefer to speak to a team member about what this material could help you to achieve with your project.


Specifications of Glass Fibre-Reinforced Gypsum

Here, we have set out a series of tables detailing glass fibre-reinforced gypsum specifications as they might typically appear when manufactured:


Physical Characteristics

Water Penetration The material shall be suitable for all internal applications, and should not absorb moisture which may be present through excessive humidity.
Fire Propagation BS476-6: 1968 as amended by AMD 549 July 1970

The material shall be designated P (i.e. to achieve Class 0) and have a final fire propagation index of 0.9, with indeterminate indices:

i 1 0.69

i 2 0.06

i 3 0.12

The material tested shall produce no smoke.

Surface spread of flame: the material shall be tested in accordance with BS476. Part 7; 1971, and shall be classified as Class 1.

Non-combustibility: the material shall be tested in accordance with BS476. Part 4; 1970, and shall be classified as NON-COMBUSTIBLE.

Chemical Resistance The material will not be required to be exposed to liquid chemicals or deliquescent crystals.
Thermal Insulation The material shall have a thermal conductivity (K) value of no greater than 0.375 W/m deg. C.
Density The material shall incorporate a surface gel-coat and have a density of 1660 kg/m³.
Expansion The material shall have a thermal coefficient of expansion not exceeding 14.94 x 10-6/ deg. C.
Structural Characteristics The material shall have an ultimate tensile strength of not less than Bending Strength.
Anti-Static The material shall hold negligible static charges in order to minimise dust attraction.
Ultraviolet The material shall not be affected by ultraviolet light.
Asbestos The material shall contain no asbestos.
Fungoid Attack The material shall not sustain fungoid growth under normal conditions.

Material Characteristics

A continuous strand mat should be laid down in multiple layers to provide thickness and strength of the laminate.

Plaster The material should use high-quality alpha hemihydrate casting plaster with a low expansion coefficient.
Glass Fibre Glass fibre specifications state that the tissue is to be used in the material as a first layer, in order to produce a smooth finish.
Polymer Patent polymers should be used to achieve improved tensile strength and to reduce the permeability of the plaster.
Water Clean water that is fit for drinking should be used in the material. This should be used in such proportion as to ensure maximum workability and maintain the optimum water/plaster ratio.
Mould Release Agents Proprietary mould release agents or waxes should be applied to the moulds between each production. These agents or waxes should not have any adverse effects upon the surface of the component.

manufacturing grg column cover

Workmanship Characteristics

Design Mix All components should be manufactured to a consistent mix. All constituent materials should be accurately gauged, batched, or weighed.
Curing All components should be cured for 12 hours in a dehumidifying oven at a constant thermostatically controlled temperature of 30°C. The moisture extraction rate should maintain a relative humidity of 30%.
Quality Control All components shall be individually inspected. Any surface blemishes shall be rectified as need be.
Painting The material can be painted.

The GRG mouldings offered by us are all created to fine detail, using the most efficient and precise computer-aided design (CAD) tools. They are then manufactured to tight tolerances, ensuring a smooth fit for all finished pieces.

What Will This Provide for Architectural Work?

The specifications of GFRG make it a very adaptable material. The lightweight nature makes pre-formed pieces easy to install, ensuring any work carried out is fast and not labour intensive. The flexibility of the material during the moulding process also means that practically any shape of design or finish can be achieved quickly and in a cost-effective way. As a result, the work is often more economical than other material installations.

While the material specifications of GRG mean the material is lightweight, it is also important to note that they also give it high strength and surface hardness. This keeps any installation durable and hard-wearing so that the designs formed and installed have the potential to last for many years to come. The density of the material may also be increased where necessary to accommodate acoustic needs.

The adaptability and changeable nature of the material provide ample opportunity for the creation of architecturally complex pieces, and the material can be dressed and decorated to match or to act as a focal point for the building’s design concept. This includes having paint applied in a range of styles and colours to replicate certain textures. GFRG is also able to accommodate speakers, sprinklers, alarms, cameras, lighting, and other features.

As a Class 0 fire rated material, it is also expected that GRG should be completely fire retardant. This means it should help to prevent the spread of fire in the event of one.



grg ceiling panels installed

For More Information on GFRG Specifications

If you have any questions related to glass fibre-reinforced gypsum, its specifications, or where it is most appropriate for use, contact Design & Visual Concepts today. As a UK-based manufacturer of bespoke GFRG mouldings and products, we are confident that we will be able to supply the answers you need.

We will also be able to assist you in placing your order for high quality, custom-made GRG products from the moment you get in touch. By working with us, you will always be guaranteed a fast service that supplies, delivers, and installs the exact products you have specified, meeting all requirements and ensuring projects can move forward without the need for overly detailed paperwork.

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