Fibre Reinforced Facade Encyclopedia: Materials
Fibre cement is a sheet material made from Portland cement, finely ground silica, cellulose fibre and water, formed in thin layers on a rotating cylinder, pressed and then autoclaved under steam pressure. It is produced as flat sheets, planks, boards and profiled panels, and is one of the most widely used external cladding materials in Australia because it is dimensionally stable, generally tested as non-combustible, and inexpensive per square metre.
A 9 mm fibre cement cladding sheet weighs about 13 kilograms per square metre. A 15 mm compressed fibre cement sheet, used for flooring and heavy duty cladding, weighs about 27 kilograms per square metre.
At a glance
| Property | Typical value | Note |
|---|---|---|
| Sheet thickness | 4.5 to 9 mm cladding; 15 to 24 mm compressed | Thicker grades for flooring and impact areas |
| Density | 1,250 to 1,500 kg/m³ standard | 1,700 kg/m³ and above for compressed sheet |
| Weight | 9 to 30 kg/m² | Thickness and density dependent |
| Sheet sizes | Commonly 2,400 to 3,600 mm by 900 to 1,200 mm | Planks to 4,200 mm |
| Modulus of rupture | Typically 10 to 22 MPa | Classified by category under AS/NZS 2908.2 |
| Moisture movement | About 0.1% between wet and dry | Sheet layout must allow for it at joints |
| Crystalline silica content | Present as ground quartz | Cutting releases respirable crystalline silica |
| Fire | Many products hold an AS 1530.1 Not Deemed Combustible result | Confirm the report for the product and thickness |
| Form | Flat or gently curved only | Not a moulded or three-dimensional material |
Composition and manufacture
Modern fibre cement is made by the Hatschek process. A dilute slurry of cement, ground silica, cellulose fibre and additives is picked up on a rotating sieve cylinder, transferred as a thin film to a felt, and wound onto a forming roll until the required thickness is reached. The green sheet is then pressed and cured, and autoclaved at around 180 °C under pressure so that the silica reacts with the cement to form calcium silicate hydrates. Autoclaving is what makes the sheet dimensionally stable and resistant to moisture cycling.
The cellulose fibre, usually refined softwood pulp, provides green strength and toughness. Until the mid 1980s the reinforcing fibre in Australian fibre cement was asbestos; sheet manufactured since then does not contain it, but material found on buildings from before that period must be treated as potentially asbestos containing until identified.
Formats and where it is used
- Flat sheet for rainscreen and direct fix cladding, express jointed, lapped or with a jointing system
- Weatherboard and plank profiles for residential cladding
- Compressed sheet for balcony and walkway floors, and for heavy duty facades
- Lining boards for wet areas, eaves and soffits
- Textured and pre-finished panels with factory applied coatings
Its strengths are consistency, cost, availability, low weight relative to masonry, and a straightforward fixing method. Its limit is form: fibre cement is a flat sheet product and can be curved only gently around a radius the sheet will accept without cracking. A curved, folded or deeply modelled elevation is the territory of moulded materials such as glass fibre reinforced concrete or fibre reinforced polymer.
Performance and detailing
Fibre cement moves with moisture content, roughly 0.1 percent between saturated and dry, which is enough to matter across a 3 metre sheet. Control joints, correct fastener spacing and edge distances, and the manufacturer’s specified gaps at sheet ends are not optional refinements. Fixing too close to an edge is the most common cause of corner cracking.
Sheets are generally installed over a drained and ventilated cavity with a compliant weather barrier behind, in the same way as any rainscreen. Cut edges are sealed and painted; unsealed edges wick water and cause paint failure and edge swelling. Most products are supplied primed rather than finished and require a site or factory applied coating system, which then carries the maintenance cycle.
Fire
Fibre cement is a cementitious material with no polymer matrix in the sheet itself, and many products hold an AS 1530.1 result of Not Deemed Combustible, which satisfies the non-combustibility requirement for external walls under the Deemed to Satisfy provisions of NCC 2022 Volume One (check the edition adopted in your jurisdiction). That result belongs to the tested product and thickness, so it has to be evidenced from the manufacturer’s report rather than assumed from the material class.
Cutting and silica dust
Fibre cement contains ground crystalline silica, and cutting, drilling, grinding or routing it releases respirable crystalline silica. It is not caught by Australia’s engineered stone prohibition, which excludes cement products, but it sits squarely inside the crystalline silica substance duties that have applied since 1 September 2024.
The controls are the ordinary hierarchy: score and snap in preference to power cutting, dust reducing blades with on-tool extraction where power cutting is unavoidable, cutting outdoors with the operator upwind, exclusion of others from the area, and respiratory protection selected for the task. The workplace exposure standard is 0.05 mg per cubic metre over eight hours. The silica free composites entry sets out the wider regulatory position.
Standards and references
- AS/NZS 2908.2 Cellulose cement products, Part 2: Flat sheets
- ISO 8336 Fibre cement flat sheets: product specification and test methods
- ASTM C1186 Standard Specification for Flat Fiber Cement Sheets
- AS 1530.1 combustibility; NCC 2022 Volume One Specification 7
- AS 3959 Construction of buildings in bushfire-prone areas, where BAL ratings apply
- Model Work Health and Safety Regulations, crystalline silica substance duties from 1 September 2024
Related terms
Questions specifiers ask
Is fibre cement non-combustible?
Many fibre cement products hold an AS 1530.1 result of Not Deemed Combustible, but the result belongs to the specific product and thickness. Ask for the test report, and remember that coatings, insulation backing and the rest of the external wall are assessed as part of the assembly.
Does fibre cement contain asbestos?
Not if it was manufactured in Australia after the mid 1980s, when cellulose fibre replaced asbestos. Sheet in buildings from before that period should be presumed to contain asbestos until it has been identified by testing.
Can fibre cement be curved?
Only gently. Thin sheets can be sprung around a large radius within the manufacturer’s limits. Tight curves, folds and three-dimensional relief require a moulded material such as GRC or FRP.
How should fibre cement be cut?
Score and snap wherever possible. Where power cutting is unavoidable, use a dust reducing blade with on-tool dust extraction, work outdoors and upwind, exclude other workers, and wear fitted respiratory protection. The dust contains respirable crystalline silica.
How long does fibre cement cladding last?
The substrate is durable for decades when detailed and drained correctly. The coating system is what drives maintenance, typically repainting every 10 to 15 years depending on exposure, colour and product.
Need a cementitious facade with geometry a flat sheet cannot deliver? ShapeShell-RC is a moulded GRC system, Not Deemed Combustible under AS/NZS 1530.1 as tested by Ignis Labs. See ShapeShell-RC specifications
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies. Last updated September 2026.