What is plasterboard?

Plasterboard (also called drywall, gypsum board, or by brand names such as Gyproc or Knauf) is a flat sheet made from a gypsum plaster core faced on both sides with paper liner. It is used to line the internal walls and ceilings of buildings, fixed to timber or metal stud framing or directly bonded to masonry walls using dot-and-dab adhesive. The surface can be finished with a thin skim coat of finishing plaster, or jointed and filled to a smooth surface for direct decoration.

What are the different types of plasterboard?

Standard plasterboard (white/ivory paper face, grey paper back) is used for most wall and ceiling applications. Fire-rated board (pink-coloured core containing glass fibres) provides improved fire resistance - used where Part B requires fire-rated partitions. Moisture-resistant board (green paper face) is specified in bathrooms and kitchens. Acoustic board (higher density, sometimes two layers) improves sound insulation between rooms. Insulated plasterboard (PIR or EPS foam bonded to the back) is used for internal wall insulation on solid walls.

What thickness of plasterboard should I use?

Standard wall lining uses 12.5mm board. Ceilings with joists at 400mm centres use 12.5mm; at 600mm centres, 15mm is recommended to avoid sag. Fire-rated partitions typically use 15mm or two layers of 12.5mm board to achieve the required fire resistance period. For dot-and-dab (adhesive bonded) wall lining on masonry, 12.5mm is standard. Two layers of 15mm fire board, each layer screwed separately, is a common solution for 60-minute fire-rated partitions.

What is skim coat plaster?

Skim coat plaster is a thin (2-3mm) finishing coat of gypsum plaster applied to the face of plasterboard to provide a smooth, fine surface ready for decoration. It is typically mixed to a thick cream consistency and applied in two thin passes - the first to fill the board surface and any joint tape, the second to flatten and smooth before the first is fully set. Skim should be feathered to a near-perfect flatness as any imperfections will show through emulsion paint, especially in raking light.

Finishes noun

Plasterboard

/ ˈplɑːstəbɔːd /

Also known as: drywall, gypsum board, wallboard, Gyproc, Knauf

Definition

Plasterboard is a flat building board made from a gypsum plaster core faced on both sides with paper liner. It is the standard internal lining for walls and ceilings in modern UK construction, fixed to timber or metal stud framing or bonded directly to masonry walls with dot-and-dab adhesive. It may be finished with a 2-3mm skim coat of gypsum finishing plaster for a smooth painted surface, or jointed and filled for a direct decoration finish.

In practice

Standard plasterboard comes in 1200 x 2400mm sheets (though 2700mm and 3000mm lengths are available for tall rooms) in 9.5mm, 12.5mm, and 15mm thicknesses. 12.5mm is the standard thickness for wall linings; 15mm is used for ceilings at wider joist spacings and for fire-rated constructions. Boards are fixed with drywall screws to timber or metal studwork at 150-200mm centres to framing members.

Specialist board types include: fire-resistant board (pink, with glass fibre core - used where 30 or 60-minute fire resistance is required under Part B); moisture-resistant board (green, for bathrooms and kitchen areas); acoustic board (heavier, for improved sound insulation); and insulated plasterboard (PIR or EPS laminate for internal wall insulation). All joints must be taped with joint tape and filled before skimming to prevent cracking at board edges.

Building Regulations

Relevant PartsPart B (fire), Part E (sound), Part L (energy)

Standard board (12.5mm)30 min fire resistance with one layer

Fire-rated partitionTwo layers 15mm fire board = 60 min fire resistance

PIR laminate boardMust be covered by plasterboard - cannot be left exposed

Approved Document B requires fire resistance for walls between dwellings and between garages and habitable rooms - typically achieved with fire-rated plasterboard. Approved Document E sets sound insulation targets between dwellings - achieved using acoustic plasterboard or double-layer standard board with staggered joints. Approved Document L requires PIR laminate plasterboard to be covered - it must not be left exposed in habitable spaces as it is combustible and falls below Euroclass C for reaction to fire when exposed.

Full Building Regulations guidance

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Plasterboard

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