Curved Wall Calculator — Board Type, Radius & Stud Spacing

The tightest curve is achieved with 6mm flexible board (Glasroc F MultiBoard), which dry-bends to a minimum 600mm radius — two layers of 6mm also hold 600mm. Per the British Gypsum White Book GypWall CURVE table (dry bend, horizontal orientation): 9.5mm Gyproc WallBoard bends to a 1800mm minimum radius, 12.5mm to 3600mm, and 15mm to 4800mm. Always check the current figure for the exact board you are using, as values differ between manufacturers (e.g. Knauf quotes tighter radii).

Studs must be closer together on curved walls than straight walls. For 6mm flex board, studs should be at 150mm maximum centres. For wet-bent 12.5mm board, use 200mm centres. For dry-bent boards, 300mm centres is typical. The tighter the curve, the closer the studs need to be. All studs must be accurately positioned on the curve — use a trammel or template.

Wet bending is a traditional technique that lets a standard board follow a tighter radius than its dry-bend limit, but there is no single published British Gypsum or Knauf wet-bend radius — treat any quoted figure (around 2000mm for 12.5mm) as approximate and confirm with your board manufacturer. Modern British Gypsum GypWall CURVE instead uses dry-bend Glasroc F MultiBoard and does not require pre-wetting. If you do wet-bend: score the back paper at 50–75mm intervals perpendicular to the bend, dampen the scored side with a roller or sponge, leave roughly an hour until the core softens, then bend around the studs and screw in place. Allow to dry fully (12–24 hours) before taping and jointing. Dampen one side only — keep the other dry.

Yes, and it is often recommended. The British Gypsum White Book lists two layers of 6mm Glasroc F MultiBoard (total 12mm) at the same 600mm minimum radius as a single 6mm layer, so you keep the tight curve while gaining impact resistance and stiffness. Glasroc F is a Class A1 non-combustible board, but the fire rating of a curved wall comes from the complete tested system (board layers, fixings, framing and any cavity), not the board alone — specify a British Gypsum fire-rated GypWall CURVE build-up for a given rating rather than assuming a layer count gives it. Stagger the joints between layers by at least 600mm. Fix the first layer with 25mm screws and the second with 38mm screws.

The top and bottom tracks (head and sole plates) are formed by snipping the flanges of standard metal track at 50-75mm intervals and bending to the required curve. Alternatively, use pre-formed curved track or site-bend timber sole plates by kerfing (making saw cuts at close intervals). Fix the track securely to the floor and ceiling before inserting studs.