Plasterboard types and thicknesses

Learn to identify plasterboard types, thicknesses and edge profiles so you always buy and fit the right board.

PT-01Understand what plasterboard is and the common thicknessesPlasterboard is a rigid sheet of gypsum (a soft mineral) sandwiched between two layers of paper. It's used to line stud walls and ceilings. The two thicknesses you'll meet most often are 9.5mm, which is thin and mainly used on ceilings, and 12.5mm, which is thicker and the standard choice for walls. A common beginner mistake is grabbing 9.5mm for a wall - it feels flimsy, dents easily, and doesn't take fixings well.

PT-02Learn the colour-coded board typesStandard board is usually grey or ivory paper, moisture-resistant board (for bathrooms and kitchens) is usually green, fire-resistant board is often pink, and acoustic board (extra soundproofing) is usually blue. Treat the colour as a quick visual clue, not proof - always check the printed text on the paper face too, because colours can vary slightly between manufacturers.

PT-03Feel the difference between tapered and square edgesRun your finger along the long edge of a sheet. A tapered edge has a shallow recess, so when two sheets meet, filler and jointing tape sit flush with the surface once dry. A square edge has no recess and is meant for walls that will be fully skimmed with a layer of plaster afterwards. Using the wrong edge type leaves a visible ridge or hollow along every joint.

PT-04Measure an exposed edge to find the thickness on an existing wallIf you need to know what's already on a wall, find a spot where the board edge is visible without any extra work - a loft hatch, a window reveal, or a gap where a radiator or fitting has been removed. Hold a tape measure against the exposed edge and read the thickness directly. Don't guess by tapping or by how the wall feels - thickness by eye is unreliable, even for people who've done this for years.

PT-05Confirm the type by checking the printed label, not just the colourManufacturers print the board type, thickness, and any fire or moisture rating along the paper face at intervals - look for this text on an offcut or an accessible edge. This is your proof you've identified it correctly, because colour alone can vary between brands and fade over time. If you can't find any printed text and you're not sure, treat the board as standard and unrated rather than assuming it's something better.

PT-06Match the board type to where it's goingUse moisture-resistant (green) board in bathrooms, kitchens, and utility rooms where damp is a risk, and standard board everywhere else for normal walls and ceilings. Fire-resistant (pink) board is required in specific locations, such as the wall separating an integral garage from the house, under Building Regulations Part B (fire safety) - if you're working on anything like this, check with your local Building Control before starting, since the rules depend on the exact layout of your house.

RULES

KNOW THE RULES

Fire separation between an integral garage and the house is covered by Building Regulations Part B. Confirm requirements with local Building Control before fitting board in this location.

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