Join the waitlist
Join the waitlist

FREE WASTE GUIDE FOR DRYLINING CONTRACTORS

Plasterboard thickness and sizes

Standard plasterboard in the UK is 12.5mm thick and 2400 x 1200mm. The other common thicknesses are 9.5mm and 15mm, with 19mm boards for specialist systems. Insulated plasterboard is thicker again, from 22mm up to 93mm in British Gypsum's range.

Below are the thicknesses, the sheet sizes each one comes in, and what to check for ceilings and insulated board. Figures are from British Gypsum's product data sheets. Other manufacturers' ranges are similar but not identical, so check with your supplier.

Plasterboard thicknesses

  • 9.5mm: the thinnest standard board, available in fewer sizes.

  • 12.5mm: the standard thickness for walls and ceilings, and the widest choice of sizes.

  • 15mm: heavier board, also made in fire-rated and sound-rated versions for systems that need more performance.

  • 19mm: specialist boards such as Gyproc Plank, used in systems with high sound insulation, and Gyproc CoreBoard, used in shaftwall systems.

Fire-rated and acoustic boards, such as Gyproc FireLine and Gyproc SoundBloc, come in 12.5mm and 15mm. The thickness on its own doesn't set the fire or sound rating. The whole system does: board type, layers, studs and insulation together.

Plasterboard sheet sizes

  • 12.5mm wallboard:

    1200mm wide: 2400, 2700, 3000 and 3600mm long

    900mm wide: 1800mm long

  • 15mm wallboard:

    1200mm wide: 2400, 2700 and 3000mm long

    900mm wide: 1800mm long

  • 9.5mm wallboard: 900 x 1800mm and 1200 x 2400mm

Manufacturers list some other lengths, but they’re rarely held in stock, so check with your supplier before you plan around them. Fire-rated and sound-rated boards usually come in fewer lengths than standard wallboard.

Matching the sheet length to the wall height saves cutting and avoids horizontal joints. To work out how many sheets you need, see how many sheets of plasterboard do I need.

These are the sizes most suppliers keep in stock:

Ceiling plasterboard thickness

12.5mm is the usual board for plasterboard ceilings. Fire-rated or acoustic ceilings may call for 15mm board, specialist board or two layers.

The thickness you can use depends on the spacing of the joists or ceiling framing. Every manufacturer publishes maximum support centres for each board, so check them before you choose a thinner board.

For suspended plasterboard ceilings on a metal grid, see our MF ceiling guide.

Insulated plasterboard thickness

Insulated plasterboard is plasterboard bonded to a layer of insulation. Manufacturers quote the thickness in different ways. Some give the total thickness, and some give the insulation and the board separately, for example 25mm insulation + 12.5mm board. Check which one you’re looking at before you order.

British Gypsum quotes the total thickness. Its Gyproc ThermaLine range, all in 1200 x 2400mm sheets:

ThermaLine Basic (expanded polystyrene): 22, 30 and 40mm

ThermaLine Plus (extruded polystyrene): 27, 35, 40 and 48mm

ThermaLine PIR (PIR foam): 38, 53, 63, 78 and 93mm

The thickness you need depends on the U-value the wall has to reach, so it's set by the specification or the energy calculation for the job.

Get the free Drylining Waste Guide

Once you know the board, the next step is the order. Our free Drylining Waste Guide gives waste allowances for plasterboard, metal stud, track, insulation, screws and fixings, jointing compound and tape, plus five rules for ordering.

Common questions

What is the standard thickness of plasterboard?

12.5mm. It's the most common thickness for walls and ceilings in the UK and comes in the widest range of sizes.

What size is a standard sheet of plasterboard?

2400 x 1200mm, which covers 2.88m². 12.5mm board is also commonly stocked in 2700, 3000 and 3600mm lengths, and as a smaller 1800 x 900mm sheet.

Is 15mm plasterboard better than 12.5mm?

It's heavier and denser, and 15mm fire-rated and sound-rated boards are used in systems that need more performance. It isn't automatically the right choice. Use the board the specification or system calls for.

Does insulated plasterboard thickness include the board?

It depends on the manufacturer. British Gypsum's ThermaLine thicknesses are the total, board and insulation together. Other manufacturers list the insulation and board thickness separately. Check the product data sheet before you order.

We're building QFitout, drylining quoting software that applies these allowances for you when you price a job.

Join the waitlist to hear first when early access opens.

Join the waitlist

Sources