Fibre Cement vs Plasterboard: Where Each Belongs on a Queensland Build

Plasterboard lines dry internal walls and ceilings. Fibre cement goes where water, weather or hard knocks would defeat a gypsum core: external cladding, eaves and soffits, floors and walls that will be tiled, and commercial wet areas. Most South East Queensland houses use both, and the order has to name the sheet and thickness for each zone.

The two sheets look similar on a pallet and cut with a similar score-and-snap action, which is why they get confused at order time. They are different materials doing different jobs. Plasterboard is a gypsum core wrapped in paper liner. Fibre cement is cement, sand and cellulose fibre pressed into a dense, rigid sheet. Put each one where it belongs and the wall lasts. Swap them and you get either a soft lining in a wet spot or a heavy, brittle sheet somewhere it was never needed.

What is the difference between fibre cement and plasterboard?

Plasterboard is a set gypsum core between two paper liners. The core gives it fire performance and a smooth, stable surface, the paper gives it a face that takes jointing compound and paint. It is light, fast to hang and fast to finish, and it is the lining behind almost every painted internal wall in Queensland. Its weakness is water. Once the paper liner and the core stay wet, the sheet loses strength and does not recover.

Fibre cement is a blend of Portland cement, ground sand and cellulose fibre, formed into sheets and cured under pressure. There is no paper and nothing in it that softens when wet. It is denser and heavier than plasterboard, harder to cut, and it will crack if a corner is dropped on concrete, but it holds tiles, shrugs off rain and is generally accepted as non-combustible. It is the sheet for anything outside the building envelope and for the wet or hard-wearing zones inside it.

For a full run-down of the grades of plasterboard stocked for internal work, from standard through moisture resistant, fire rated, acoustic and impact resistant, our types guide covers each one and where the NCC calls for it.

Where does plasterboard belong?

Every dry internal wall and ceiling. Bedrooms, living areas, hallways, offices, retail floors and the ceilings above them are plasterboard by default, in 10mm for ceilings and light partitions and 13mm for walls and ceilings at wider batten spacing. Where a wall has to do more than stand there, the grade changes rather than the material: fire rated board in a tested system for separating walls, acoustic board for party walls, impact resistant board in corridors and classrooms.

Wet areas are where the two overlap. Moisture resistant plasterboard is the accepted wall lining in bathrooms, laundries and kitchen splashback zones under NCC 2022, provided the waterproofing system covers it. Our guide to wet area and moisture resistant plasterboard sets out where it is required room by room.

Where does fibre cement belong?

Four places, and they account for almost every fibre cement sheet that leaves our yards.

• External cladding. Weatherboards, panels and sheet cladding in the James Hardie ranges such as Linea weatherboard, Axon and Stria panels, EasyLap panel and Hardie Flex sheet for board-and-batten work. These are the rain screen of the house and nothing paper-faced can do the job.
• Eaves and soffits. Thin flat sheet, typically 4.5mm or 6mm Hardie Flex, lines the underside of eaves, verandah ceilings and carport soffits where it sees wind-driven rain and humidity every summer.
• Wet area walls to be tiled. Villaboard lining is the standard fibre cement wall sheet behind tiles in showers, commercial bathrooms and anywhere a heavy tile load or a fully tiled wall is specified.
• Floors under tiles. Hardie ceramic tile underlay over timber or sheet flooring, and compressed fibre cement sheet such as Hardie Panel for wet area floors, balconies and decks that will be tiled.

Fibre cement also turns up on internal walls in garages, plant rooms and workshops, where a wall gets bumped and hosed and a painted plasterboard finish would not last a year.

Can moisture resistant plasterboard replace fibre cement in a bathroom?

Often, yes, and often it is the better choice. Under the wet area standard, both moisture resistant plasterboard and fibre cement are accepted water resistant substrates once the waterproofing membrane system is applied over them. For a domestic bathroom with a tiled shower and painted walls elsewhere, moisture resistant plasterboard on all walls with the membrane taken to the required heights is the common and compliant approach, and it finishes faster because the painted walls joint like any other plasterboard.

Specifiers reach for fibre cement where the wall is fully tiled floor to ceiling, where the tiles are large-format stone or heavy porcelain, in commercial and healthcare bathrooms that get washed down, and wherever the waterproofing detail calls for it. The deciding factors are the membrane system, the tile weight and the exposure, not a rule that one sheet is always right. If the waterproofer or the tiler has a preference, the order should follow it.

How do the two sheets compare?

What changes at order time?

The mistakes happen when one line on the order says "sheets" and the branch has to guess. A clean order for a house with both materials names the zone, the sheet and the thickness for each, and it carries the accessories that each sheet needs.

Fibre cement is also heavier and more brittle at the corners than plasterboard, so it travels on its own pallet and it needs to be stacked flat and clear of the ground on site. If the delivery has to be carried through a house to a rear bathroom, tell the branch so the sheets come in a size the carry path allows.

Getting both sheets supplied in South East Queensland

Bayside stocks James Hardie fibre cement alongside the full plasterboard range, so one order and one delivery covers the internal linings, the eaves, the wet area sheets and the fixings for each. Cladding profiles and compressed sheet are ordered to the job, while the everyday lines such as 6mm flat sheet and wet area lining are held across our Morningside, Redlands, Gold Coast and Caboolture yards.

Send through the room list with the zones marked and we will work back to a sheet schedule for both materials. Call the trade counter on (07) 3245 4488 or send the plans through and we will price it the same day.